This past week was definitely the busiest of the year around here. For the first time in a long time, I had a tracker (3rd set of eyes, either does all the talking or does all the typing) on one session, and then became the tracker the next session. Its all very exhilarating for the most part. The atmosphere changes, the little side conversations end, and the tension gets a tad thicker. Everyone starts concentrating a little more.
This first busy session wasn't THAT bad, really. Utica was combined with Watertown sector, as normal. Each sector has its own frequency, so we continually listen to, and transmit on, both. This causes aircraft to talk over each other sometimes, but we learn to deal with it. Utica's main frequency site was down for maintenance so we were using the backup, which conveniently became unusable right as a bunch of westbound overflights started checking in. I couldn't hear anyone, so we got everyone on that frequency to switch to Watertown's, and then spread the word to all the surrounding sectors to use the one good frequency only. For whatever reason, all the IAD landers were coming over SYR, and I had 30 miles in trail. Nothing a few vectors wouldn't fix. I turned a few CLE arrivals for spacing as well, and then said goodbye to everyone. The third issue were the rides. No one liked FL320, 340 or 360. So, while I would have gotten all the IADs down to FL300, the DCA would have stayed at FL280, and everyone else would have just gone over the top, instead, everyone wanted FL280 and FL300. That obviously wouldn't work, and it was hard to tell where the IAD vectors would take them in relation to the westbound overflights, so a lot of guys just had to stay at FL240 and FL260, in the interest of air safety. The rides were smooth, so they didn't complain much.
The second part of our fun afternoon came at Delancy(DNY)/Hancock(HNK) sector combined up. The frequencies worked, so that was good. We needed them. I had never been the actual tracker before. I had always been there as the radar controller already and done all the talking, standing behind the tracker sitting at the keyboard. This time, I got to sit and type. This is fine by me, I can hold my own on the keyboard. I have heard other controllers recall that back when we used strips all the time, they knew when they couldn't take it anymore if they didn't have time to write on the strips as they talked. I have come to realize the new generation will find our limit when we can't type fast enough to keep up with our own words and thoughts. As the tracker, I quickly realized that it was MY job to take hand offs, something I hadn't really pondered before. I figured my radar controller would yell at me when they couldn't take it anymore. This presents a problem in relation to how we're trained to take hand offs. As a controller, anytime you take a hand off from another sector, we know what we have to do with that airplane. Then we have to figure out HOW we're going to accomplish it. Either: 1- we don't have to do anything. 2- it'll be no problem or 3- how on earth are we gonna make this happen. Should I just start talking hand offs with wild abandon!?
As I sat there, the three of us all collectively contemplated how ugly this could get. Delancy's issue is that all the planes have to descend at either other or parallel to each other, and we often require high rates of decent to make it all happen. Its very disconcerting when you have to start descending a plane from FL260 to FL220, but the plane that is going UNDER that plane is still out of FL330. But if you don't start the first one down now, they'll never get to FL190 once the second one is level at FL180.
So, the situation is this: Get the SWF lander down to 17000 now and then he can cross DNY at 11000 at his leisure. Then get the EWR lander down to FL180 but not before the AVP guy gets down to 16000, over the SWF lander. The HPN arrivals also need to step down over the EWR and AVP down to FL180. They all need to get under a PIT going against the flow west over HNK at FL260. Then the PHL needs to somehow cross them all on the way from FL260 to FL190. That's the MAIN issue, as we also have ALB arrivals not really getting in anyones way, and a LGA arrival that we'll just leave above the PHL. There are a few other props slowly moving at 15000 just to keep the scope adequately cluttered. The radar controller does a fine job, and 20 minutes later, I'm off to relieve the RKA radar controller. Its a nice little warm up to what promises to be a long summer of brutal traffic.
DM
March 23, 2008
Down In A Hole
Happiness is:
Sitting in the back corner of the area, one-holing Albany sector after all the Newark overseas arrivals are gone. The area is dim to begin with, but where ALB is situated back there seems to encourage the eyes to continue its scan elsewhere. Don't mind me, I'm just quietly letting the rest of my day finish off back here, alone.
Some would call me crazy, some would agree with me, and are willing to pass breaks to preserve solitude.
I THOUGHT I was all set. Saturday afternoon, steady traffic but nothing crazy. Nothing going on that makes the supervisor take notice enough to give me a D-side (one-holing means its slow enough to not require the second person, the Data-side controller, leaving the radar controller to handle the radios AND the flight data aspects of the sector). The Albany departures are climbing well above the BDL arrival flow, I give a BDL departure a shortcut to SYR to avoid the MHT arrival crossing eastbound, I turned a PVD arrival direct BDL to avoid the BDL departure, and a biz-jet heading to Teterboro is safely pushed under all of them. Life is good. But wait...
Here comes the supervisor, its "skill-check" time. Four pm, and there is the usual rush of east bounds coming into the Rockdale (RKA) sector. One of the night-shifters shows up to relieve me so I can move over to RKA to show I have "skills" with actual airplanes. That last scenario at ALB was all done and I had nothing but a blank scope to show for it. He happily sits down to a traffic-less sector. I plug in along side a supervisor, pen and paper waiting to fully document any and all discrepancies. I am a recent graduate of the training program, so expectations are high. While RKA is busier this time of day than ALB, it is much less complex. I few descents, a few shortcuts, one turn for spacing, speed assigned to keep it, and 30 minutes later, I live to see another day. I sign my name on the dotted line indicating my receipt of the critique, and its off to the break room for a little ping pong.
Happiness is getting paid to do this.
DM
Sitting in the back corner of the area, one-holing Albany sector after all the Newark overseas arrivals are gone. The area is dim to begin with, but where ALB is situated back there seems to encourage the eyes to continue its scan elsewhere. Don't mind me, I'm just quietly letting the rest of my day finish off back here, alone.
Some would call me crazy, some would agree with me, and are willing to pass breaks to preserve solitude.
I THOUGHT I was all set. Saturday afternoon, steady traffic but nothing crazy. Nothing going on that makes the supervisor take notice enough to give me a D-side (one-holing means its slow enough to not require the second person, the Data-side controller, leaving the radar controller to handle the radios AND the flight data aspects of the sector). The Albany departures are climbing well above the BDL arrival flow, I give a BDL departure a shortcut to SYR to avoid the MHT arrival crossing eastbound, I turned a PVD arrival direct BDL to avoid the BDL departure, and a biz-jet heading to Teterboro is safely pushed under all of them. Life is good. But wait...
Here comes the supervisor, its "skill-check" time. Four pm, and there is the usual rush of east bounds coming into the Rockdale (RKA) sector. One of the night-shifters shows up to relieve me so I can move over to RKA to show I have "skills" with actual airplanes. That last scenario at ALB was all done and I had nothing but a blank scope to show for it. He happily sits down to a traffic-less sector. I plug in along side a supervisor, pen and paper waiting to fully document any and all discrepancies. I am a recent graduate of the training program, so expectations are high. While RKA is busier this time of day than ALB, it is much less complex. I few descents, a few shortcuts, one turn for spacing, speed assigned to keep it, and 30 minutes later, I live to see another day. I sign my name on the dotted line indicating my receipt of the critique, and its off to the break room for a little ping pong.
Happiness is getting paid to do this.
DM
March 13, 2008
Delays, get over it.
I promised this blog was going to start deviating drastically, so I'll keep this one short. Its just a thought.
Everyone always rants and raves about how horrible the delays are. Or they're on TV, claiming to have invented a wheel of a different shape, which apparently will rid the world of pesky delays. Instead of taking more time to set the record straight, ponder this: If we were able to mystically eliminate delays in the aviation industry....I'm pretty sure we'd be the ONLY form of transportation that wouldn't have any delays.
Next time you're patiently waiting your turn at a traffic light watching the cars cross in front of you, or you're the pedestrian also waiting for the light to change, so you can sit on the bench to wait for the bus to arrive, or next time it snows and the train runs late, or there is a gale force wind making a quick trip across the bay less than desirable at that moment, just slough it off. Get over it. For some reason, we think that aviation, and the airlines in particular, can somehow be void of common nature. To run late. If anything, the reason its such a big deal in aviation is because the airlines aren't always forthcoming as to why. Since "ATC delays" are the main "cause" of delays, we seem to think we can simply do something, anything to the ATC and make the delay go away. Bzzzzzzzzz.
DM
Everyone always rants and raves about how horrible the delays are. Or they're on TV, claiming to have invented a wheel of a different shape, which apparently will rid the world of pesky delays. Instead of taking more time to set the record straight, ponder this: If we were able to mystically eliminate delays in the aviation industry....I'm pretty sure we'd be the ONLY form of transportation that wouldn't have any delays.
Next time you're patiently waiting your turn at a traffic light watching the cars cross in front of you, or you're the pedestrian also waiting for the light to change, so you can sit on the bench to wait for the bus to arrive, or next time it snows and the train runs late, or there is a gale force wind making a quick trip across the bay less than desirable at that moment, just slough it off. Get over it. For some reason, we think that aviation, and the airlines in particular, can somehow be void of common nature. To run late. If anything, the reason its such a big deal in aviation is because the airlines aren't always forthcoming as to why. Since "ATC delays" are the main "cause" of delays, we seem to think we can simply do something, anything to the ATC and make the delay go away. Bzzzzzzzzz.
DM
March 12, 2008
More Confusion?
I have decided to turn this blog in a different direction.
While past blog posts have focused on a more technical aspect of ATC, the future of this lowly blog will be centered around a more informal, day-to-day narrative. The most recent post, "The Mid Flick", is an example how I hope to change the writing style. Don't expect too much, because I am never afraid to let things get a little out of hand!
The idea behind this change is simple: If I take specific snapshots of traffic situations during the upcoming summer traffic season, the journey though the land of ATC can be both more interesting and more informative for all of us.
DM
While past blog posts have focused on a more technical aspect of ATC, the future of this lowly blog will be centered around a more informal, day-to-day narrative. The most recent post, "The Mid Flick", is an example how I hope to change the writing style. Don't expect too much, because I am never afraid to let things get a little out of hand!
The idea behind this change is simple: If I take specific snapshots of traffic situations during the upcoming summer traffic season, the journey though the land of ATC can be both more interesting and more informative for all of us.
