Tuesday, December 23, 2008

Brazil Crash: Finally, Someone Gets It Right

In all of the stories updating the Brazil mid-air collision, almost no one in the media has really got it right.

This includes one William Langewiesche, in a journalistically disgraceful article in the current Vanity Fair, in which the evidently clairvoyant Langewiesche narrates a fatuous description of the scene on the Legacy jet -- without having had the courage to contact any of us who were actually on the plane for our observations on his suppositions.

More on that later.

Anyway, I am impressed by an article this week in Air Transport World magazine. The writer, Aaron Karp, gets it exactly right in his update on the shaky Brazilian air force report on the crash. Here's his report:


Assessing blame: Gol 737 crash report cites ExcelAire pilots, but experts finger ATC

December 22, 2008--The final report released earlier this month on the Sept. 29, 2006, midair collision between a Gol 737-800 and an ExcelAire Legacy 600 that led to the deaths of all 154 aboard the 737 has cast a sharp focus on ATC organizations' critical responsibilities in managing traffic as well as the problematic role politics can play in accident investigations.

Brazil's Centro de Investigacao e Prevencao de Acidentes Aeronauticos (CENIPA), a division of the country's Air Force, issued a report widely praised for its attention to detail and its willingness to spotlight weaknesses in the Air Force-controlled ATC system. But the decision by CENIPA to cite negligence by the ExcelAire pilots as a probable cause left aviation safety experts scratching their heads (ATWOnline, Dec. 11). While there is little dispute that the ExcelAire pilots inadvertently turned off the Legacy's transponder, causing no information on the aircraft's position to be sent to ATC for 58 min., the "primary responsibility" for the accident clearly rests with ATC, Flight Safety Foundation President and CEO William Voss tells ATWOnline.

Voss has particular expertise in ATC, having served previously as director of ICAO's Air Navigation Bureau and director of air traffic systems development at US FAA. "Radio failures and transponder failures are the kind of things that ATC expects to deal with," he explains. "They're routine and should have nothing to do with whether aircraft remain separated ... [When a transponder fails], there is a long list of things that has to be done by the ATC unit." As the US National Transportation Safety Board stated in its response to the Brazilian report, the controller with responsibility "never attempted to try a relay through other flight crews, emergency frequency, or any other means" to communicate with the Legacy.

Beyond trying alternate means to contact the ExcelAire pilots, controllers also assumed that the aircraft remained at the same altitude where it was when the transponder went off and directed the 737 accordingly, a major mistake, according to Voss. "A controller has an absolute obligation not to assume that an aircraft is at an altitude, but has an obligation to prove where the aircraft is," he says. "There has to be clear proof. . .What should be done if you can't prove [the aircraft's position] is you go to the aircraft you're talking to [the 737] and turn him." ATC assumed the Legacy was flying at 36,000 ft. when it was actually at 37,000 ft., the same altitude as the 737.

One of the reasons there does not appear to have been the necessary urgency when the Legacy lost contact is that ATC communication over the Amazon is known to be spotty. "On both sides of the microphone [pilots and controllers], there was never a sense that this was an ATC communication failure," Voss explains. "Everyone expected communication to be intermittent."

Another factor, one that certainly can serve as a lesson going forward, is the difference in how US and non-US pilots respond to ATC communication lapses. In the US, pilots are instructed that ATC's last assigned altitude overrides the flight plan. Outside the US, international norms call for pilots to revert to the flight plan since ATC communications may have been misunderstood, particularly when borders are being crossed. So controllers outside the US may think that the pilots would "fall back on the flight plan, which is absolutely counterintuitive to a pilot raised in a US environment," Voss says, adding that US pilots who fly internationally should be instructed on this "difference in philosophy."

This may be what CENIPA was getting at when it alleged that the two Americans piloting the Legacy were unfamiliar with Brazilian air traffic regulations. Nevertheless, all issues related to the crash "stem from the basic investigative question, namely, how the primary mission of ATC to separate aircraft within positive controlled airspace was unsuccessful," stated NTSB, adding that the pilots were "not in violation of any regulations." Preliminary reports found that the pilots attempted to contact ATC 19 times in the 8 min. prior to the crash without success.

The rush in Brazil to blame the surviving ExcelAire pilots was severe in the immediate aftermath of the accident. The pilots were detained in Brazil for more than two months after the crash amid a heated political atmosphere, and Brazilian police in late 2006 charged them with endangering aircraft safety. Brazilian officials were criticized heavily for "criminalizing" the accident investigation and, while the final report goes further in citing ATC errors than many expected, political considerations may have contributed to its tone, which seems to place equal blame on the Legacy pilots.

"The takeaway from this is that politics and aviation safety mix very badly," Voss says. "This [accident] caused a significant political uproar in Brazil and some of the comments made by officials [in the crash's aftermath] had significant political overtones, and political pressure was brought to bear in the investigation. . .Very political, knee-jerk reactions should not be playing a role in accident investigations."

--Aaron Karp


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