Flight Control Configuration
During the approach, the captain disconnected the autopilot but left the autothrottles engaged, employing a "mixed-mode" method of flight control. In this configuration, control of the flight path is mixed between manual and automatic means. The autothrottle began to track an airspeed previously selected in the mode control panel speed window.
Sequence of Events
The captain subsequently disconnected the autothrottles but did not retard the throttles to idle. As a result, automatic speedbrake deployment did not occur during the first touchdown. The aircraft bounced. During the bounce, the captain retarded the thrust levers to idle, causing the speedbrakes to deploy. This led to a loss of lift and a nose-up pitching moment, resulting in a tailstrike.
Manufacturer Recommendations
The airplane manufacturer recommended that autothrottles be used only when the autopilot is engaged. Regarding bounced landing recovery, the manufacturer advised that if the airplane bounces, the pilot should hold or re-establish a normal landing attitude and add thrust as necessary to control the rate of descent. For a "shallow skip or bounce," thrust need not be added; however, for a "high, hard bounce," the pilot should initiate a go-around.
Regulatory Context
Information concerning the dangers of mixed-mode operations and bounced landing recovery was available to the operator and the Federal Aviation Administration (FAA). However, there were no prohibitions on mixed-mode operations, nor were bounced landing recovery guidance required to be listed in any of the operator's FAA-approved manuals. Two months prior to the accident, the Safety Board issued a recommendation to the FAA to require air carriers to incorporate bounced landing recovery techniques in their flight manuals and training. The FAA issued a Safety Alert for Operators (SAFO) recommending that airlines include these techniques, but the SAFO was not mandatory. Consequently, the Safety Board requested the FAA survey air carriers to determine how many had adopted the SAFO. The Safety Board advised the FAA that until the results were known, its recommendation would remain classified as "Open Acceptable Response."