DM
March 9, 2008
The Mid flick
Now that I am fully checked out, done with training, on my own, left to my own devices, creating my own havoc over upstate NY, I am also working the occasional "mid" shift. I like the overnight mid shift for two reasons: First, I have weird sleeping habits, and they are willing to pay me to be awake in the middle of the night. The second reason is the traffic. There's hardly any. This is not really why I enjoy the mid, however. There is SOME traffic, but it's different. It is really quiet so everyone is direct somewhere they normally can't go direct to during the day. This creates new and still-interesting (to the new guy) conflictions.
It still amazes me, and irritates the pilots, when two planes are going to hit unless I take action....at 4:30 in the morning. So I take action, as I am trained to do. The pilots often question the turn off their direct routing, or a descent from their optimal cruise altitude. After all, they act like they're the only plane in they sky at 3 in the afternoon, imagine their dismay when they realize they're not the only ones flying at 3 in the morning!
So, there I was, working the mid, its 4:30am, and I have 3 airplanes. Cleveland Center is still on their back-up system (the main computer is reset for maintenance at night sometimes), so I only find out about my next airplanes when they call on the line for the hand off with flight plan information. 5am is often a "busy" time, as all the trans-con red-eye flights are approaching BOS and BDL and NY from the west. I am already talking to the first jetBlue Airbus at FL350 heading to Boston. There is another following about 30 miles back at the same altitude. I had just taken the clock off the wall above the headset boxes to skip an hour for daylight savings, so half the planes are running an hour later than normal. Its not nearly as "busy" as it could be. I get an Air Canada full of sleeping vacationers heading north to the crummy weather in Ottawa, also at FL350. The high sector in Montreal Centre also has a United flight from Kuwait to Dulles at FL400 direct Syracuse.
Normally, even at this late hour, New York still needs the IAD arrival descending to FL300, as they also have a large eastbound rush of red-eyes that are traffic for this crossing Triple Seven. I have three, potentially four planes that are crossing just south of Syracuse. Three of them are at FL350, and the fourth needs to somehow get from FL400 to FL300. So I start the Air Canada down to FL330, and the United down to FL340. The winds are strong out of the southwest, so I figure I'm only doing the United jet a favor by getting him out of the strongest headwinds. Apparently not. He firmly lets me know that by starting down now (an hour from his destination) he is wasting 2500 pounds of fuel. Just then, Cleveland calls with the second jetBlue, so I tell the United to just maintain FL380 for now, standby with your sad story, and I pick up the line to take the hand off. Cleveland takes a point out on the United with control for lower if I need it. This covers me all the way down to FL300 if NY can't take this guy at his current altitude. I call NY next and give them the United hand off, including approval for FL380, since most of her red-eyes are running late tonight. I spring the good news to the United and explain to him that we don't enjoy descending him through all of our traffic to meet that restriction, but we don't really have a choice most of the time.
Now that all my traffic is safe, I take the hand off on the third Boston, call Montreal to hand off the Air Canada, and then, as often happens at 5am, I am left with nothing to do. So, I thought about how much gas I just saved United Airlines. 2500 pounds. A gallon of Jet-A weighs about 7 pounds, and its costs about 7 dollars a gallon, so the math is easy. I saved United Airlines about 2500 bucks by making a phone call.
Granted, my first though was that since we're running the FAA like a business now I should be able to claim some of this profit as my own. UAL Corp should be mailing me a check for like 10 percent of their savings since we're technically business partners.
It also made me remember what a retired controller from my area once said. He always thought that the union has been going about this contract/non-tract strife the wrong way. We are not in the business of saving money for anyone, or making money. We are in the business of making sure airplanes and their passengers arrive safely at their destination. We go out of our way to get airplanes up to smooth, fuel efficient altitudes. We go out of our way to give airplanes shortcuts so they can save time and money. The FAA, the flying public, and the airlines take the safety aspect for granted. Airlines try to make flying more efficient and cost effective for themselves. Perhaps if they added up the combined cost benefits of every shortcut we issue every day, someone would realize that we're not the enemy in this game of money and power. We're here to help. The difference is that we don't put money first. We put safety first. Saving money is pretty pointless if you can't get to your destination to spend it.
DM
It still amazes me, and irritates the pilots, when two planes are going to hit unless I take action....at 4:30 in the morning. So I take action, as I am trained to do. The pilots often question the turn off their direct routing, or a descent from their optimal cruise altitude. After all, they act like they're the only plane in they sky at 3 in the afternoon, imagine their dismay when they realize they're not the only ones flying at 3 in the morning!
So, there I was, working the mid, its 4:30am, and I have 3 airplanes. Cleveland Center is still on their back-up system (the main computer is reset for maintenance at night sometimes), so I only find out about my next airplanes when they call on the line for the hand off with flight plan information. 5am is often a "busy" time, as all the trans-con red-eye flights are approaching BOS and BDL and NY from the west. I am already talking to the first jetBlue Airbus at FL350 heading to Boston. There is another following about 30 miles back at the same altitude. I had just taken the clock off the wall above the headset boxes to skip an hour for daylight savings, so half the planes are running an hour later than normal. Its not nearly as "busy" as it could be. I get an Air Canada full of sleeping vacationers heading north to the crummy weather in Ottawa, also at FL350. The high sector in Montreal Centre also has a United flight from Kuwait to Dulles at FL400 direct Syracuse.
Normally, even at this late hour, New York still needs the IAD arrival descending to FL300, as they also have a large eastbound rush of red-eyes that are traffic for this crossing Triple Seven. I have three, potentially four planes that are crossing just south of Syracuse. Three of them are at FL350, and the fourth needs to somehow get from FL400 to FL300. So I start the Air Canada down to FL330, and the United down to FL340. The winds are strong out of the southwest, so I figure I'm only doing the United jet a favor by getting him out of the strongest headwinds. Apparently not. He firmly lets me know that by starting down now (an hour from his destination) he is wasting 2500 pounds of fuel. Just then, Cleveland calls with the second jetBlue, so I tell the United to just maintain FL380 for now, standby with your sad story, and I pick up the line to take the hand off. Cleveland takes a point out on the United with control for lower if I need it. This covers me all the way down to FL300 if NY can't take this guy at his current altitude. I call NY next and give them the United hand off, including approval for FL380, since most of her red-eyes are running late tonight. I spring the good news to the United and explain to him that we don't enjoy descending him through all of our traffic to meet that restriction, but we don't really have a choice most of the time.
Now that all my traffic is safe, I take the hand off on the third Boston, call Montreal to hand off the Air Canada, and then, as often happens at 5am, I am left with nothing to do. So, I thought about how much gas I just saved United Airlines. 2500 pounds. A gallon of Jet-A weighs about 7 pounds, and its costs about 7 dollars a gallon, so the math is easy. I saved United Airlines about 2500 bucks by making a phone call.
Granted, my first though was that since we're running the FAA like a business now I should be able to claim some of this profit as my own. UAL Corp should be mailing me a check for like 10 percent of their savings since we're technically business partners.
It also made me remember what a retired controller from my area once said. He always thought that the union has been going about this contract/non-tract strife the wrong way. We are not in the business of saving money for anyone, or making money. We are in the business of making sure airplanes and their passengers arrive safely at their destination. We go out of our way to get airplanes up to smooth, fuel efficient altitudes. We go out of our way to give airplanes shortcuts so they can save time and money. The FAA, the flying public, and the airlines take the safety aspect for granted. Airlines try to make flying more efficient and cost effective for themselves. Perhaps if they added up the combined cost benefits of every shortcut we issue every day, someone would realize that we're not the enemy in this game of money and power. We're here to help. The difference is that we don't put money first. We put safety first. Saving money is pretty pointless if you can't get to your destination to spend it.
DM
June 29, 2007
Time out
Its summer time and I have been spending my moments of inspiration away from the computer. Radar training has been humbling and I have more important things to focus on other than writing this blog. I figure I'll get back to writing about the NAS in the future. Until then, don't miss me.
DM
DM
May 13, 2007
Delays at your Departure Airport Part 1
Lets get right to it, shall we. Be advised, this may get a little complicated.
If you kept exploring around that FAA website, perhaps you found another Traffic Management "product": the AADC or Airport Arrival Demand Chart. It's difficult to explain how to get the most out of this chart, as the data is constantly changing for each airport. The idea is to double click on your airport, and the chart will populate with data. The horizontal white line is the Arrival Rate, as discussed in the previous post. Occasionally, the columns of arrivals will peak above the white line, indicating that the arrival demand exceeds the acceptance rate of the airport for that hour. If you select the 15 button instead of 30 or 60 to the left of the airport selection box, the data will show columns of arrivals every 15 minutes. You'll notice how arrival demands increase dramatically in very short periods of time. Also, you'll notice how the spikes in demand occur more frequently in the 15 minute increments, as they would in the 60 minute graphic. As I write this, LGA shows 2 hours of demand higher than capacity in the 60 minute display, but when showing the 15 minute display, there are 12 periods that exceed capacity, or 3 hours worth. So, between 11am-2pm, there are 12 instances when flights will incur a guaranteed delay. Proof of this is something that really caught my attention when I first started training: The SAME flights often are victim of the same delay every day due to this lack of capacity. The same flights are delayed on the ground or asked to hold in the air on an almost daily basis.
So, these few flights are delayed daily, regardless of the weather, because the airport can NEVER handle as many flights as are scheduled. So, when the weather becomes less than ideal, even more flights must be delayed. With proper planning, these flights will be held on the ground. Lets discuss how the length of the delay is calculated.
In the last post, I mentioned how the weather affects the two main variables in relation to airport acceptance rate. The overall visibility and weather, which determines spacing on final approach, and the wind, which mainly determines the runway configuration, thus setting the actual acceptance rate. With these two values set for the period of time that the weather will require use of said approaches and runways, Traffic Management Unit (TMU to save bandwidth) then determines the Miles in Trail (MIT) requirement for each arrival fix. To explain, each approach control airspace has 2-4 arrival fixes (fixes are imaginary points in space that aircraft can determine using their on board computers, though sometimes they are simply well-placed ground based navigational aids). All traffic landing at the main airport are always routed along charted arrival routes which organizes traffic flow over these main arrival fixes. Depending on the number of arrival fixes a MIT requirement for each fix is determined. If traffic on final approach must be 5 miles apart due to cloudy weather, and there is only one runway in use for landing, and there are 4 arrival fixes, TMU would require 20 miles between aircraft arriving from the same fix. Aircraft are sequenced to these arrival fixes by the Center, and the approach control (TRACON) would then take the 4 streams of traffic from different directions (each with planes 20 miles in trail of each other) and line them up on final approach 5 miles apart. Centers are much more adept to using vectors and speed control to achieve the 20 MIT needed, as the sectors are much bigger. Also, the 20 MIT requirement is often achieved hundreds of miles from the arrival fix, if the sectors close to the arrival fix are too busy or not big enough to get the spacing needed. I'll discuss that later on.
