Investigation Summary
Flight 514 was a dedicated training mission for pilots transitioning to the new Boeing 707 jetliner. After performing high-altitude air work to burn off fuel, the crew arrived at the Grumman Aircraft Corporation airfield (Calverton) to practice airport transitions. The crew had successfully completed several maneuvers, including crosswind landings and simulated engine-out approaches. During the final sequence, while on the base leg for Runway 23 at approximately 1,000 to 1,100 feet, the aircraft began a left bank to align with the runway centerline. The bank steepened to 45 degrees before the aircraft suddenly rolled back to the right. The right bank continued until the aircraft was completely inverted. As the nose dropped, the aircraft yawed significantly to the left and continued rolling. Although the crew managed to level the wings just before impact, the aircraft was in a stalled condition with a high sink rate. It struck the ground in a potato field approximately three miles northeast of the airport, followed by a severe kerosene-fed fire.
Final Conclusions
The Civil Aeronautics Board (CAB) determined the probable cause was the crew's failure to recognize and correct the development of excessive yaw, which induced an unintentional rolling maneuver at an altitude insufficient to permit recovery. The investigation highlighted the risks of practicing multi-engine failure maneuvers at low altitudes. As a direct result, the FAA discontinued the requirement for Boeing 707 crews to perform actual landings with 50 percent of power units failed on one side during training and proficiency checks, allowing these maneuvers to be simulated at safer, higher altitudes instead.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Rudder Control System
The early 707 rudder lacked sufficient boost at low speeds; a post-accident modification added boost power to wider ranges of movement to improve control during high-yaw conditions.
Directional Stability
The Boeing 707-120 series exhibited significant yaw-roll coupling, where excessive yaw could rapidly induce a roll that was difficult to counter with ailerons alone at low altitudes.
Interesting Facts
- 01This was the first fatal accident and the first hull loss of a Boeing 707.
- 02The aircraft, named 'Flagship Connecticut', had only 736 total flight hours at the time of the crash.
- 03The aircraft's first flight occurred on May 6, 1959, making it approximately three months old at the time of the accident.
- 04The crash occurred near Brookhaven National Laboratories, a site of secret nuclear research.
- 05The crew was practicing simulated engine-out procedures, a standard training requirement at the time.
- 06The aircraft struck the ground with nearly symmetrical power, indicating the engines were likely responding at the moment of impact.
Safety Actions & Advisories
FAA Training Requirement Change
The FAA discontinued the requirement for actual landings with 50 percent of power units failed on one side during 707 training flights, mandating these be performed at higher altitudes.
Boeing Service Bulletin
On February 5, 1960, Boeing issued a service bulletin for an improved rudder modification to increase control capability at low airspeeds and minimum gross weights.