Pilot Journal
Sunday, July 1, 2007

What’s RVSM?

A great idea that allows ATC to fit more airplanes into smaller, radar-less airspace

The problem was simple: too many airplanes and too little sky. This flies in the face of traditional wisdom that suggests it’s a very big sky. While that’s unquestionably true above places such as Chad, Antarctica and the Gobi Desert, there are other places where there’s an uncomfortable amount of aluminum vying for roughly the same airspace. " />

I saw this procedure at work once a few years ago during a return from a Piper Chieftain ferry to Douala, Camaroon, Africa. After the delivery, I hopped on a Sabena Airlines Airbus 330, connected in Brussels to another Sabena 330 flight headed for Boston and was invited up front to the pointy end to ride the jump seat directly behind the captain. We were at FL360 passing south of Iceland when a British Airways 777 (call sign “Speedbird”) came up behind us and was assigned a temporary altitude of 38,000 feet. The BA captain told us this was the first revenue flight of the first British Airways 777.

The Boeing passed almost directly over us, only 2,000 feet above, and the Sabena captain sidestepped his Airbus a few hundred yards to the right and increased power slightly to hold position on the big twinjet. It was truly impressive to look nearly straight up at that beautiful airplane only 2,000 feet away, contrailing huge white streamers of vapor as we flew brief formation seven miles above the ocean. The Sabena captain, a former F-16 pilot, held station just long enough to give his passengers a good look, hoping Iceland Control wouldn’t notice, then reduced power to let Speedbird assume the lead.

In addition to accommodating far more airplanes, adding flight levels 300, 320, 340, 360, 380 and 400 allows qualified aircraft to fly at more-efficient heights and, thereby, save fuel. Airplanes that may be too heavy to climb 4,000 feet under the old rules may be able to manage 2,000 feet. It’s been estimated the fuel savings on North Atlantic routes alone will total $5.3 billion in the first 10 years. RVSM also reduces the need for ATC vectoring, again contributing to fuel savings.

Non-RVSM aircraft can transition through the 29,000- to 41,000-foot block as long as they don’t level off. Above 41,000 feet, airspace returns to the old 2,000 feet of separation.

For their part, flight crews must be educated in the differences between standard and RVSM operation. They need to understand the implications of operating a 200- to 400-ton aluminum tube at closing speeds as great as a mile every four seconds with other traffic only 1,000 vertical feet away.


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