As we move farther from the airport, the spacing requirement will often grow. While the traffic flow may be organized in 4 flows close to the destination, this organization can't exist forever. Aircraft approach the airport from every direction, on a fairly direct route from their departure airport. At a point a few hundred miles from the arrival airport, the routes become standardized and they join the Standard Terminal Arrival Route (STAR). Each STAR may contain transitions which aide the pilot in determining the best way file his/her flight plan to join the STAR. There will be one Center sector that will be in charge of determining the sequence of all arrivals to one of the STARs. Traffic on each transition, or a set of transitions, would be worked by a different sector. These outlaying sectors would have their own MIT requirement based on their percentage of the overall traffic flow to that arrival fix. So, assuming the main sequencing sector is required to achieve 20 miles between planes to feed into the approach control, and there were 2 transition routes into the main sector, both with equal amounts of inbound traffic, TMU would determine that each outlaying sector should provide the main sector with 40 miles in trail. The main sector would vector the two flows together into a single line 20 miles in trail. This is rather simplified, but is meant to show the theory behind miles in trail. Often times, its actually reverse simplified. Every sector in the center working arrivals to that airport would have to provide the next sector with 20 miles in trail. This would cause the delays to happen slowly over the course of the flight, but would require every sector along the way to vector planes and delay them slightly. Flights would be constantly adjusted for each sector to accomplish its MIT requirement, as opposed to the plane being turned and slowed once or twice. This is where the ground delay comes in to solve this problem.
TMU has established a program that determines the amount of delay required for each flight so that it can depart into a predetermined slot so that it will experience the smallest airborne delay possible. Lets take a step back first.
We have explored MIT requirements per arrival fix, but lets look at it from a system-wide perspective. While, we know we'll need 20 miles in trail over a certain fix, the idea is still to determine a sequence into the airport from all 4 fixes together. We don't really care which direction they're coming from, only when they are going to arrive. Also, we'll need to figure out when they're going to depart and how long it will take to get to where they are going. To do this, the TMU at the arrival airport will determine the MIT per arrival fix. The TMU at the departure airport will delay aircraft on the ground so that they depart at a time that will allow the Center a fighting chance at achieving that spacing with minimal vectors.
I discussed how the arrival flows coming into each airport is organized into 4 flows. The same is true with departures. In Boston Center, for example, we have 5 fixes that aircraft fly over when they depart the Center. There are more, in reality, but these 5 are the fixes that aircraft use when they are flying to airports that need miles in trail. So, TMU has determined the amount of time it takes for airliners to fly from each airport to each of those 5 fixes. Oh, by the way, these fixes are SYR, HNK, HTO, SAX, and SBJ. Look 'um up. With these flying times in hand, they separate all departures by their arrival airport. All aircraft flying to Atlanta would go together, all those flying to Ohare would go together, etc. If we need 20 miles in trail (airlines fly about 7-8 miles a minute) 3 minutes between planes is the goal of the program. Each control tower is advised that every aircraft destined to the airports specified as needing MIT would need special permission to depart. The tower would call TMU on the phone, advise them of when the plane wants to depart, and TMU calculates the best time for that plane to depart, based on the other departures from the other airports in the center. The solution, of course, isn't simply to space the departure times of each departure by 3 minutes. A departure from Bangor, ME (BGR) can departure well ahead of the Providence, RI (PVD) departure, but the Providence plane will still be in front. The key is not to allow the Providence departure to leave at a time that will tie up the Bangor departure time wise. There would be a 6 minute window when the PVD departure can't go. Add in BDL (Hartford), ALB (Albany), BTV (Burlington), MHT (Manchester), PWM (Portland), and BOS (Boston), and things get complicated. Meanwhile, the airlines schedule their flights to depart at slightly different times so that they ARE TIED as they leave the center. The schedule is designed to do that. In the Hub-and-Spoke system of the major airlines, the goal for the airline is for everyone to arrival simultaneously at the hub airport so that everyone can connect flights and then leave simultaneously. This of course works out well, until we have to space you on final. Darnnit!
To summarize:
As the final controller spaces planes on final approach, the gap between flights increases. This gap expands out in time over the whole country. Each plane gets moved back further and further to increase spacing. Eventually, planes are delayed to a point where the last plane in line hasn't even left yet. You can wait for your place in line at the gate, or you can get vectored all over the sky. I'll take the ground delay, thanks (both as a controller AND as a passenger).
Next up, I'll discuss the impact of en-route weather and how sector capacity is a limiting factor as well as runways.
DM
If you kept exploring around that FAA website, perhaps you found another Traffic Management "product": the AADC or Airport Arrival Demand Chart. It's difficult to explain how to get the most out of this chart, as the data is constantly changing for each airport. The idea is to double click on your airport, and the chart will populate with data. The horizontal white line is the Arrival Rate, as discussed in the previous post. Occasionally, the columns of arrivals will peak above the white line, indicating that the arrival demand exceeds the acceptance rate of the airport for that hour. If you select the 15 button instead of 30 or 60 to the left of the airport selection box, the data will show columns of arrivals every 15 minutes. You'll notice how arrival demands increase dramatically in very short periods of time. Also, you'll notice how the spikes in demand occur more frequently in the 15 minute increments, as they would in the 60 minute graphic. As I write this, LGA shows 2 hours of demand higher than capacity in the 60 minute display, but when showing the 15 minute display, there are 12 periods that exceed capacity, or 3 hours worth. So, between 11am-2pm, there are 12 instances when flights will incur a guaranteed delay. Proof of this is something that really caught my attention when I first started training: The SAME flights often are victim of the same delay every day due to this lack of capacity. The same flights are delayed on the ground or asked to hold in the air on an almost daily basis.
So, these few flights are delayed daily, regardless of the weather, because the airport can NEVER handle as many flights as are scheduled. So, when the weather becomes less than ideal, even more flights must be delayed. With proper planning, these flights will be held on the ground. Lets discuss how the length of the delay is calculated.
In the last post, I mentioned how the weather affects the two main variables in relation to airport acceptance rate. The overall visibility and weather, which determines spacing on final approach, and the wind, which mainly determines the runway configuration, thus setting the actual acceptance rate. With these two values set for the period of time that the weather will require use of said approaches and runways, Traffic Management Unit (TMU to save bandwidth) then determines the Miles in Trail (MIT) requirement for each arrival fix. To explain, each approach control airspace has 2-4 arrival fixes (fixes are imaginary points in space that aircraft can determine using their on board computers, though sometimes they are simply well-placed ground based navigational aids). All traffic landing at the main airport are always routed along charted arrival routes which organizes traffic flow over these main arrival fixes. Depending on the number of arrival fixes a MIT requirement for each fix is determined. If traffic on final approach must be 5 miles apart due to cloudy weather, and there is only one runway in use for landing, and there are 4 arrival fixes, TMU would require 20 miles between aircraft arriving from the same fix. Aircraft are sequenced to these arrival fixes by the Center, and the approach control (TRACON) would then take the 4 streams of traffic from different directions (each with planes 20 miles in trail of each other) and line them up on final approach 5 miles apart. Centers are much more adept to using vectors and speed control to achieve the 20 MIT needed, as the sectors are much bigger. Also, the 20 MIT requirement is often achieved hundreds of miles from the arrival fix, if the sectors close to the arrival fix are too busy or not big enough to get the spacing needed. I'll discuss that later on.
As we move farther from the airport, the spacing requirement will often grow. While the traffic flow may be organized in 4 flows close to the destination, this organization can't exist forever. Aircraft approach the airport from every direction, on a fairly direct route from their departure airport. At a point a few hundred miles from the arrival airport, the routes become standardized and they join the Standard Terminal Arrival Route (STAR). Each STAR may contain transitions which aide the pilot in determining the best way file his/her flight plan to join the STAR. There will be one Center sector that will be in charge of determining the sequence of all arrivals to one of the STARs. Traffic on each transition, or a set of transitions, would be worked by a different sector. These outlaying sectors would have their own MIT requirement based on their percentage of the overall traffic flow to that arrival fix. So, assuming the main sequencing sector is required to achieve 20 miles between planes to feed into the approach control, and there were 2 transition routes into the main sector, both with equal amounts of inbound traffic, TMU would determine that each outlaying sector should provide the main sector with 40 miles in trail. The main sector would vector the two flows together into a single line 20 miles in trail. This is rather simplified, but is meant to show the theory behind miles in trail. Often times, its actually reverse simplified. Every sector in the center working arrivals to that airport would have to provide the next sector with 20 miles in trail. This would cause the delays to happen slowly over the course of the flight, but would require every sector along the way to vector planes and delay them slightly. Flights would be constantly adjusted for each sector to accomplish its MIT requirement, as opposed to the plane being turned and slowed once or twice. This is where the ground delay comes in to solve this problem.
TMU has established a program that determines the amount of delay required for each flight so that it can depart into a predetermined slot so that it will experience the smallest airborne delay possible. Lets take a step back first.
We have explored MIT requirements per arrival fix, but lets look at it from a system-wide perspective. While, we know we'll need 20 miles in trail over a certain fix, the idea is still to determine a sequence into the airport from all 4 fixes together. We don't really care which direction they're coming from, only when they are going to arrive. Also, we'll need to figure out when they're going to depart and how long it will take to get to where they are going. To do this, the TMU at the arrival airport will determine the MIT per arrival fix. The TMU at the departure airport will delay aircraft on the ground so that they depart at a time that will allow the Center a fighting chance at achieving that spacing with minimal vectors.
