Investigation Summary
The accident occurred during a period of transition for Delta, which had recently merged with Northeast Airlines. The aircraft, N975NE, had recently undergone a cockpit instrumentation overhaul to standardize it with Delta's fleet. On the day of the accident, the crew was dealing with a rushed schedule due to an unscheduled stop in Manchester to pick up stranded passengers. During the final approach into Boston, the aircraft was positioned poorly by ATC, intercepting the localizer at an excessive speed and altitude. The crew became preoccupied with the flight director, which was likely set in the wrong mode, causing it to provide unreliable guidance. In the thick sea fog, the pilots failed to monitor their actual altitude and descended through the decision height without visual contact, striking the seawall.
Final Conclusions
The NTSB determined the probable cause was the flightcrew's failure to monitor altitude and recognize passage through the decision height during an unstabilized precision approach. Contributing factors included the aircraft passing the outer marker at excessive airspeed and altitude, crew preoccupation with questionable flight director information, and nonstandard air traffic control services that poorly positioned the flight for the final approach.
Photographic Evidence (1)
Video Analysis
How A Passenger Jet Crashed Just Short Of The Runway In Boston | The Crash Of Delta 723 — A detailed look at the events leading to the crash of Delta 723, including the impact of the Northeast Airlines merger and the technical confusion in the cockpit.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
John N. Streil
First Officer
Sidney W. Burrill
Systems & Failure Modes
Flight Director System
The Sperry flight director was likely set to the wrong mode or providing confusing data, distracting the crew from monitoring their raw altimeter data.
Instrument Landing System (ILS)
The crew was attempting a precision approach using the localizer and glide slope, but failed to stabilize the aircraft on the path.
Interesting Facts
- 01The crash remains the deadliest aviation accident in the history of New England.
- 02One passenger, Charles Mealy, requested to deplane in Manchester just before takeoff, narrowly avoiding the disaster.
- 03The aircraft was a former Northeast Airlines jet that had its cockpit instruments modified just months prior to the crash.
- 04The dense sea fog was so thick that air traffic controllers did not see or hear the impact.
- 05The lone survivor, 20-year-old Leopold Chouinard, survived for 133 days after the crash before succumbing to his injuries.
Safety Actions & Advisories
Flight Director Standardization
The NTSB recommended improvements in the standardization of flight director modes and displays to prevent crew confusion during critical phases of flight.
ATC Vectoring Procedures
Recommendations were made to ensure air traffic controllers provide adequate distance for aircraft to intercept the ILS at stabilized speeds and altitudes.