Líneas Aéreas Suramericanas Flight 4246

Investigation

According to the transcript of the voice recorder, the communications agree with the air traffic control information. After the aircraft's last call to Mitú, 48 seconds later a sudden, loud sound is heard, and two seconds later another loud sound is heard. One second later the pilot seems to say "we've been hit"; from that moment exclamations of panic and pain are heard, and 40 seconds later the sound of the stick shaker is heard. Finally, 69 seconds after the first sound, the sound of the final impact is heard. During the descent the co-pilot and the aircraft's technician are heard telling the captain to pull up the aircraft to regain control, which ultimately could not be re-established.

The data produced by the analysis of the flight data recorder show that the flight proceeded normally from take-off to the point where the sounds were heard in the aircraft's cockpit. Although the flight data recorder did not record altitude and speed, by means of the radar data plots and those of the FDR it was possible to establish that the aircraft had a ground speed of 485 knots and was crossing 23,300 feet. This was the last reliable trace shown on the radar and occurred at 16:10:45 local time. The EPR indications were normal throughout the flight, even up to the moment of impact, when they give indications of engines in the reduced position.

The roll indicator before the loss of control indicates a slight rise of the right wing; subsequently the wing dropped slightly and then finally raised the wing progressively more than 80 degrees indicated, with subsequent indeterminate indications. The aircraft's heading began a continuous and progressive shift to the right, which was maintained until slightly before the end of the recording. These indications show that the aircraft lost control completely, falling in a vertical position with clockwise oscillations and vertical accelerations with large negative g-forces, which were also …