September 19, 2008

Overtaking me

Ok, back to reality. It was busy yesterday, and there was a lot of in-trail spacing going on. I had a few instances that are my least favorite in terms of decision making...The back plane is going WAY faster than the front plane, but they're definitely not tied either. Do I let the back plane run fast and overtake the slower plane, or should I just slow the back one and keep it second? Sometimes its really obvious. These two times were not:

1 - Scandinavian heavy jet approaching HNK from the north. A Porter Dash 8 prop (and yet we have to space it with jets because they are capable of 250 knots)incoming from the west, both landing Newark. There is 20 miles in trail. The heavy jet from the north is going over the ground 150 knots faster than the Dash 8, but the Dash 8 is 4 miles ahead. I make my decision and stick to it. I tell the A330 from overseas to keep it going 310 knots of faster, and slow the Dash 8 to slowest practical (220 knots). I turn the Dash 8 left to follow the A330, but the wind is at the Dash 8's tail more now. I have an Albany lander in there that I get below both Newarks, and then a White Plains (HPN) comes screaming in from the high sector. I step the HPN down as the A330 is descending, but I'm not getting the spacing I was hoping for, as the A330 is loosing tailwind now that he's pushed down below the HPN. The next sector approved a shortcut for the A330, but that new heading gets in the way of the HPN. So we finally settle on a new shortcut, and the planes diverge a little more.

I have a little conversation with myself about whether or not those overtakes really are worth the effort. An hour later....back at DNY sector:

2 - This one involved TWO Dash 8s and an E170 jet. It starts off obvious. The first Dash 8 is about 6 miles in front of the E170, flying 120 knots slower. I'm going to gain 2 miles a minute, and I need to make up at least 11 miles to finish the overtake. I have more than 5.5 minutes to the end of my sector, so its settled then. I assign the Dash 8 slowest practical again and get a few more knots difference working for me. Then NY center flashes me another Dash 8, 5 miles in front of the first one, at 17000. Well well well. So I get control to turn both Dash 8s and I go to a 050 heading. The E170 is really making up ground now. So I turn the two Dash 8s back to HNK on course. Then I realize I STILL have 20 miles in trail to Newark. Crap. So I turn the two Dash 8s back to 050 headings. "I need a few more miles". Like 15 more on the first one, and 30 more on the back one. I couldn't turn that second one back due south like I wanted to because I had to push a TEB jet down to 15000 below the EWR arrivals. It didn't feel very pretty, but it ended up OK.

Today, I'm just gonna slow the back guy and vector to keep my spacing, I think. I was 0-2 for overtakes yesterday. I don't like those odds.



Geoff said...

I wasn't aware of the FlightAware site before. Very cool (though altitude would make it even more interesting). Thanks.

Teller said...

I stumbled upon your blog tonight from Matt's (The Flight Life), and am quite excited to catch up over the next day or two - much to the wife's chagrin. I was quite taken with this post, though, as I remember this day with the two Dashes and the 170; we were wondering why we had to fly 050 on this route. The things our TCAS just doesn't tell us!