So close yet so far...

When it comes to Air Traffic, I am always on the lookout for new information to learn. Controllers in my area will give me a lot of crap for knowing too much about things I have no business knowing. Last week someone was angered about another area's move and yells out to no one in particular, maybe the wall, "Hey, don't be short cutting guys when there's an EDCT for construction..." I blurted out "To Minnie?" "Uh, yeah, how the *#&^ did you know that?" Shrug, "this buddy of mine was writing about it in HIS blog..."

Anytime I go to a new city, I try to get a tour of an ATC facility there. Most facilities have their little quirks and oddities that never cease to fascinate me. Four years later, I think I have finally found Boston Center's quirk.

Boston Center has 5 areas, A-E. In training, we would just randomly go and spend time in other area's to see traffic from their perspective. I personally spent time in Area B and E a few times, and occasionally stop and talk to people in Area D. Until today, I had never stepped foot inside Area C. They are one of the busiest areas in the Center, if not THE busiest. My area only works with one of their sectors (BOSOX) directly. The rest, while only 40-50 miles from my area, is a mystery. I know they work JFK arrivals from the northeast. They work more BOS arrivals than we do and about half the BOS departures. The Hampton Sector goes crazy in the summer. Boston High works tons of overseas departures. Other than that, that's it.

So, I had the distinct pleasure of being RM's special guest as I was sidetracked on my way out of the control room to go on break. How could I turn her invitation down!? I got a quick overview of PVD sector, which works all the BOS arrivals, and BOSOX, which works the departures and takes PVD arrivals from the ALB sector (my ALB sector!) and descends them into PVD approach (hey! I just worked that guy!). They weren't very busy, so we chatted about nerdy controller stuff. They use 3 mile separation in a big chunk of their area. Area A doesn't use 3 mile separation...YET. They're working on it.

About 99 percent of En-route Center airspace requires 5 miles separation and 1000 feet vertical below FL410. This 5 mile requirement is necessary because we combine numerous long range radar data into one "mosaic" display on our screen. There is no radar sweep or anything like that. There are a few places where the computer will only use one radar site at a time, and as long as the plane is below FL180 and within 40 miles of the single radar site being used, we can use 3 miles, just like an approach control. Boston Center has more 3 mile separation areas than any other Center. At least, that is what they tell us to make us feel special.

The same 40 mile rule applies to approach controls. However, since approach controls are centered around their radar, only small portions of their airspace exist beyond the 40 mile bubble. Thus, 5 mile separation is considered more of an exception to their 3 mile, 1000 foot rule.

The Providence (PVD) sector in Area C descends Boston arrivals to cross PVD VOR at 11000, who are then handed off to Boston Approach. PVD sector uses 3 mile separation within 40 miles of PVD airport's radar site. Providence, RI is more than 40 miles from Boston (42.7 according to Airnav), so the approach control they hand off to requires 5 miles at that point of transfer. While the Center can allow planes to get within 3 miles as they descend into Boston, they must take action to regain 5 miles again before handoff to Approach. This seems to be the only instance in the US where the En-route Center requires less separation than the approach control taking the hand off below them!

If anyone around the country or the world has any examples of this occurring elsewhere, please comment!

Till next time....

DM

PHOTO NOTE:
Thanks as always to SkyVector.
Light Blue shows the Boston arrivals.
Dark Green shows the PVD arrivals that descend under the Boston arrivals.
Boston Departures go out over LUCOS, BOSOX to BDL and GLYDE to BAF. Consider it a Where's Waldo of fixes!