Brazil's accident investigation agency CENIPA is examining aircraft wreckage at the Gol Linhas Aereas Boeing 737-800 crash site to establish what damage it sustained to lose control so rapidly after its collision on 29 September with an Embraer Legacy.
At present, it is thought the left winglet of the Legacy sliced through the 737-800's hydraulic and electrical lines and compromised the left wing's aileron/spoiler actuators as well as deforming the wing.
Meanwhile, Canada's transportation safety board is downloading information from the data recorders of the two aircraft involved in the 29 September accident. Both the cockpit voice and flight data recorder (CVR/FDR) have been recovered for the ExcelAire Legacy, which survived the impact, but so far only the FDR of the 737 has been found.
Information from air traffic control (ATC) shows the head-on collision occurred at a point at which the Legacy crew planned to be at flight level (FL) 380 (38,000ft/11,580m), but both craft were at FL370 - the planned flight level for the 737. The key problem, according to Brazil's ATC, is that the Legacy was not responding to communications from a point on airway UZ6 only a short distance north west of Brasilia, and its squawk code had been lost, depriving ATC of the ability to monitor the corporate jet's flight level.
International Civil Aviation Organisation procedures for pilots under ATC control by radar, who are aware they have lost communication, is to maintain their current level for a short time and then fly according to their flightplan.
The Legacy's flightplan after departing Sáo José dos Campos was for it to cruise at FL370 on airway UW2 to overhead Brasilia, descend to FL360 on UZ6, changing level to FL380 at TERES, which the Legacy reached before the collision point.
After the collision, the Legacy recovered to the Brazilian air force's Cachimbo airbase, but the wing-damaged 737 went into a high-speed descent and broke up, according to evidence from the distribution of debris. All 148 passengers and six crew in the 737 were killed.
Source: Flight International