AMG High

Elsewhere I referred obliquely to the NOSE rule of altitude assignment—North Odd, South Even. It’s pretty much an East Coast rule, and in truth it’s just a reapplication of a more significant, but unpronouncable rule, East Odd, West Even— EOWE. In other words, Eastbound flights fly at odd altitudes and westbound flights fly at even altitudes. Of course it’s dead simple to apply that nowadays with RVSM (reduced vertical separation minima), but back in the stone age we had to apply 2,000 feet separation above FL290, so FL310, FL350, FL390, and FL430 were all “even” altitudes to us. Controllers hired on since about 2004 will have no understanding of how to think like that, whatsoever.

Anyway, while that’s something of an interesting sidebar, it doesn’t change the AMG High story that I’m trying to tell. The real groundwork for understanding the story has to do with traffic patterns between various aviation markets. Most of it is simple—LAX-ORD is east-west, as is SFO-ATL. MIA-JFK is north-south, as is FLL-BUF. And that’s generally fine—except when flights going MIA to ORD start out flying up the east coast instead of directly toward ATL. Similarly, flights from DTW to TPA might come down over TYS to AGS and then over AMG. In fact, the “over AMG” part was a common point in all of those types of flights.

Here was the problem (and for the purposes of this discussion all aircraft are at FL330—the most popular altitude at the time): when a flight was coming over ATL to PBI via JAX, the majority of the flight was at an odd altitude. Hold that thought. When a flight was coming from over JAX to ATL, the initial segment, if not majority, of the flight was at an odd altitude. As soon as the northbound made the turn at JAX (or the southeastbound approached JAX), he was head on at the same altitude as the other. No good. Moreover, at some point the southeastbound flight had to change to an even altitude for ZMA and similarly, the northwestbound flight had to change to an even altitude for ZTL. Trust me this is the Cliff’s Notes version of what was wrong with AMG High. A very high percentage of flights that transited the sector had to be moved—either to meet a right-altitude-for-direction-of-flight dictum in a succeeding sector, or to save their lives.

And you thought ATC was “cleared to land” or “cleared for takeoff.” We used to say there were five airways converging at AMG (J45 to and from, J85 to and from, plus J75), and an airplane could be on each one of them heading for AMG, all at the same altitude, and all be at the right altitude for direction of flight. It made for some harrowing times. I worked AMG frequently before the high altitude split, then never worked it again. I can’t say I missed it.

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Last updated: 20 January 2011