Incident Overview
An air carrier transport airplane experienced an abrupt maneuver during its initial descent sequence. The flight crew had received clearance to descend from flight level 390 (FL390) to flight level 330 (FL330). The captain initiated the descent while the first officer began programming the flight management system (FMS).
Flight Crew Actions
According to the first officer, the airplane had passed FL330 when the first officer looked up and queried the captain. The captain then immediately arrested the descent and leveled off at FL330. The captain later reported to passengers that the maneuver was due to turbulence. The fasten seat belt sign had been illuminated, but no crew member recalled any accompanying announcement.
Passenger and Cabin Crew Reports
All flight attendants stated that the flight was smooth prior to the event. They, along with an injured passenger who was in the lavatory at the time, described being pushed downward during the occurrence. The passenger injury resulted from the event.
Investigation Details
The Safety Board was not notified of the accident until almost one year after the event. Consequently, flight data recorders, cockpit voice recorders, and air traffic control recordings were not available for review.