US National Transportation Safety Board, commenting on the Brazilian Air Force's final report issued last week on the Sep. 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, emphasized that ATC failures were the primary cause of the accident.

While not rejecting the report's conclusion that the ExcelAire pilots inadvertently turned off the Legacy's transponder, the board emphatically laid blame on Brazilian ATC, arguing its core responsibility is to ensure aircraft do not collide. "Only the ATC system had knowledge of both airplanes and their respective intentions," NTSB stated.

The Legacy's transponder was off and did not send any information to ATC for 58 min., a finding in the Air Force report that NTSB does not dispute. But whereas the report cited pilot negligence as a probable cause, NTSB was sharply critical of ATC, which "had many opportunities to realize that [the Legacy] was not in two-way communication."

It added, "The flight crew would not have any knowledge of radio transceiver locations and coverage, but ATC does. [The controller with responsibility] never attempted to try a relay through other flight crews, emergency frequency, or any other means ... ATC clearly had knowledge that the crew was not in communication well in advance of the crew, yet ATC did not take sufficient action." NTSB further described poor communication between controllers and cited their failure to adhere to "basic ATC concepts."

The Brazilian report detailed the Legacy's flight deck operations and also alleged that the two American pilots were unfamiliar with Brazilian air traffic regulations. While the Brazilian version also cited ATC mistakes, NTSB countered that ATC safety issues are not just one of several causes of the accident.

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." It added that the ExcelAire flight crew was "not in violation of any regulations."