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The dangers of precision air travel

William Langewiesche wrote a long piece for the January 2009 issue of Vanity Fair about the September 2006 collision of a Legacy 600 private jet and Gol Flight 1907 over the Amazon basin in Brazil. It is a tale of “a paradox associated with progress and modern times”.

Navigational precision poses dangers not immediately apparent. In the Legacy, it was based on three systems. The first was an ultra-accurate altimeter, capable of measuring the atmosphere with such finesse that at Flight Level 370 it could distinguish the Legacy’s altitude within perhaps five feet. The second was almost as accurate. It was the airplane’s satellite-based G.P.S. receiver, a positioning system that kept track of the airplane’s geographic location within a distance of half of its wingspan, and that, linked to a navigational database, defined the assigned airway with equal precision. The third was an autopilot that flew better than its human masters, and, however mindlessly, worked with the altimeter and G.P.S. to keep the airplane spot-on. Such capability is relatively new. Until recently, head-on airplanes mistakenly assigned the same altitude and route by Air Traffic Control would almost certainly have passed some distance apart, due to the navigation slop inherent in their systems. But this is no longer true. The problem for the Legacy was that the Boeing coming at them on the same assigned flight path had equipment that was every bit as precise.

Interesting throughout, it becomes downright gripping about 2/3rds of the way through. The interplay between and the eventual reversal of the pilot and co-pilot of the Legacy is fascinating.

Update: Joe Sharkey, who was on the Legacy jet when it collided with the 737, doesn’t like Langewiesche’s article very much, calling it a “journalistically disgraceful article”.

I’m not a pilot but my dad was and I flew all the time with him when I was a kid. I know what Sharkey is talking about when he says that flying a plane is not like driving a car; once you get in the air and are pointed in the right direction with the autopilot on, there’s not a whole lot the pilot is required to do. But in my reading of the article, I don’t think Langewiesche was saying that the two Legacy pilots in particular were screwing around or negligent. They were acting pretty much how any other two pilots in the same situation might act. Langewiesche’s point seems to be: the experience of flying a plane like the Legacy, with all the technology that’s there to help pilots โ€” good and bad โ€” do their jobs, might actually be made worse and more dangerous by that technology. Also that, as he stated at the beginning of the article, there were a whole lot of different decisions and non-decisions that converged to make that event happen…a huge pile of bad luck.

As for not talking to any of the people on the Legacy for the article, I don’t think that’s as significant as Sharkey asserts. Everyone who was aboard the Legacy jet that day is likely feeling pretty defensive about the whole thing given the intense reaction against them by the Brazilian government, the pilots doubly so given that they’re involved in a lawsuit. A prudent journalist would rightly be worried about the veracity of a narrative offered up in these circumstances, almost two years after the fact. Instead, Langewiesche chose to rely not on opinions and recollections but on the available data โ€” the cockpit voice recordings, air traffic control records, etc….how people actually behaved in the situation, not how they say they acted or what they thought about it. Put it this way: if Sharkey and Langewiesche were to write competing books about the collision, the former based on extensive interviews with those involved and the latter based only on the available evidence, neither would be much closer to “the truth” than the other. (thx, scott)