The Brazilian Centro de Investigação e Prevenção de Acidentes Aeronáuticos (CENIPA) released their report of the investigation into the mid-air collision between a GOL B737-800 and an Embraer Legacy jet in September 2006. The 737 crashed, killing all 154 on board.
The CENIPA report describes the causal factors in detail. Conslusions were drawn pertaining to the flight crew of the Legacy jet and the air traffic controllers.
The report -amongst others- states the following active failures of the Legacy crew: “lack of an adequate planning of the flight, and insufficient knowledge of the flight plan prepared by the Embraer operator; non-execution of a briefing prior to departure; unintentional change of the transponder setting, failure in prioritizing attention; failure in perceiving that the transponder was not transmitting; delay in recognizing the problem of communication with the air traffic control unit; and non-compliance with the procedures prescribed for communications failure.
On the part of air traffic control the report a.o. states that “By failing to perform the prescribed procedures for the loss of Transponder and radar contact, as well as for communications failure, the ATCO … allowed N600XL to maintain the incorrect flight level (FL370)… Deviations from the procedures regarding the prescribed phraseology were observed, in various situations of the air traffic control activity and in the various control units involved in the accident.”
Commenting the CENIPA report, the NTSB proposes the following probable cause: “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 collision.
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.
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. Further contributing to the accident was inadequate communication between ATC and the N600XL flight crew.” (CENIPA)