sentences:  The accident was investigated by the Brazilian Air Force's Aeronautical Accidents Investigation and Prevention Center (CENIPA) and the U.S. National Transportation Safety Board (NTSB).In accordance with the provisions of ICAO Annex 13, the NTSB participated in the investigation as representative for the state (country) of manufacture of the Boeing, state of registry and operator of the Embraer, and state of manufacture of the Honeywell avionics equipment installed in both planes.Once the black boxes and communication transcripts were obtained, the investigators interviewed the Legacy jet's flight crew and the air traffic controllers, trying to piece together the scenario which allowed two modern jet aircraft, equipped with the latest anti-collision gear, to collide with each other while on instrument flights in positive control airspace.