Investigation Summary
Flight 250 was operating a multi-leg route from New Orleans to Minneapolis. Upon departing Kansas City for Omaha, the crew was aware of a line of thunderstorms. While the crew requested to fly at 5,000 feet to stay below the worst of the weather, this altitude was also influenced by Air Traffic Control requirements for traffic separation, as other aircraft occupied the higher flight levels. As they approached the squall line, the aircraft encountered a violent updraft. The investigation revealed that the right tailplane and vertical stabilizer failed essentially simultaneously due to the extreme aerodynamic loads exacerbated by pilot rudder inputs during the turbulence. The loss of the tail caused the aircraft to pitch violently nose down, leading to the negative-load failure of the right wing within one to two seconds. The wreckage was scattered over a mile, confirming a high-altitude breakup. This accident was notable for being the first U.S. investigation to successfully utilize a Cockpit Voice Recorder (CVR) to reconstruct the final moments. While the Flight Data Recorder (FDR) was destroyed, investigators used the CVR's background noise to estimate changes in speed and altitude.
Final Conclusions
The Civil Aeronautics Board (CAB) determined the probable cause was in-flight structural failure caused by extreme turbulence during operation of the aircraft in an area of avoidable hazardous weather. A contributing factor was the application of rudder to an extent that resultant loads exceeded the ultimate strength of the vertical fin and tailplane, possibly due to the pilot's lack of 'feel force' from the simulators during the upset. Although the CAB conducted the original investigation, the National Transportation Safety Board (NTSB), established in 1967, maintains the official record of these findings.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Donald Pauly, age 47.
First Officer
James Hilliker, age 39.
Systems & Failure Modes
Vertical Stabilizer
The tail fin failed structurally when the aircraft encountered extreme turbulence and sudden rudder deflection.
Cockpit Voice Recorder (CVR)
Used to estimate speed and altitude changes via background noise analysis after the FDR was destroyed.
Rudder Feel Simulator
The investigation suggested a lack of 'feel force' may have led the pilot to apply excessive rudder pressure.
Interesting Facts
- 01This was the first fatal crash of a BAC 1-11 in the United States.
- 02It was the first U.S. accident investigation to use Cockpit Voice Recorder (CVR) data to aid the findings.
- 03The aircraft was nearly new, with only 2,307 total flight hours at the time of the crash.
- 04Renowned meteorologist Dr. Ted Fujita was hired by the manufacturer to study the weather's impact on the jet.
- 05Braniff dispatchers knew other flights had diverted or delayed due to the storm but did not relay this specific information to Flight 250.
Safety Actions & Advisories
Weather Dispatch Improvements
The accident highlighted the need for better communication between dispatchers and crews regarding the real-time movements and diversions of other aircraft in the fleet due to weather.
CVR Implementation
The successful use of the CVR in this investigation proved the device's value, leading to more rigorous standards for flight recorder survivability and usage.