Voice recorders from two jets that collided over Germany show a Swiss air traffic controller's order for a Russian pilot to descend contradicted the cockpit warning system command.
The voice recorders indicate the automatic cockpit warning systems issued simultaneous instructions for the Russian jet to climb and a cargo jet to descend about 45 seconds before they collided.
But one second after the on-board system warnings, the Zurich tower, which was in charge of directing the planes, told the Russian plane to descend, German investigators said, citing voice recorders from both planes recovered at the crash site.
The Russian pilot did not immediately respond to the tower's command, and the Swiss air controllers repeated the order 14 seconds later, the voice recorders indicate.
The Russian pilot responded, and 30 seconds later the planes crashed at 35,000 feet.
German investigators did not release a transcript of the voice recorders, or further details of any exchanges.
PA
