Tuesday, November 27, 2007

The Legacy Transponder: Case Closed?

The Brazilian Air Force panel still investigating the Sept. 29, 2006 mid-air collision over the Amazon between a Gol 737 and a U.S.-owned Legacy business jet, in which 154 died, has issued a startling conclusion.

There are no indications that the Legacy's transponder was accidentally turned off with an unintentional slip of a pilot's toe off a badly designed footrest in the cockpit, or by one of the Legacy's pilots inadvertently jostling the device with his laptop.

There is, furthermore, no assertion, at least by anyone who isn't a delusional anti-American wack-job, that the pilots deliberately turned off the transponder, which would have been an act of sheer insanity on their part.

(Early on, the excitable former defense minister, Wonderful Waldir Pires, did of course assert just that. Someone showed him a picture of a wildly oscillating reading on a malfunctioning radar screen, which persuaded the poor old gentleman that the Americans obviously turned off the transponder so they could perform undetected aerial loop-d-loops in the Amazonian skies, evidently to "show off" the new airplane to the reporter on board, me -- though that inattentive reporter subsequently and inexplicably (unless he was part of the loop-d-loop coverup conspiracy!) failed to make note of said loop-d-loops in his stories about the crash. Wonderful Waldir has since departed for a much-needed retirement rest to coddle his loop-d-loops in peace.)

Anyway, I direct you once again to a detailed report filed last November by Excelaire, the owner of the Legacy, which argues that the Legacy's transponder had a history of problems and was not "factory fresh" before it was installed in the new Legacy. The .pdf of the report doesn't have page numbers, but the pertinent part is Section 6, titled "Production and Pre-Delivery Problems ..."

Neither Honeywell, the manufacturer of the transponder, nor Embraer, the Brazilian manufacturer of the Legacy, has disputed that report, although neither has addressed it publicly, to my knowledge.

But the Air Force investigation moves us inexorably closer to the conclusion, argued here for over a year, that the collision occurred as a result of a series of things that went terribly wrong, starting with the fact that Brazilian air traffic control, understaffed and saddled with malfunctioning technology, made grave mistakes that put both aircraft on a fatal collision course at 37,000 feet that afternoon.

The transponder issue, and the American pilots' role in it, was secondary: A working transponder, with its tie-in to an aircraft anti-collision alarm, would have been the last safeguard that might (emphasize might) have prevented a collision that was already well set in motion through a series of errors and malfunctions on the ground.

Of course, the history of this sad case has shown that some authorities in Brazil, having made the grave mistake of rushing to criminalize this accident even before the bodies were brought out of the jungle, are absolutely determined to somehow pin blame on the Americans. Don't forget, the basic criminal charge against them is "failing to ensure the safety of Brazilian skies." That covers a whole lotta sky.

The two American pilots are still on trial, in absentia, on those criminal charges, which also stipulate that they were involuntarily responsible for whatever role in the accident they might be found guilty of.

Still, a guilty verdict carries prison sentences. Though the U.S. does not have an extradition agreement on a conviction on unintentional homicide, the pilots, if found guilty, would be considered international fugitives in many countries that do have applicable treaties with Brazil. For a pilot -- one of them still flies internationally -- that could lead to real trouble.

The Brazilian authorities have not yet addressed rampant safety problems in the operation of their military-run air traffic control system.

But as to the American pilots, who have been scapegoated in this tragedy since the day the seven of us fell from the sky onto that forlorn Amazon air strip: If the transponder failed because of manufacturing problems, I have only two words to say:

Case Closed.

Here is the text of the Air Force report, as translated by Richard Pedicini in Sao Paulo:

Flight 1907 – Commission clarifies on transponder

Because of the release of information, on the part of organs of the domestic and international press, on the accidental interruption of transponder transmissions in the case of the Flight 1907 accident, which provoked the non-functioning of the anti-collision system, the Aeronautic Accident Commission of Investigation informs that:

1) Up to now, there are no indications that there occurred an intentional act on the part of the crew of aircraft prefix NX600L in the sense of interrupting the transponder's transmission (STAND BY mode) ;

2) Ergonometic studies, CVR (Cockpit Voice Recorder) data, and reconstructions demonstrate that:

- The interruption of transponder transmissions occurred during a period of silence in the cabin, lasting 1 minute and 43 seconds, while the pilots of aircraft NX600L performed flight planning calculations for the next stage of the trip, with the pilot on the right using a laptop;

- According to the report of the reenactment flight, there is no way that a laptop resting on the lap of the pilot on the right can touch the button on the RMU (Radio Management Unit) control screen twice, in less than 20 seconds, to put the transponder in STAND BY mode;

- There is no way to utilize the footrest during the flight with the seat in the normal piiloting position. It would be necessary to move it back. The movements of the seat positions are registered on the CVR and there is no register of movement (cabin noise) during the period in which the transponder ceases operation;

- The footrests have a protection which impedes a shoe sole from directly contacting the panel;

- If this occurs by an action by the pilot on the left, flexing and contorting his right foot, the buttons reached would be the first two, from top to bottom and on the left side of the RMU control panel, which have as their function the changing of the radio frequencies, and not the fourth button, which would permit changing the transponder mode (if it were touched twice in succession, in an interval of less than 20 seconds);

- Only the pilot on the left can, observing the description in the previous item, place his foot on the left side of the RMU);

- On the CVR, there is a commentary by the pilot on the left recommending not putting feet up in the cabin during the flight.

From all the evidence presented, the Commission reiterates that the conclusions aired by some organizations and press organs, domestic and international, on the use of the laptop or of the "footrest" on the flight in question, do not have any technical support in the work of the Aeronautic Accident Commission of Investigation, which is responsible for the procedure aimed at prevention.

Source: Aeronautic Accident Commission of Investigation / CENIPA



AeroObserver said...

I'm curious to know more about the laptop: did it have Wi-Fi and, if so, was it turned on? Can a Wi-Fi signal transmission so close to the transponder cause the transponder to fail without the pilots knowing it? Also, was the copilot using the laptop immediately before the collision?

Mr. Peshak said...

There is still an unexplored explanation. 45th Annual Air Traffic Control Association Proceedings, Fall 2000, Library of Congress Control Card Number 79-643160, ISSN 0192-8740, pages 1-5.

How much you wanna bet that the FAA, the avionics manufacturer, both airplane manufacturers don't want this investigated?

Here is what happened to one such investigator, an ATC that ran two airplanes into eachother (they missed) because one was NOT on his scope (sound familiar?):