I discussed how the arrival flows coming into each airport is organized into 4 flows. The same is true with departures. In Boston Center, for example, we have 5 fixes that aircraft fly over when they depart the Center. There are more, in reality, but these 5 are the fixes that aircraft use when they are flying to airports that need miles in trail. So, TMU has determined the amount of time it takes for airliners to fly from each airport to each of those 5 fixes. Oh, by the way, these fixes are SYR, HNK, HTO, SAX, and SBJ. Look 'um up. With these flying times in hand, they separate all departures by their arrival airport. All aircraft flying to Atlanta would go together, all those flying to Ohare would go together, etc. If we need 20 miles in trail (airlines fly about 7-8 miles a minute) 3 minutes between planes is the goal of the program. Each control tower is advised that every aircraft destined to the airports specified as needing MIT would need special permission to depart. The tower would call TMU on the phone, advise them of when the plane wants to depart, and TMU calculates the best time for that plane to depart, based on the other departures from the other airports in the center. The solution, of course, isn't simply to space the departure times of each departure by 3 minutes. A departure from Bangor, ME (BGR) can departure well ahead of the Providence, RI (PVD) departure, but the Providence plane will still be in front. The key is not to allow the Providence departure to leave at a time that will tie up the Bangor departure time wise. There would be a 6 minute window when the PVD departure can't go. Add in BDL (Hartford), ALB (Albany), BTV (Burlington), MHT (Manchester), PWM (Portland), and BOS (Boston), and things get complicated. Meanwhile, the airlines schedule their flights to depart at slightly different times so that they ARE TIED as they leave the center. The schedule is designed to do that. In the Hub-and-Spoke system of the major airlines, the goal for the airline is for everyone to arrival simultaneously at the hub airport so that everyone can connect flights and then leave simultaneously. This of course works out well, until we have to space you on final. Darnnit!
To summarize:
As the final controller spaces planes on final approach, the gap between flights increases. This gap expands out in time over the whole country. Each plane gets moved back further and further to increase spacing. Eventually, planes are delayed to a point where the last plane in line hasn't even left yet. You can wait for your place in line at the gate, or you can get vectored all over the sky. I'll take the ground delay, thanks (both as a controller AND as a passenger).
Next up, I'll discuss the impact of en-route weather and how sector capacity is a limiting factor as well as runways.
DM
April 28, 2007
Delays, an Introduction
This time of year seems perfect for discussing the biggest issue in air travel. Delays. There may be a few different reasons for delays, but, for the most part, they are all caused by the need to maintain safety.
While it may seem that most delays are due to poor weather, and this is mostly true, the root of most delays stem from a lack of runways at your destination. I will stress that this lack of runways at our busiest airports is made most apparent during periods of bad weather, but is not exclusively due to weather. Also, some delays are due to bad weather in the en-route phase of flight, and have nothing to do with the weather at your origin OR destination. These are the delays that most puzzle the general public, in my opinion.
Let us start with some basics. Traffic Management has determined all the possible arrival and departure runway configurations at every major airport in the country. The use of each configuration depends on the visibility, cloud bases, and most importantly, the prevailing wind. Some configurations are capable of more operations per hour than others. The actual number of arrivals and departures per hour are publicly documented for each configuration at each major airport. They can be found here. I'll use this link to support a few examples.
Simply click on the plus signs next to East or West Directory, and then pick an ARTCC (Center) and then choose and airport. A chart should appear showing the relationship between each runway configuration and the arrival and departure rates in both optimal visual conditions and when instrument approach must be used. You'll notice the rates are different for visuals as opposed to when ILS approaches are in use, due to the increased separation required on final approach. I'll review these pages so you get the most out of them. Lets click on WEST DIRECTORY-ZDV-DEN (click on the plus symbols next to the words to open the menus). The first row in the DEN chart is what is called LAND SOUTH configuration. All operations are in a southern direction, as would be necessary when the winds are out of the south. Coincidentally, this configuration is also the preferred configuration when the winds are calm, as the residents of eastern Colorado tend to complain the least when these runways are used. Most importantly, landing south allows the highest arrival and departure rate due to the runway set up. The IFR column lists the arrival rates in the worst weather (during snow storms, fog, etc). The separation rules change slightly when the weather is better (VFR column) and the airport can accept a lot more airplanes per hour. During a nice sunny day, when pilots can fly visual approaches, they are simply told which plane to follow on final approach, and separate themselves. Pilots are very good at this, and can decrease the space on final down to as little as 2 miles. Taxiways at the airport are angled so aircraft can exit at high speeds, which allows them to spend less time on the runway, and thus, trailing aircraft can follow at an even closer distance. Pilots can adjust their speed to ensure they touchdown soon after the preceding aircraft has exited the runway.
During weather that requires use of ILS approaches, aircraft cannot maintain visual separation with other traffic. Controllers need to vector planes onto the final approach course and must maintain anywhere between 3 and 5 miles between planes. Lets do some quick math (not really my strength, but bear with me). During busy periods, as many as 10 planes can be lined up on final approach. If they were in visual conditions, that would require approximately 20 miles. When using ILS approaches, controllers end up with a 30-40 mile line. Thats almost DOUBLE the amount of space required for the same amount of aircraft. At airports with only one runway (or when a single runway is used for both takeoff and landing), spacing on final approach may need to be 6 miles to allow departures to depart between arrivals. I'll let you realize how much less of an arrival rate that is compared to a runway solely used for visual approaches. Now let us head east, where airports that have dual use runways are much more common.
Lets click on EAST DIRECTORY-ZNY-LGA. The numbers here are much smaller, yet the demand is higher. During ideal operations, LGA has an arrival rate of 44. If the winds are strong out of the northeast, the arrival rate can drop as low at 18. Where do the other 26 arrivals go? They hold at the departure airport waiting for their place in line. If you look at the Holding Capacities chart below, you'll see that only a few aircraft can hold at each of the arrival fixes. This is due to airspace constraints at the en-route level. Remember, these sectors are also sequencing (and holding) arrivals to EWR, JFK, and TEB. Allow me to point out that the total arrival rate during perfect weather for all three Ny metro airports COMBINED (LGA - 44, EWR - 58, JFK - 68 = 170 arrivals per hour) is only TEN airplanes per hour more than Denver's one airport (160). Perhaps we'll discuss that issue some other time.
Traffic Management is in control of the big picture. They use these arrival rates to determine when planes should depart. The goal is to induce delays at the departure airport before the airplane even leaves the gate, which tends to be more comfortable, and much safer than airborne holding en-route. This doesn't always work out, however. Storms may move faster, slower, or in a different direction than expected, causing a different arrival rate at different times. Emergencies disrupt traffic flows without notice. Runways close for maintenance, greatly reducing capacity. And sometimes, controllers just need to go to the bathroom (sorry, couldn't resist!).
In the next post(s), I'll go more in depth about how changing arrival rates affect the system, and how weather BETWEEN your departure and arrival airport can greatly affect your flight as well.
DM
While it may seem that most delays are due to poor weather, and this is mostly true, the root of most delays stem from a lack of runways at your destination. I will stress that this lack of runways at our busiest airports is made most apparent during periods of bad weather, but is not exclusively due to weather. Also, some delays are due to bad weather in the en-route phase of flight, and have nothing to do with the weather at your origin OR destination. These are the delays that most puzzle the general public, in my opinion.
Let us start with some basics. Traffic Management has determined all the possible arrival and departure runway configurations at every major airport in the country. The use of each configuration depends on the visibility, cloud bases, and most importantly, the prevailing wind. Some configurations are capable of more operations per hour than others. The actual number of arrivals and departures per hour are publicly documented for each configuration at each major airport. They can be found here. I'll use this link to support a few examples.
Simply click on the plus signs next to East or West Directory, and then pick an ARTCC (Center) and then choose and airport. A chart should appear showing the relationship between each runway configuration and the arrival and departure rates in both optimal visual conditions and when instrument approach must be used. You'll notice the rates are different for visuals as opposed to when ILS approaches are in use, due to the increased separation required on final approach. I'll review these pages so you get the most out of them. Lets click on WEST DIRECTORY-ZDV-DEN (click on the plus symbols next to the words to open the menus). The first row in the DEN chart is what is called LAND SOUTH configuration. All operations are in a southern direction, as would be necessary when the winds are out of the south. Coincidentally, this configuration is also the preferred configuration when the winds are calm, as the residents of eastern Colorado tend to complain the least when these runways are used. Most importantly, landing south allows the highest arrival and departure rate due to the runway set up. The IFR column lists the arrival rates in the worst weather (during snow storms, fog, etc). The separation rules change slightly when the weather is better (VFR column) and the airport can accept a lot more airplanes per hour. During a nice sunny day, when pilots can fly visual approaches, they are simply told which plane to follow on final approach, and separate themselves. Pilots are very good at this, and can decrease the space on final down to as little as 2 miles. Taxiways at the airport are angled so aircraft can exit at high speeds, which allows them to spend less time on the runway, and thus, trailing aircraft can follow at an even closer distance. Pilots can adjust their speed to ensure they touchdown soon after the preceding aircraft has exited the runway.
During weather that requires use of ILS approaches, aircraft cannot maintain visual separation with other traffic. Controllers need to vector planes onto the final approach course and must maintain anywhere between 3 and 5 miles between planes. Lets do some quick math (not really my strength, but bear with me). During busy periods, as many as 10 planes can be lined up on final approach. If they were in visual conditions, that would require approximately 20 miles. When using ILS approaches, controllers end up with a 30-40 mile line. Thats almost DOUBLE the amount of space required for the same amount of aircraft. At airports with only one runway (or when a single runway is used for both takeoff and landing), spacing on final approach may need to be 6 miles to allow departures to depart between arrivals. I'll let you realize how much less of an arrival rate that is compared to a runway solely used for visual approaches. Now let us head east, where airports that have dual use runways are much more common.
Lets click on EAST DIRECTORY-ZNY-LGA. The numbers here are much smaller, yet the demand is higher. During ideal operations, LGA has an arrival rate of 44. If the winds are strong out of the northeast, the arrival rate can drop as low at 18. Where do the other 26 arrivals go? They hold at the departure airport waiting for their place in line. If you look at the Holding Capacities chart below, you'll see that only a few aircraft can hold at each of the arrival fixes. This is due to airspace constraints at the en-route level. Remember, these sectors are also sequencing (and holding) arrivals to EWR, JFK, and TEB. Allow me to point out that the total arrival rate during perfect weather for all three Ny metro airports COMBINED (LGA - 44, EWR - 58, JFK - 68 = 170 arrivals per hour) is only TEN airplanes per hour more than Denver's one airport (160). Perhaps we'll discuss that issue some other time.
Traffic Management is in control of the big picture. They use these arrival rates to determine when planes should depart. The goal is to induce delays at the departure airport before the airplane even leaves the gate, which tends to be more comfortable, and much safer than airborne holding en-route. This doesn't always work out, however. Storms may move faster, slower, or in a different direction than expected, causing a different arrival rate at different times. Emergencies disrupt traffic flows without notice. Runways close for maintenance, greatly reducing capacity. And sometimes, controllers just need to go to the bathroom (sorry, couldn't resist!).
