Tuesday, October 22, 2013

FAA History Lesson -- October 22, 2003

From the Update to FAA Historical Chronology 1997-2012 (A .pdf file)

"FAA issued a new rule reducing the minimum vertical separation between aircraft from the current 2,000 feet to 1,000 feet for all aircraft flying between 29,000 feet and 41,000 feet. RVSM implementation would significantly increase the routes and altitudes available and thus allow more efficient routings that would save time and fuel. FAA planned to implement Reduced Vertical Separation Minima (RVSM) procedures on January 20, 2005, to give airlines and other aircraft operator's time to install the more accurate altimeters and autopilot systems needed to ensure the highest level of safety. The long-awaited rule – FAA initiated the process with a notice of proposed rulemaking in May 2002 – detailed equipment requirements, including dual altimeters and a more advanced autopilot system. Aircraft equipped with traffic alert and collision avoidance system version II (TCAS II) had to be updated with new software, compatible with RVSM operations. (See May 10, 2002; November 26, 2003.) "

This is one of the most effective changes the FAA made in my entire career. We had two sectors at ZTL (Atlanta Center) that were among the toughest in the facility -- SALEM and GA HIGH (Georgia High). They were both abominations. The airspace needed to be totally redesigned but ZTL was fighting the natural order of busy, hub airspace to trend towards long, narrow corridors working arrivals and departures into and out of the hub (Atlanta in this case.) With the number of thunderstorms ZTL has to deal with, this was understandable (if futile.)

Anyway, SPA HIGH (Spartanburg, SC) worked the east departures out of ATL (Atlanta) from FL240 through FL330. On the opposite end, PSK HIGH (Pulaski, VA) worked the arrivals from the northeast into ATL from FL240-FL330. As ATL grew, both became unworkable. In man's eternal quest to reinvent the wheel, ZTL management decided to spilt the sectors by altitude instead of geographically. The boundaries of SALEM and GA HIGH both looked exactly like PSK and SPA HIGH (respectively) except they only had two altitudes -- FL310 and FL330.

It worked. For awhile. But as they got busier and busier it got harder and harder to work an increasing number of airplanes with only two altitudes. Not surprisingly, all four of these sectors managed to make the "Top Ten" on ZTL's list of operational errors by sector every year. With the introduction of Reduced Vertical Separation Minima (RVSM), SALEM became a piece of cake (comparatively.) It's pretty simple to figure out a sector is easier to work with four altitudes instead of only two.

The introduction of RVSM brought its own set of problems. Every facility had its own idea of how sectors should be spilt by altitude stratum. Some wanted FL240-FL340. Some wanted FL240-FL330. Some wanted something different. I don't remember how it all ended up, I just remember what a mess it was until the dust settled. While it was great progress in the Enroute world, I think it worth noting that it didn't increase the capacity of a single airport. It's still the runways, Stupid.

Don Brown
October 22, 2013

1 comment:

LRod said...

The "super" highs or "ultra" highs, as they were variously called were introduced some time around 1970. When I was at ZJX, ZDC introduced there's from FL330 up. At about the same time, ZTL implemented one at FL350 and up. It wasn't too bad when we didn't have one, because we would monitor both 2100 and 2400 (I think that was the super high code)—obviously long before discrete codes. That way, we (ZJX) could see both strata in both facilities.

Then our traffic got dense enough we had to implement a super high of our own. I think we settled on FL330 and above, which suited the predominant traffic—National flew most of their flights below FL290. But that created headaches with ZTL as our regular highs had to deal with both their regular and super highs, and ZTL's regular highs had to do the same. At a sector like AMG, it was chaos.

When I got to ZAU (1973), they hadn't yet implemented a super high, but it wasn't long before we did. As the overflight component of our operations was so much higher than at ZJX, we started out at FL370 and above. I think, ultimately, we settled on FL350, also probably in the '70s, but by 1976 I had transferred to the terminal area (low altitude), and it wasn't until the great de-specialization of ZAU in the mid '80s that super high affected me.

I have no idea what it would be like to operate with RVSM. To me, FL 310, 350, and 390 are even altitudes (and always will be).

ZJX, ORD, ZAU retired