Wednesday, December 10, 2008

Brazil Crash Was Primarily Caused by Air Traffic Control Errors, U.S. NTSB Report Finds

The U.S. National Transportation Safety Board issued investigative findings yesterday that concluded simply that the Sept. 29, 2006 mid-air collision that killed 154 over the Amazon was chiefly caused by mistakes by Brazilian air-traffic control that put both aircraft on a collision course at 37,000 feet.

The NTSB report also cites a “loss of effective air-traffic control” as a probable cause of the disaster, as well as “systemic shortcomings” in Brazil’s military-operated air traffic control system.

The report then cites some "contributing" factors in the disaster.

"Contributing to this accident," the NTSB report said, were the "undetected" loss of transponder function on the Legacy caused by "inadvertent deactivation," as well as a breakdown in radio and radar communication between air traffic control and the Legacy on for 50 minutes before the crash.

The NTSB had a team that participated in the lengthy Brazilian military investigation into the crash. The Brazilian military operates air-traffic control in that country, and controllers are military personnel.

The Brazilian report, also issued yesterday, puts far more emphasis on blaming the American pilots and minimizing the air-traffic control errors. The pilots, who are in the U.S., have been criminally charged by Brazil.

The NTSB report describes the “probable cause” of the disaster this way, referring to the Brazilian airliner that went down with all on board as “GOL1907” and to the American Legacy 600 business jet by its tail number, “N600XL” The report refers to Brazilian air-traffic control as “ATC.”:

"The evidence collected during this investigation strongly supports the conclusion that this accident was caused by N600XL and GLO1907 following ATC clearances which directed them to operate in opposite directions on the same airway at the same altitude resulting in a midair."

It adds, “The loss of effective air traffic control was not the result of a single error, but of a combination of numerous individual and institutional ATC factors, which reflected systemic shortcomings in emphasis on positive air-traffic-control concepts."

It adds, "Contributing to this accident was the undetected loss of functionality of the airborne collision-avoidance-system technology as a result of the inadvertent inactivation of the transponder on board N600XL” and “further contributing to the accident was inadequate communication between ATC and the N600XL flight crew."

The report makes a striking contrast to the over 200-page report issued yesterday by the Brazilian Air Force investigative panel, which heavily emphasizes the allegation that the American pilots were largely to blame for the crash.

But the NTSB’s findings state that the Legacy pilots were “not in violation of any regulations” during the flight. Here are some of the findings from the U.S. panel:

---The Brazilian air-traffic controller supervising the flight handed it off "at an unusually early point" as it approached a new sector near Brasilia, losing a routine opportunity for a necessary navigational fix.

---As the Legacy entered the Brasilia sector about an hour before the collision, air-traffic control did not issue an altitude change order for the plane to descend to 36,000 feet for the next leg of the trip over the Amazon.

---Controllers supposedly monitoring the plane in both sectors were "unaware of the statue of N600SL’s altitude clearance" – that is, they did not realize that the Legacy was flying, as cleared, at 37,000 feet -- "and did not take positive action to provide an amended clearance, confirmation or appropriate coordination."

---Technical problems and confusion on the ground caused the controller handling "led to a misunderstanding" in the air-traffic control center at Brasilia about what altitude the Legacy had been cleared at.

---"The collision-avoidance technology aboard [the Legacy] did not function, likely due to an inadvertent deactivation of the transponder …" And "the flight crew of N600XL did not notice" that the transponder was inactive.

---On the ground, "ATC did not take appropriate action in response to the loss" of the Legacy transponder and continued to behave as if the Legacy transponder was operating properly.

---"Neither ATC nor the flight crew recognized the significance of the long time period without two-way communication …" and "ATC did not take adequate action to timely correct a known lost-communication situation with N600XL."

---Air traffic control mistakes in assigning and utilizing radio frequencies and sector-configuration radar "contributed to the breakdown in communication with N600XL and the accident sequence of events."

---The Brazilian military command that runs the air-traffic control system "did not provide adequate training and supervision" for controllers "to appropriately handle this situation."

---Contradicting suggestions in the Brazilian report, the NTSB found that "the evidence does not fully support" Brazilian assertions that inadequate training and flight planning of and by the pilots contributed directly to the accident.

The report by the Brazilian-military-run CENIPA panel -- whose conclusions a Brazilian judge said on Monday were not admissible in a court of law -- goes to great lengths to blame the Americans, while only sketchily conceding that air traffic controllers played a role. Four low-ranking Brazilian air traffic controllers have also been charged criminally in the accident, though the Brazilan Air Force is trying to remove them from civilian court jurisdiction to military jurisdiction.

Joel Weiss, an attorney representing the American pilots, Joe Lepore and Jan Paladino, said today of the Brazilian CENIPA report:

"In counterpoint to the NTSB report, the CENIPA report hides the real and obvious cause of this tragic accident. ATC placed these two competent flight crews on a collision course, traveling toward each other at the same altitude on the same airway. [The Brazilian report] also buries the fact that this was not only a result of major errors by individual air traffic controllers, but of institutional errors built into Brazil’s ATC system. The pilots should not be blamed for a string of utterly catastrophic errors committed by ATC."

A statement issued by ExcelAire, the Long Island charter company that had taken delivery of the new Brazilian-made Legacy 600 in Brazil just hours before it crashed, said it was "unsurprising" that the "heavily slanted" CENIPA report placed "unfair blame on these American pilots."

ExcelAire said, "It is a report by one branch of Brazil’s military, CENIPA, that must deal with catastrophic errors on the part of another branch of Brazil’s military, ATC. It transparently amounts to an attempt to save face in relation to ATC failures that should result in an international black-mark against the safety of Brazil’s ATC system and its skies."

David Rimmer, ExcelAire's executive vice president [and, along with me, one of the five passengers on the Legacy], said: "There is no reliable evidence that the transponder failure was reflected on the Legacy’s cockpit display. On the other hand, an important factor in the accident was the undisputed evidence of the failure of ATC to recognize the transponder failure and to provide increased separation as required by international aviation regulations. If ATC had increased aircraft separation as required, the accident would have been avoided."

I'll link to the Brazilian report as soon as I get a translation.


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