In the next post(s), I'll go more in depth about how changing arrival rates affect the system, and how weather BETWEEN your departure and arrival airport can greatly affect your flight as well.
DM
April 10, 2007
Responsibility
"Because of the infinite variety of possible emergency situations, specific procedures cannot be prescribed. However, when you believe an emergency exists or is imminent, select and pursue a course of action which appears to be most appropriate under the circumstances and which most nearly conforms to the instructions in this manual."
As I begin Radar school, I have realized something odd. During the moments when the least amount of rules may apply (emergency situations), a controller's actions will be most scrutinized and second guessed. Take the paragraph above, straight out of Chapter 10 in the 7110.65. Almost everything a controller does during normal operations is dictated by rules prescribed by the 7110.65. Once an emergency situation is deemed to exist, there IS guidance contained in the rest of the chapter. However, it is limited, and most of it simply ensures that the proper coordination with other facilities will take place in a way that positively contributes to the outcome of the emergency.
Once a pilot declares an emergency, a controller is expected to use his or her best judgment to assist the pilot. Once the controllers are aware of the callsign, type of aircraft, the nature of the emergency and the pilots intentions, its up to the controllers to determine what additional information is needed, what additional information the pilot has time to, or the ability to, relay, and what action should be taken based on the information received. You'll notice I began the last sentence with "controllers" as plural. This is due to all that coordination that is required with other sectors and facilities. Emergencies require manpower. At the Center level, the coordination can be staggering. Surrounding sectors may need to be aware of the emergency so they can avoid that aircraft's current flight track, as well as potential track if it cannot maintain altitude or heading. Traffic intended to enter the sector may need to be diverted or delayed, as the sector handling the emergency may not be able to work a normal amount of traffic, since most of the attention is now focused on the emergency and all this coordination. Also, the next sector to work the airplane needs to be briefed on ALL information that pertains to the emergency. In addition, supervisors (ok, they're called Frontline Managers now) may need to call ahead to have fire equipment or ambulances standing by at the airport.
Often times, controllers will still be able to stick to the rule book when handling emergencies. This is not always the case. There are times when separation can not be maintained due to weather, aircraft malfunctions, or any other reason that would require declaration of an emergency. This does not preclude the controller from the primary mission, which is keeping planes from hitting other airplanes or terrain. Rules may need to be broken to keep people alive and planes intact. There is a big difference between ensuring standard separation of 5 miles, 1000 feet, and the planes actually, physically hitting each other. The latter is unacceptable, of course, and can quickly render the first standard a second priority.
The decision to start breaking rules at the expense of saving lives need to come in an instant. My instructors are doing their best to instill an ability to make decisions like these if and when they are needed. While we attempt to use a simulator to practice different techniques and tactics when dealing with emergencies, it's still a simulator. On top of this, stories of past situations are invaluable. Perhaps, one day, I'll call upon the memory of my instructor relating how they dealt successfully to a similar situation and act appropriately.
Oh, and don't forget: All of this split second decision making, with life or death possibly one move away; everything we say will be over-analyzed by folks ranging from fellow controllers, administration types, and possibly even the NTSB and the media if things don't go as planned. So, while the rules may have just gone out the window, someone's ability to remind me what I SHOULD have done is still alive and well. All in the interest of keeping the flying pilots and passengers alive and well. Thats why we're here, after all.
DM
As I begin Radar school, I have realized something odd. During the moments when the least amount of rules may apply (emergency situations), a controller's actions will be most scrutinized and second guessed. Take the paragraph above, straight out of Chapter 10 in the 7110.65. Almost everything a controller does during normal operations is dictated by rules prescribed by the 7110.65. Once an emergency situation is deemed to exist, there IS guidance contained in the rest of the chapter. However, it is limited, and most of it simply ensures that the proper coordination with other facilities will take place in a way that positively contributes to the outcome of the emergency.
Once a pilot declares an emergency, a controller is expected to use his or her best judgment to assist the pilot. Once the controllers are aware of the callsign, type of aircraft, the nature of the emergency and the pilots intentions, its up to the controllers to determine what additional information is needed, what additional information the pilot has time to, or the ability to, relay, and what action should be taken based on the information received. You'll notice I began the last sentence with "controllers" as plural. This is due to all that coordination that is required with other sectors and facilities. Emergencies require manpower. At the Center level, the coordination can be staggering. Surrounding sectors may need to be aware of the emergency so they can avoid that aircraft's current flight track, as well as potential track if it cannot maintain altitude or heading. Traffic intended to enter the sector may need to be diverted or delayed, as the sector handling the emergency may not be able to work a normal amount of traffic, since most of the attention is now focused on the emergency and all this coordination. Also, the next sector to work the airplane needs to be briefed on ALL information that pertains to the emergency. In addition, supervisors (ok, they're called Frontline Managers now) may need to call ahead to have fire equipment or ambulances standing by at the airport.
Often times, controllers will still be able to stick to the rule book when handling emergencies. This is not always the case. There are times when separation can not be maintained due to weather, aircraft malfunctions, or any other reason that would require declaration of an emergency. This does not preclude the controller from the primary mission, which is keeping planes from hitting other airplanes or terrain. Rules may need to be broken to keep people alive and planes intact. There is a big difference between ensuring standard separation of 5 miles, 1000 feet, and the planes actually, physically hitting each other. The latter is unacceptable, of course, and can quickly render the first standard a second priority.
The decision to start breaking rules at the expense of saving lives need to come in an instant. My instructors are doing their best to instill an ability to make decisions like these if and when they are needed. While we attempt to use a simulator to practice different techniques and tactics when dealing with emergencies, it's still a simulator. On top of this, stories of past situations are invaluable. Perhaps, one day, I'll call upon the memory of my instructor relating how they dealt successfully to a similar situation and act appropriately.
Oh, and don't forget: All of this split second decision making, with life or death possibly one move away; everything we say will be over-analyzed by folks ranging from fellow controllers, administration types, and possibly even the NTSB and the media if things don't go as planned. So, while the rules may have just gone out the window, someone's ability to remind me what I SHOULD have done is still alive and well. All in the interest of keeping the flying pilots and passengers alive and well. Thats why we're here, after all.
DM
March 23, 2007
March 18, 2007
You just got overrestricted.
I was reading an article the other day about how the current system gets easily overloaded, yet airspace is underutilized due to the use of standard restrictions. Someone unfamiliar with the day to day workings of the NAS concluded that a simple way to increase capacity and efficiency would be to simply allow URET (and other software not yet brainstormed into reality) to allow us to separate the actual airplanes, not just use a standard restriction which is designed to miss chunks of airspace where traffic tends to be most often.
Let me back up. Each sector is designed to do certain jobs (descend planes into other sectors, sequence traffic flows, provide approach services to small airports not within approach controls, etc). Each sector is then run by one to three controllers at a time, based on traffic load. In order to successfully accomplish the mission of the sector, limits are put upon it to decrease its complexity so that safety isn't compromised. There is only so much a controller can focus on at once. Most sectors don't have more than 5 or 6 main flows. Once a sector is deemed too complex or busy, a restriction is placed on the sector that feeds traffic to the sector in distress. Many of these restrictions are in place from 6am-11pm every day to establish a standardized flow so controllers and pilots can get used to them. Certain traffic landing at certain airports are forced out of some sectors and into others, so the complexity level in the busier sectors remains manageable. While it may not be the most efficient use of airspace, it IS the most orderly and the safer way to run things. The FAA has been having a hard time grasping that concept lately, but I'll let that discussion continue elsewhere.
Allow me to refer back to my analogy of working air traffic to not getting into an accident on the Interstate. Each lane is an available altitude, with speeds independent from the other lanes around it. Often times the best way to miss other cars is simply to change lanes. However, lets say you're in the right lane driving 50 miles per hour. The cars in the lane immediately to your left are driving 60 miles per hour, and to the left of that lane the cars are driving 75 miles per hour. Up ahead, the traffic is almost stopped due to an exit. The exit leads to a congested road that can't handle the traffic, and its backing up into your lane. So you move over one lane to the left. All of a sudden, you're the slow one. The cars behind you want to keep driving 60, so they move over one lane to the left, and now everyone is driving slower than they'd like, all because of some congestion that should only be affecting the right lane.
Adding another lane of through traffic may be a solution to the problem, but the traffic in the right hand lane still will affect all the others in a negative way. Often times, busy exits will exit sooner and create a frontage type road that is separate from the main highway. This separate exit road is similar to splitting off the sectors by altitude. You may exit a little sooner than you'd like, and likewise, descend a little sooner than desired for fuel efficiency, but it eliminates the traffic backups effecting the main flow of traffic.
The air traffic controller at the lower sector can worry about all that congestion running into the major airports, and the higher sector can worry about all the fast movers up at attitude.
If the system was controlled solely on the basis of efficiency, planes would do what their on board navigational computers told them to do. This mainly includes remaining at cruise altitude for as long as possible, and then dive bombing using idle thrust into the airport. While we cannot allow straight descent directly onto final approach, we do allow pilots to descend at their discretion to meet crossing restrictions at certain points along their route. These crossing restrictions are generally at the boundary with the next sector, or at the outer edge of the approach control. As controllers, we don't care how the aircraft descend, only they are level at the altitude issued at the location specified. Often times, aircraft will remain level until the last moment, and then descend at a quite impressive rate to make the restriction. Rates of around 4000 feet per minute are not uncommon. This is ironic, because pilots are SUPPOSED to descend at a "normal rate" in order to meet a restriction. A normal rate would be the rate if we simply said "descend and maintain xxxx". This is generally 1000-1500 feet per minute for jets. However, it is become expected that pilots will hang it up at altitude and then dive it in to the restriction.
I believe that in the future this desire to use high rates of descent into airports will serve as a basis for new airspace design. There is only one problem with this. It doesn't bode well for the lower and slower aircraft that will get in the way. Imagine a sports car in the far left lane suddenly cutting across four lanes of traffic to make the exit. Ok, now imagine a bus doing it! The only way that can be safe is if there is no other traffic around, but that would defeat the goal of increasing capacity, now, wouldn't it!?
We can't make the NAS efficient for everyone all the time, but we can slightly inconvenience a few planes here and there to make sure its SAFE and ORDERLY for everyone all the time. No sense saving gas if you never make it there.
