Investigation Summary
On October 7, 1989, a USAir McDonnell Douglas DC-9-31 was preparing for a scheduled passenger flight to Philadelphia. As the aircraft was being pushed back from the gate, weather conditions deteriorated with moderate to heavy rainfall. During the pushback sequence, a lightning bolt struck the tail of the aircraft. The electrical discharge traveled through the airframe and into the wired interphone system used for communication between the flight deck and the ground crew. The mechanic acting as the ground guide, who was wearing a headset plugged into the aircraft's external jack, received a fatal electrical shock. Investigation revealed that while supervisors and witnesses had monitored the weather and waited for a 15 minute lull in lightning activity before starting the pushback, the airline's own safety procedures mandated a total cessation of ground guide operations during periods of observed lightning. The NTSB cited inadequate weather evaluation and supervision as primary factors in the accident. Per NTSB regulation, these investigations are fact-finding proceedings with no formal issues and no adverse parties, and are not conducted for the purpose of determining the rights or liabilities of any person.
Final Conclusions
The National Transportation Safety Board determined the probable cause to be the inadequate weather evaluation and supervision of the ground guide by company management, the failure of the ground guide to follow established safety procedures, and the prevailing weather conditions (lightning). The NTSB issued its final report on July 29, 1992.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Total hours on type is listed as 180 in the last 90 days; total type hours not specified.
Systems & Failure Modes
Ground Interphone System
A wired communication link allowing ground personnel to speak with the flight crew via a plug-in jack on the aircraft exterior; in this event, it served as a conductive path for the lightning strike.
Interesting Facts
- 01The aircraft sustained no physical damage from the lightning strike.
- 02The airline's safety manual explicitly prohibited ground guide operations during periods of observed lightning.
- 03The ground guide was a mechanic wearing a headset connected directly to the aircraft's communication system.
- 04There were 108 occupants on board (103 passengers and 5 crew members), none of whom were injured; the sole fatality was the ground mechanic.
- 05The weather observation at the time recorded scattered clouds at 2,000 feet and a broken ceiling at 8,000 feet with 2 miles visibility.
Safety Actions & Advisories
Adherence to Ground Safety Manuals
The investigation highlighted the critical importance of adhering to airline safety manuals which prohibit ground operations, specifically those involving wired communication headsets, during periods of observed lightning activity.
Location
NO VERIFIED COORDINATES · Coordinates are the estimate published in the ntsb final report. No map is shown, because a marker here would imply a precision the record does not have.
Reported location: Orlando, Florida, United States