The first explanation is that the lack of vertical control caused by the broken elevator torque tube stalled the aircraft . Because of the lack of pitch control, it would have been easy for the aircraft to fall back into a stall repeatedly, each time losing altitude.
32.
The resulting datum surface, with minor modifications in two metropolitan areas, has been termed the Australian Height Datum ( AHD ) and was adopted by the National Mapping Council as the datum to which all vertical control for mapping ( and other surveying functions ) is to be referred ."
33.
Twelve minutes before the crash of the plane, an MD-83 on a flight from Puerto Vallarta, Mexico, to San Francisco, with 88 people aboard, and long after the crew realized that there was a problem with the horizontal control system, the plane " experienced an apparent loss of vertical control, " said John Hammerschmidt, the safety board member assigned to this crash.