DM
Let me back up. Each sector is designed to do certain jobs (descend planes into other sectors, sequence traffic flows, provide approach services to small airports not within approach controls, etc). Each sector is then run by one to three controllers at a time, based on traffic load. In order to successfully accomplish the mission of the sector, limits are put upon it to decrease its complexity so that safety isn't compromised. There is only so much a controller can focus on at once. Most sectors don't have more than 5 or 6 main flows. Once a sector is deemed too complex or busy, a restriction is placed on the sector that feeds traffic to the sector in distress. Many of these restrictions are in place from 6am-11pm every day to establish a standardized flow so controllers and pilots can get used to them. Certain traffic landing at certain airports are forced out of some sectors and into others, so the complexity level in the busier sectors remains manageable. While it may not be the most efficient use of airspace, it IS the most orderly and the safer way to run things. The FAA has been having a hard time grasping that concept lately, but I'll let that discussion continue elsewhere.
Allow me to refer back to my analogy of working air traffic to not getting into an accident on the Interstate. Each lane is an available altitude, with speeds independent from the other lanes around it. Often times the best way to miss other cars is simply to change lanes. However, lets say you're in the right lane driving 50 miles per hour. The cars in the lane immediately to your left are driving 60 miles per hour, and to the left of that lane the cars are driving 75 miles per hour. Up ahead, the traffic is almost stopped due to an exit. The exit leads to a congested road that can't handle the traffic, and its backing up into your lane. So you move over one lane to the left. All of a sudden, you're the slow one. The cars behind you want to keep driving 60, so they move over one lane to the left, and now everyone is driving slower than they'd like, all because of some congestion that should only be affecting the right lane.
Adding another lane of through traffic may be a solution to the problem, but the traffic in the right hand lane still will affect all the others in a negative way. Often times, busy exits will exit sooner and create a frontage type road that is separate from the main highway. This separate exit road is similar to splitting off the sectors by altitude. You may exit a little sooner than you'd like, and likewise, descend a little sooner than desired for fuel efficiency, but it eliminates the traffic backups effecting the main flow of traffic.
The air traffic controller at the lower sector can worry about all that congestion running into the major airports, and the higher sector can worry about all the fast movers up at attitude.
If the system was controlled solely on the basis of efficiency, planes would do what their on board navigational computers told them to do. This mainly includes remaining at cruise altitude for as long as possible, and then dive bombing using idle thrust into the airport. While we cannot allow straight descent directly onto final approach, we do allow pilots to descend at their discretion to meet crossing restrictions at certain points along their route. These crossing restrictions are generally at the boundary with the next sector, or at the outer edge of the approach control. As controllers, we don't care how the aircraft descend, only they are level at the altitude issued at the location specified. Often times, aircraft will remain level until the last moment, and then descend at a quite impressive rate to make the restriction. Rates of around 4000 feet per minute are not uncommon. This is ironic, because pilots are SUPPOSED to descend at a "normal rate" in order to meet a restriction. A normal rate would be the rate if we simply said "descend and maintain xxxx". This is generally 1000-1500 feet per minute for jets. However, it is become expected that pilots will hang it up at altitude and then dive it in to the restriction.
I believe that in the future this desire to use high rates of descent into airports will serve as a basis for new airspace design. There is only one problem with this. It doesn't bode well for the lower and slower aircraft that will get in the way. Imagine a sports car in the far left lane suddenly cutting across four lanes of traffic to make the exit. Ok, now imagine a bus doing it! The only way that can be safe is if there is no other traffic around, but that would defeat the goal of increasing capacity, now, wouldn't it!?
We can't make the NAS efficient for everyone all the time, but we can slightly inconvenience a few planes here and there to make sure its SAFE and ORDERLY for everyone all the time. No sense saving gas if you never make it there.
DM
March 10, 2007
I'm Super, thanks for asking.
There has long been a rivalry of sorts among aviation enthusiasts between Boeing and Airbus. Each airplane maker has its different fundamental culture and design philosophies. These differences are too complicated to discuss here, but they encourage both those individuals who fly them, and who wish they could fly them, to argue amongst themselves over which philosophy is better. Those who fly Boeing have coined the license plate holder: "If it ain't Boeing, I ain't going." I personally prefer Boeing. Call me a traditionalist... Or American?!
Well, Airbus is almost done with their new humongous A380. If you haven't seen what it looks like, just imagine a Boeing 777 with a full length second deck. It one-ups the B747. Very ambitious, and it has promised to increase efficiency on all levels for the airlines who fly it. There have been years of delays, ranging from electrical issues to new data that shows the plane may not be as structurally sound as Airbus claims it would be. A few airlines have given up on it, and pulled their orders recently.
On a personal note, I always complain about airlines that fly 15 flights a day between two cities, with many of the flights in small aircraft (as opposed to less flights with larger aircraft) just so they can tell their customers "we fly there 15 times a day, don't worry, you'll make it there". This is one of the reasons there are so many delays. The reason this is frustrating is because there are only so many runways, and there is only so much airspace, and it seems like a waste of space. In the en-route environment, every airplane looks the same on the scope, and we always need 5 miles and 1000 feet regardless if its a B767 or a CRJ. Once closer to the airport, the approach controllers need an extra mile or two here and there for the bigger planes, but its not as much as adding another plane.
Needless to say, I really didn't have any opinion one way or the other on the new big-bus. It seemed like a good idea to me, especially if airlines would replace thier two 757s with one A380. I take that back, you'd get to replace 4 757s with one A380. Now, I'm sure thats not the plan, but I can dream of less targets out there. Its mainly going to be flown in Europe and Asia, but we'll see a few of them here and there.
With that said, Airbus is flying a publicity flight into JFK this month to show off their new bird. I got to take time out of my busy schedule to attend a briefing on the "event" a few days ago. Turns out, the A380 isn't as efficient as it would seem. Enroute still only needs 5 miles, 1000 feet. But in approach control (and when Center is sequencing to handoff to approach control), the spacing increases to 10 miles, 1000 feet for wake turbulence. Thats 3 times the spacing needed between two 737s. Thats twice the spacing needed between two 747s. And frankly, at the Center, I think we'll be cautious about putting another airplane behind it and below it, regardless of how legal the separation remains.
So, the moral of my story:
This massive plane that is like two airplanes in one, needs to be treated like two airplanes for separation. It should be a winner. Oh, wait, I almost forgot. Our current weight/wake turbulence categories of Small, Large, Heavy is getting a new classification: Super. Look it up on March 15. It'll be right there in the 7110.65. "traffic 2 oclock, 6 miles, northbound, at 12000, a super A380, caution wake turbulence". Sounds like a PR move by Airbus to me. They'll need all the help they can get.
Well, Airbus is almost done with their new humongous A380. If you haven't seen what it looks like, just imagine a Boeing 777 with a full length second deck. It one-ups the B747. Very ambitious, and it has promised to increase efficiency on all levels for the airlines who fly it. There have been years of delays, ranging from electrical issues to new data that shows the plane may not be as structurally sound as Airbus claims it would be. A few airlines have given up on it, and pulled their orders recently.
On a personal note, I always complain about airlines that fly 15 flights a day between two cities, with many of the flights in small aircraft (as opposed to less flights with larger aircraft) just so they can tell their customers "we fly there 15 times a day, don't worry, you'll make it there". This is one of the reasons there are so many delays. The reason this is frustrating is because there are only so many runways, and there is only so much airspace, and it seems like a waste of space. In the en-route environment, every airplane looks the same on the scope, and we always need 5 miles and 1000 feet regardless if its a B767 or a CRJ. Once closer to the airport, the approach controllers need an extra mile or two here and there for the bigger planes, but its not as much as adding another plane.
Needless to say, I really didn't have any opinion one way or the other on the new big-bus. It seemed like a good idea to me, especially if airlines would replace thier two 757s with one A380. I take that back, you'd get to replace 4 757s with one A380. Now, I'm sure thats not the plan, but I can dream of less targets out there. Its mainly going to be flown in Europe and Asia, but we'll see a few of them here and there.
With that said, Airbus is flying a publicity flight into JFK this month to show off their new bird. I got to take time out of my busy schedule to attend a briefing on the "event" a few days ago. Turns out, the A380 isn't as efficient as it would seem. Enroute still only needs 5 miles, 1000 feet. But in approach control (and when Center is sequencing to handoff to approach control), the spacing increases to 10 miles, 1000 feet for wake turbulence. Thats 3 times the spacing needed between two 737s. Thats twice the spacing needed between two 747s. And frankly, at the Center, I think we'll be cautious about putting another airplane behind it and below it, regardless of how legal the separation remains.
So, the moral of my story:
This massive plane that is like two airplanes in one, needs to be treated like two airplanes for separation. It should be a winner. Oh, wait, I almost forgot. Our current weight/wake turbulence categories of Small, Large, Heavy is getting a new classification: Super. Look it up on March 15. It'll be right there in the 7110.65. "traffic 2 oclock, 6 miles, northbound, at 12000, a super A380, caution wake turbulence". Sounds like a PR move by Airbus to me. They'll need all the help they can get.
February 11, 2007
What exactly does a D-side do?
There are two forms of separation used in air traffic. Radar and Non-radar. While we are almost always using radar data to separate aircraft, we still use forms of separation that do not require radar to get the job done. For instance, any time we have vertical separation (two planes at two different altitudes), that is considered Non-radar separation. The radar comes in when we have planes not yet at different altitudes, but we can assure that by the time they are within 5 miles of each other the vertical separation is there. We can keep planes at the same altitude if we turn one or both of them away from each other and thus use lateral separation.
Whenever I am driving to work, I tend to see things around me as they would relate to how we control airplanes. For example, each lane in of the highway is an altitude. Cars in the right lane are always separated from cars in the middle lane, which are always separated from the cars in the left lane. The key is that each lane is going its own speed. If one car in the right lane slows down, the rest of the cars in the right lane must slow down as well, or, move into the middle lane so they can speed up. In addition, when cars are exiting or entering the highway via the right lane, the cars in the right lane must use their judgment and adjust their speed accordingly to allow the cars to enter or exit without hitting them. In air traffic, this is Radar separation. Determining the sequence and using vectors and speed control to make it work as it happens is the job of the Radar controller, the controller talking to the airplanes.
