Investigation Summary
The accident occurred during a proficiency check for three TWA line captains. The instructor pilot (IP) had simulated a failure of the No. 4 engine by retarding its throttle to idle. During the subsequent three-engine ILS approach to Runway 13, a hydraulic pressure line to the left outboard spoiler actuator failed due to metal fatigue. This failure caused a rapid overboard leak of the utility hydraulic system fluid. When the IP called for a missed approach at the decision height, the crew found they could not retract the flaps from the 50 degree position or retract the landing gear because the hydraulic system was depleted. Approximately 16 to 18 seconds into the go-around, the crew observed the zero fluid level. The captain commanded the hydraulic pumps to be shut off, which was the first item on the emergency checklist. However, the full emergency checklist was not called for or followed. This action was catastrophic in the current flight configuration: the Boeing 707 required hydraulic power for the rudder actuator to maintain control at low speeds with asymmetric thrust. The minimum control speed (Vmca) without rudder power was 180 knots, but the aircraft was only traveling at approximately 130 knots. The resulting loss of directional control caused the aircraft to veer right and crash.
Final Conclusions
The NTSB determined the probable cause was a loss of directional control resulting from the intentional shutdown of hydraulic pumps without concurrently restoring power to the simulated failed engine. The investigation highlighted that the hydraulic fluid loss emergency procedure was inadequate when applied to the specific operating configuration of the aircraft (low speed, high drag, and asymmetric thrust). The initial mechanical trigger was a fatigue failure in a flareless coupling sleeve of the left outboard spoiler actuator downline.
Video Analysis
The Training Flight From Hell | The Crash Of TWA 5787 — A detailed look at the 1969 crash of TWA Flight 5787, where a routine training maneuver turned fatal due to a mechanical failure and procedural complications.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Instructor Pilot
Captain Donald Sklarin (Instructor Pilot)
Captain
Captain Harry D. Gaines (Trainee)
Flight Engineer
Second Officer Frank J. Jonke
Observer Pilot
Captain John D. North
Observer Pilot
Captain Robert H. Schramm
Systems & Failure Modes
Utility Hydraulic System
Powered the landing gear, flaps, and spoilers; a leak in the spoiler actuator line drained the entire system.
Rudder Hydraulic Boost
Provides the necessary force to move the rudder at low speeds; shutting off the pumps disabled this boost, making the rudder ineffective against asymmetric thrust.
Flight Data Recorder
A Lockhart 109CR recorder was recovered, providing altitude, heading, and airspeed data for the final 2 minutes and 45 seconds.
Interesting Facts
- 01The aircraft was a Boeing 707-331C 'Cargojet' that had just completed a flight from Frankfurt earlier that day.
- 02The minimum control speed (Vmca) without rudder power for this aircraft was 180 knots, significantly higher than the 130 knots maintained during the go-around.
- 03The hydraulic failure was caused by a fatigue crack in a stainless steel hydraulic line at a flareless coupling.
- 04All five crew members on board were TWA captains or officers; there were no passengers.
- 05The NTSB report noted that the crew did not restore power to the No. 4 engine, which would have eliminated the asymmetric thrust condition.
Safety Actions & Advisories
Checklist Revision
Source ↗TWA and the FAA reviewed and amended procedures for hydraulic failure and simulated engine failures to ensure rudder power requirements are considered.
NTSB Recommendation A-70-011
Source ↗The NTSB recommended that the FAA require all Boeing 707/720 flight manuals to include a warning that the hydraulic fluid loss checklist must not be followed until the aircraft is in a safe flight configuration (flaps retracted and symmetric thrust restored).