2 October 1996, shortly after Aeroperú Boeing 757 took off from Lima at night, it became apparent that two of the most important instruments - the altimeter and the speedometer - were not working.
A few minutes later, 757 hit the surface of the water with its wing and crashed into the Pacific Ocean.
After the wreckage was recovered, it turned out that the reason for the crash was that the Pitot tubes had been sealed with tape (by ground staff, while the aircraft was being cleaned).