The other option is to simply switch lanes to the middle lane where you can then go your own pace and there is much less work involved. Cars can get on easily, and you don't have to slow down, speed up, and get stressed out over how to let everyone in. Remember the analogy, changing lanes is like changing altitudes. The key is the look ahead, see the cars approaching on the on-ramp, and switch lanes to make life easier for all. This is the job of the D-side (Radar associate/data controller). D-sides watch the edges of the airspace for aircraft approaching the sector which are in conflict with other planes either already inside the sector or approaching it from other sectors (aircraft which are being handed off from the same sector must be separated when they enter another sector, but very often, aircraft converge into your sector from two or three different sectors). The D-side must then call the other sector on the land line and issue control instructions to that aircraft to change altitudes so they are separated by altitude when they enter the sector.
It is not always that easy, though often times it is. The D-side works with the Radar controller to make a crucial decision as to which of the two aircraft to move. For example, lets assume two aircraft are converging over Ithaca, NY. One is coming from New York Center, the other from Cleveland Center. One aircraft is landing Boston at FL350, the other is flying to Frankfort at FL350. Chances are the overseas flight can't go any higher due to fuel weight, so lets descend the Boston guy. Ideally, we try to keep planes at the correct altitude for direction, so FL330. But if there is a HPN arrival below at Fl330, FL340 may have to be used. This is the basic job function of a D-side.
In the last few years, D-sides have been called upon to make more radar decisions. Perhaps giving the overseas flight a shortcut to the right would cause the flight paths not to cross. Maybe a similar shortcut would make the flight paths cross 40 miles east of where they originally would have crossed in conflict, allowing the radar controller to descend the aircraft arriving HPN first, then incrementally descend the BOS arrival on top of him. Sometimes the best bet is to turn one of the planes 30 degrees off course to fall behind the other aircraft. It is the D-side's job to FIND the conflict and advise the Radar controller. Sometimes the radar controller has a definite plan, and simply informs the D-side what they would like done, other times its a team effort to come up with the best plan.
In addition, the D-side keeps track of all the flight plans on the URET screen. The URET will often alert the D-side of potential conflicts between aircraft with Red boxes. This does not guarantee that the aircraft will be in conflict, nor does a lack of conflict guarantee there won't be a conflict. The key is to understand how each sector works and how that will affect each aircraft. The Frankfort and Boston example is straightforward, but it gets much more complicated when you have to decide between JFK and PIT, PHL and HPN, ALB and SWF, BTV and PSM, MDT and MGW. The key is knowing exactly what each aircraft must do in order to leave your sector correctly, and what the next sector can and won't accept. Aircraft performance and weather also play key rolls in the decision making.
Finally, D-sides handle most, if not all, land line calls to other sectors. These behind-the-scenes calls are to coordinate approval requests, pointouts, and anything else that is out of the ordinary and must be talked over with the other sector.
If you have any questions, send away to deltamike172@hotmail.com
Whenever I am driving to work, I tend to see things around me as they would relate to how we control airplanes. For example, each lane in of the highway is an altitude. Cars in the right lane are always separated from cars in the middle lane, which are always separated from the cars in the left lane. The key is that each lane is going its own speed. If one car in the right lane slows down, the rest of the cars in the right lane must slow down as well, or, move into the middle lane so they can speed up. In addition, when cars are exiting or entering the highway via the right lane, the cars in the right lane must use their judgment and adjust their speed accordingly to allow the cars to enter or exit without hitting them. In air traffic, this is Radar separation. Determining the sequence and using vectors and speed control to make it work as it happens is the job of the Radar controller, the controller talking to the airplanes.
The other option is to simply switch lanes to the middle lane where you can then go your own pace and there is much less work involved. Cars can get on easily, and you don't have to slow down, speed up, and get stressed out over how to let everyone in. Remember the analogy, changing lanes is like changing altitudes. The key is the look ahead, see the cars approaching on the on-ramp, and switch lanes to make life easier for all. This is the job of the D-side (Radar associate/data controller). D-sides watch the edges of the airspace for aircraft approaching the sector which are in conflict with other planes either already inside the sector or approaching it from other sectors (aircraft which are being handed off from the same sector must be separated when they enter another sector, but very often, aircraft converge into your sector from two or three different sectors). The D-side must then call the other sector on the land line and issue control instructions to that aircraft to change altitudes so they are separated by altitude when they enter the sector.
It is not always that easy, though often times it is. The D-side works with the Radar controller to make a crucial decision as to which of the two aircraft to move. For example, lets assume two aircraft are converging over Ithaca, NY. One is coming from New York Center, the other from Cleveland Center. One aircraft is landing Boston at FL350, the other is flying to Frankfort at FL350. Chances are the overseas flight can't go any higher due to fuel weight, so lets descend the Boston guy. Ideally, we try to keep planes at the correct altitude for direction, so FL330. But if there is a HPN arrival below at Fl330, FL340 may have to be used. This is the basic job function of a D-side.
In the last few years, D-sides have been called upon to make more radar decisions. Perhaps giving the overseas flight a shortcut to the right would cause the flight paths not to cross. Maybe a similar shortcut would make the flight paths cross 40 miles east of where they originally would have crossed in conflict, allowing the radar controller to descend the aircraft arriving HPN first, then incrementally descend the BOS arrival on top of him. Sometimes the best bet is to turn one of the planes 30 degrees off course to fall behind the other aircraft. It is the D-side's job to FIND the conflict and advise the Radar controller. Sometimes the radar controller has a definite plan, and simply informs the D-side what they would like done, other times its a team effort to come up with the best plan.
In addition, the D-side keeps track of all the flight plans on the URET screen. The URET will often alert the D-side of potential conflicts between aircraft with Red boxes. This does not guarantee that the aircraft will be in conflict, nor does a lack of conflict guarantee there won't be a conflict. The key is to understand how each sector works and how that will affect each aircraft. The Frankfort and Boston example is straightforward, but it gets much more complicated when you have to decide between JFK and PIT, PHL and HPN, ALB and SWF, BTV and PSM, MDT and MGW. The key is knowing exactly what each aircraft must do in order to leave your sector correctly, and what the next sector can and won't accept. Aircraft performance and weather also play key rolls in the decision making.
Finally, D-sides handle most, if not all, land line calls to other sectors. These behind-the-scenes calls are to coordinate approval requests, pointouts, and anything else that is out of the ordinary and must be talked over with the other sector.
If you have any questions, send away to deltamike172@hotmail.com
February 3, 2007
Got a map? That may not help....
This post could technically be labeled "Little Airports Part 3", but I chose a unique name instead, as this will act as a transition to another topic.
In my area at Boston Center, we have a joke about the 40N airport. The joke is on Area B (the controllers to our northeast) not knowing what to do with such aircraft. The 40N airport is the Chester County airport in PA, about 30 miles west of Philadelphia (and yes, its completely ironic that the Outer Marker to the ILS Runway 29 approach is named MOSES). Very often, a corporate pilot will be flying along fat, dumb and sufficiently pleased with the ride at FL360 over Albany. Area B flashes the aircraft to us, and we make a phone call to them informing them that they should "treat it like a Philly". They then scramble to dive bomb the aircraft down to FL260 so that we can deliver the aircraft to ZNY over DNY at FL190, just like a Philly. The pilot checks in with us a little perturbed at the fact that we made him spill his coffee just so he could descend sooner than desired.
While 40N is near PHL, why do we have to treat arrivals exactly like a PHL lander? The answer is simple: 40N is within the boundaries of the PHL Approach Control. Every other airport within airspace owned by PHL Approach must be treated in the exact same fashion. While this may seem unfair, and not always the most efficient, it simplifies one aspect of a very complicated system. The only exception to this rule is when the airport inside the approach control is busy enough to justify its own routing for the sake of keeping those aircraft safely away from the aircraft operating at the main airport. Basically, if there are enough planes to get in the way of the main flow, another secondary flow is created. Often, this secondary flow is used for all other airports OTHER THAN the main airport.
Examples: TEB/MMU/CDW are busy enough to require they're own flow apart from EWR. BOS has its own flows into A90 TRACON, and the Satellite airports have another flow which is handed off to a different A90 controller than the BOS arrivals.
But lets get back to the smaller airports. How can you tell which "category" an airport falls into?
Lets take a look at 3 airports in Boston Center, all within 20 miles of each other, but all three are treated completely different because of the airspace structure.
KORE - Orange, MA
KFIT - Fitchburg, MA
KORH - Worcester, MA (pronounced WHUST-uh?)
ORE is a small airport located in an area where ZBW-GDM Sector owns to the surface. This Sector sequences BOS area arrivals, and serves as an approach control for EEN, ORE, and GDM airports. FIT is an airport just inside the A90 TRACON, and thus is treated as a BOS Satellite. ORH is located inside of BDL approach (Y90 TRACON).
Lets see what happens when three aircraft approach from the west of ALB VOR inbound to these three airports.
The FIT arrival is routed via ALB..GDM.V431.LOBBY..FIT and issued a restriction to cross 40 west of ALB at FL290, descended to FL230 about 40 miles east of ALB, and then descended to cross BRONC at 6000, unless Runway 14 is requested, in which case, the arrival is descended lower for the approach.
The ORE arrival is routed via ALB..EEN/GDM..ORE (if not just direct ORE) and descended to FL230 about 30 west of ALB (vicinity of SWEDE), then descended to 11000 40 east of ALB, and then descended for approach by the GDM sector. This flow is meant to be below the BOS Satellite arrivals, avoiding the high altitude sector that feeds the GDM Sector.
The ORH arrival is routed south of ALB via RKA.SWEDE1.ORH. This may be the most obvious of the three routings, as ORH is listed on the SWEDE1 chart. These arrivals cross SWEDE anywhere between FL230 and FL180, then descended to 11000 and handed off to Y90 TRACON about 30 miles southeast of ALB.
What was the question again? Here's the answer:
If you're not sure what route to file into a small airport, take a look at the approach charts. Which facility has its frequencies listed on the chart? That main facility is your clue to how "you'll be treated" and how to file your flight plan. That's how controllers like me figure out where you're going!
DM
In my area at Boston Center, we have a joke about the 40N airport. The joke is on Area B (the controllers to our northeast) not knowing what to do with such aircraft. The 40N airport is the Chester County airport in PA, about 30 miles west of Philadelphia (and yes, its completely ironic that the Outer Marker to the ILS Runway 29 approach is named MOSES). Very often, a corporate pilot will be flying along fat, dumb and sufficiently pleased with the ride at FL360 over Albany. Area B flashes the aircraft to us, and we make a phone call to them informing them that they should "treat it like a Philly". They then scramble to dive bomb the aircraft down to FL260 so that we can deliver the aircraft to ZNY over DNY at FL190, just like a Philly. The pilot checks in with us a little perturbed at the fact that we made him spill his coffee just so he could descend sooner than desired.
