Low and high intensity alarm signals can be heard on recovered recordings from the plane, along with the sounds of repeated banging on the cockpit door, he said. The investigation report does not say who was banging, but Abreu asserted that the co-pilot was not in the cockpit at the time of the crash and not responsible for the crash. The “black box” flight recorders were recovered intact and sent to the United States National Transport Safety Board in Washington to be decoded and transcribed.
Other indicators show manual operations were used, he said, adding that “all these operations required detailed knowledge of the plane’s controls, and showed a clear intention to crash the aircraft.”
The control tower had lost voice and radar contact and set search operations in motion. The wreckage of the plane was found in the following days.