Investigation Summary
The accident occurred at night under clear visibility. The Cessna 441, operated by Superior Aviation, had recently arrived and was instructed by ground control to 'back-taxi into position' and hold on Runway 31. However, the pilot failed to repeat the runway assignment and instead taxied onto Runway 30R, the same runway assigned to TWA Flight 427. The MD-82 was cleared for takeoff and had accelerated to approximately 80 knots when the crew spotted the Cessna stationary on the runway. The MD-82 captain applied hard left rudder and maximum braking, which investigators later determined prevented a direct center-line impact that would have likely resulted in much higher fatalities. The MD-82's right wing sliced through the Cessna's tail and cockpit area. Despite a significant fuel spill from the MD-82's damaged wing, no fire broke out. The NTSB investigation highlighted that the Cessna pilot likely had a 'preconceived notion' that he would depart from Runway 30R because he had used it for landing minutes earlier.
Final Conclusions
The NTSB determined the probable cause was the Cessna 441 pilot's mistaken belief that his assigned departure runway was 30R, leading to an undetected runway incursion. Contributing factors included the lack of ATIS information regarding the use of Runway 31 for departures and the ground controller's use of non-standard phrasing ('back-taxi'). The NTSB also noted that the absence of Airport Surface Detection Equipment (ASDE-3) prevented controllers from visually detecting the Cessna's incorrect position in the dark.
Video Analysis
The St. Louis Runway Collision | TWA Flight 427 — A detailed look at the 1994 runway collision between a TWA MD-82 and a Cessna 441, examining the pilot errors and air traffic control factors that led to the disaster.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Trans World Airlines TWA 427 — McDonnell Douglas MD-82 · N954U
Superior Aviation N441KM — Cessna 441 Conquest II · N441KM
Systems & Failure Modes
ASDE-3 / AMASS
Ground radar systems designed to detect aircraft positions on the airfield; St. Louis lacked this equipment at the time, which would have alerted controllers to the Cessna's incorrect position.
ATIS
Automatic Terminal Information Service; the broadcast failed to mention Runway 31 was in use, which investigators believe contributed to the Cessna pilot's confusion.
Interesting Facts
- 01The MD-82 crew's evasive left-turn maneuver was credited with preventing a more catastrophic collision.
- 02The Cessna pilot did not read back the runway assignment, and the controller did not request a readback.
- 03Runway 31 was not listed as an active runway on the ATIS broadcast at the time of the accident.
- 04The MD-82 (N954U) was repaired and returned to service, eventually flying for American Airlines.
- 05The airport remained open during the evacuation, with aircraft landing on the parallel runway 30L.
Safety Actions & Advisories
Runway Readback Requirement
The FAA modified the air traffic controller's handbook to mandate that controllers obtain a verbal confirmation of runway assignments from pilots.
Standardized Terminology
The NTSB recommended formalizing the definition of 'back-taxi' to ensure standardized use and understanding among pilots and controllers.
Ground Radar Installation
The NTSB recommended the immediate installation of ground radar (ASDE) at major airports like St. Louis to prevent undetected runway incursions.
Post-Incident Airport Closure
The NTSB reiterated a standing recommendation that airports should immediately close following any incident until the situation has been fully assessed.