While 40N is near PHL, why do we have to treat arrivals exactly like a PHL lander? The answer is simple: 40N is within the boundaries of the PHL Approach Control. Every other airport within airspace owned by PHL Approach must be treated in the exact same fashion. While this may seem unfair, and not always the most efficient, it simplifies one aspect of a very complicated system. The only exception to this rule is when the airport inside the approach control is busy enough to justify its own routing for the sake of keeping those aircraft safely away from the aircraft operating at the main airport. Basically, if there are enough planes to get in the way of the main flow, another secondary flow is created. Often, this secondary flow is used for all other airports OTHER THAN the main airport.
Examples: TEB/MMU/CDW are busy enough to require they're own flow apart from EWR. BOS has its own flows into A90 TRACON, and the Satellite airports have another flow which is handed off to a different A90 controller than the BOS arrivals.
But lets get back to the smaller airports. How can you tell which "category" an airport falls into?
Lets take a look at 3 airports in Boston Center, all within 20 miles of each other, but all three are treated completely different because of the airspace structure.
KORE - Orange, MA
KFIT - Fitchburg, MA
KORH - Worcester, MA (pronounced WHUST-uh?)
ORE is a small airport located in an area where ZBW-GDM Sector owns to the surface. This Sector sequences BOS area arrivals, and serves as an approach control for EEN, ORE, and GDM airports. FIT is an airport just inside the A90 TRACON, and thus is treated as a BOS Satellite. ORH is located inside of BDL approach (Y90 TRACON).
Lets see what happens when three aircraft approach from the west of ALB VOR inbound to these three airports.
The FIT arrival is routed via ALB..GDM.V431.LOBBY..FIT and issued a restriction to cross 40 west of ALB at FL290, descended to FL230 about 40 miles east of ALB, and then descended to cross BRONC at 6000, unless Runway 14 is requested, in which case, the arrival is descended lower for the approach.
The ORE arrival is routed via ALB..EEN/GDM..ORE (if not just direct ORE) and descended to FL230 about 30 west of ALB (vicinity of SWEDE), then descended to 11000 40 east of ALB, and then descended for approach by the GDM sector. This flow is meant to be below the BOS Satellite arrivals, avoiding the high altitude sector that feeds the GDM Sector.
The ORH arrival is routed south of ALB via RKA.SWEDE1.ORH. This may be the most obvious of the three routings, as ORH is listed on the SWEDE1 chart. These arrivals cross SWEDE anywhere between FL230 and FL180, then descended to 11000 and handed off to Y90 TRACON about 30 miles southeast of ALB.
What was the question again? Here's the answer:
If you're not sure what route to file into a small airport, take a look at the approach charts. Which facility has its frequencies listed on the chart? That main facility is your clue to how "you'll be treated" and how to file your flight plan. That's how controllers like me figure out where you're going!
DM
January 18, 2007
Automated Traffic Control?
URET (User Request Evaluation Tool) is the strip replacement system installed last year at Boston Center. It was already operational at most other ARTCC's, as we were in the next to last group to receive it. The system is basically a parallel computer program that runs with our HOST computer and stores flight plan information, weather data, updates the data with our inputs, and displays it on an LCD screen which was installed where our strip bays once were. There are some quirks and bugs in it, which distract us momentarily, but once you learn what they are, you assume it will screw up when you do certain things, and you ignore them or work around them as they happen. Some day, the bugs may be fixed; we are waiting for the computer techs to learn how to fix URET (they were last on the list to learn how to use URET and fix it, ironically).
And while there are plenty of bugs in the system's internal programming features, the issues extend far beyond that when you consider the possible future usage of the program.
I will NOT say that I think that URET will someday run air traffic. I do believe that the attempt to use URET to aid another automated program to replace air traffic controllers will occur in the near future. It would be at least a two step process. URET has a "probe" function at its core, which scans traffic based on current position, route of flight, current flight track, estimated wind at altitude, filed airspeed, and aircraft performance characteristics. This current probe function could be used to predict, based on a flight's scheduled departure time, all aircraft it would become a potential conflict for before it even takes off. This probe is relatively very simple, as it cannot create an alternative route or altitude that will eliminate the conflict. A second program would have to developed to create the plan of action. In a previous post, I wrote of a program being developed that could run sectors better than any human. I do not know much about this tested (its still in testing behind closed doors), but the results seeping out from under the closed door indicate the program is very good at maintaining current separation standards at much higher rates of traffic though current sectors. I wonder, though, if it can maintain 15 miles in trail separation for aircraft going to certain destinations? What would happen when the weather is crappy in the summer, and planes REQUEST something, such as a weather deviation, or a lower altitude for turbulence? What would happen if aircraft are flying slower to save gas?
For all you savvy fliers out there, you may have noticed when the captain comes on the PA to announce that "they apologize for the delay at the gate, but we're gonna try to make up time in the air". How could this be? It may be a shock to realize that aircraft don't always fly as fast as they can go. The slower they go, the less gas they guzzle. An interesting side note: Airlines that aren't doing so well financially fly slower than those that make money occasionally.
Unfortunately, URET doesn't pick up on this, since its a computer. Airlines always file the same flight plan every day. They amend things like the route or type of aircraft when needed, though rarely change the filed airspeed, regardless if the fight that day is going slower to save gas, or faster to make up for the ground delay.
Now, things like weather, emergencies, and spacing are all widely regarded as "the human element" when there is talk of computers taking over the world or air traffic. Yet, the speed of aircraft is never discussed, but when examples offered, the responce is typically, "oh, thats just the human element".
I'll close with an example:
Two aircraft are going to hit over SYR. They are N108KC, a Cessna Citation jet from Manchester to someplace west of SYR at FL360, and ACA995 (Air Canada) an A319 (Airbus 319) from Montreal to Mexico City climbing to FL360. When the aircraft were just entering the sector (N108KC was about 60 miles east of SYR, ACA995 was about 90 miles northeast of SYR), the two aircraft were determined to be in conflict by the controllers working the sector (myself and the radar controller). Since ACA995 was still climbing out of Montreal, we simply stopped his climb at FL350. URET showed no conflict alert whatsoever. It took the wind into account correctly, but failed to realize that the actual airspeed of N108KC was significantly less than the filed airspeed. Thus, since URET doesn't actually track the aircraft's datablock, it didn't realize the Citation wasn't as far along his route as it thought (they don't call it a "Slowtation" for nothing). Come to think of it, HOST thought the plane was farther along that it was, as well. When we drew the Route line on the radar screen, it showed the start of the line well ahead of the actual target of N108KC. The datablock still tracks the actual target of the aircraft, but the rest of the computer thinks the plane is farther along, and things like that affect automation such as handoffs to other facilities in ways that aren't relevant to this discussion. So, while the HOST and URET assume that N108KC will pass 15 miles in front of ACA995, the targets merged perfectly, directly overhead SYR, but with 1000 feet vertical separation.
Too bad for the human element in our world lest we could get computers to run it for us.
DM
And while there are plenty of bugs in the system's internal programming features, the issues extend far beyond that when you consider the possible future usage of the program.
I will NOT say that I think that URET will someday run air traffic. I do believe that the attempt to use URET to aid another automated program to replace air traffic controllers will occur in the near future. It would be at least a two step process. URET has a "probe" function at its core, which scans traffic based on current position, route of flight, current flight track, estimated wind at altitude, filed airspeed, and aircraft performance characteristics. This current probe function could be used to predict, based on a flight's scheduled departure time, all aircraft it would become a potential conflict for before it even takes off. This probe is relatively very simple, as it cannot create an alternative route or altitude that will eliminate the conflict. A second program would have to developed to create the plan of action. In a previous post, I wrote of a program being developed that could run sectors better than any human. I do not know much about this tested (its still in testing behind closed doors), but the results seeping out from under the closed door indicate the program is very good at maintaining current separation standards at much higher rates of traffic though current sectors. I wonder, though, if it can maintain 15 miles in trail separation for aircraft going to certain destinations? What would happen when the weather is crappy in the summer, and planes REQUEST something, such as a weather deviation, or a lower altitude for turbulence? What would happen if aircraft are flying slower to save gas?
For all you savvy fliers out there, you may have noticed when the captain comes on the PA to announce that "they apologize for the delay at the gate, but we're gonna try to make up time in the air". How could this be? It may be a shock to realize that aircraft don't always fly as fast as they can go. The slower they go, the less gas they guzzle. An interesting side note: Airlines that aren't doing so well financially fly slower than those that make money occasionally.
Unfortunately, URET doesn't pick up on this, since its a computer. Airlines always file the same flight plan every day. They amend things like the route or type of aircraft when needed, though rarely change the filed airspeed, regardless if the fight that day is going slower to save gas, or faster to make up for the ground delay.
Now, things like weather, emergencies, and spacing are all widely regarded as "the human element" when there is talk of computers taking over the world or air traffic. Yet, the speed of aircraft is never discussed, but when examples offered, the responce is typically, "oh, thats just the human element".
I'll close with an example:
Two aircraft are going to hit over SYR. They are N108KC, a Cessna Citation jet from Manchester to someplace west of SYR at FL360, and ACA995 (Air Canada) an A319 (Airbus 319) from Montreal to Mexico City climbing to FL360. When the aircraft were just entering the sector (N108KC was about 60 miles east of SYR, ACA995 was about 90 miles northeast of SYR), the two aircraft were determined to be in conflict by the controllers working the sector (myself and the radar controller). Since ACA995 was still climbing out of Montreal, we simply stopped his climb at FL350. URET showed no conflict alert whatsoever. It took the wind into account correctly, but failed to realize that the actual airspeed of N108KC was significantly less than the filed airspeed. Thus, since URET doesn't actually track the aircraft's datablock, it didn't realize the Citation wasn't as far along his route as it thought (they don't call it a "Slowtation" for nothing). Come to think of it, HOST thought the plane was farther along that it was, as well. When we drew the Route line on the radar screen, it showed the start of the line well ahead of the actual target of N108KC. The datablock still tracks the actual target of the aircraft, but the rest of the computer thinks the plane is farther along, and things like that affect automation such as handoffs to other facilities in ways that aren't relevant to this discussion. So, while the HOST and URET assume that N108KC will pass 15 miles in front of ACA995, the targets merged perfectly, directly overhead SYR, but with 1000 feet vertical separation.
Too bad for the human element in our world lest we could get computers to run it for us.
DM
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