At 3:51 pm, an air traffic controller in the Brasilia ACC (CINDACTA 1) instructed N600XL to change frequencies to the next controller's sector. The crew of N600XL reported in on the assigned frequency that the flight was level at FL370. ATC acknowledged and instructed the crew to "ident"
(flash their transponder). Radar indicates that the ident was observed.
This was the last two-way communication between N600XL and ATC. At this time the airplane was approximately 40 nautical miles south of BRS.
At 3:56pm the Legacy N600XL passed BRS level at FL370. There is no record of a request from N600XL to the control agencies to conduct a change of altitude, after reaching flight level 370. The crew
made calls, but there is no communication in which they requested a change of flight level. There is also no record of any instruction from air traffic controllers at Brasilia Center to the aircraft, directing a change of altitude.
When the airplane was about 30 miles north-northwest of BRS, at 4:02 pm, the transponder of N600XL was no longer being received by ATC radar. A transponder reports a unique code, aiding radar
identification, and provides an accurate indication of the airplane's altitude. Additionally, the transponder is a required component for the operation of Traffic Collision Avoidance System equipment, commonly called the TCAS system.
Between 3:51 pm and 4:26 pm, there were no attempts to establish radio communications from either the crew of N600XL or ATC. At 4:26 pm the CINDACTA 1 controller made a "blind call" to N600XL. Subsequently until 4:53 pm, the controller made an additional 6 radio calls attempting to establish contact. The 4:53 call instructed the crew to change to frequencies 123.32 or 126.45. No replies were received.
There is no indication that the crew of N600XL performed any abnormal maneuvers during the flight. Flight Data Recorder information indicates that the airplane was level at FL370, on course along UZ6, and at a steady speed, until the collision. Primary (non-transponder) radar returns were received corresponding to the estimated position of N600XL until about 4:30 pm. For 2 minutes, no returns were received, then returns reappeared until 4:38 pm. After that time, radar returns were
sporadic.
Beginning at 4:48 pm, the crew of N600XL made a series of 12 radio calls to ATC attempting to make contact. At 4:53, the crew heard the call instructing them to change frequencies, but the pilot did
not understand all of the digits, and requested a repeat. No reply from ATC was received. The pilot made 7 more attempts to establish contact.
At 4:56:54 pm the collision occurred at FL370, at a point about 460 nautical miles north-northwest of BRS, on airway UZ6.