Delta Air Lines Flight 723

Delta Air Lines Flight 723 was a scheduled domestic passenger flight operated by a McDonnell Douglas DC-9 twin-engine jetliner, from Burlington, Vermont, to Logan International Airport in Boston, Massachusetts, with an intermediate stop in Manchester, New Hampshire. On July 31, 1973, at 11:08 a.m., while on an instrument landing system (ILS) instrument approach into Logan in low clouds and fog, the aircraft descended below the glidepath, struck a seawall, and crashed. All 89 of the occupants aboard were killed, including an initial survivor who died months after the crash—in the official report, that person was listed as a survivor with critical injuries, due to length of time between the accident and when he died.

Accident sequence

The aircraft, flying at 3000 ft, had been vectored by Boston's approach control to intercept the final approach course to the ILS runway 4R approach at a 45-degree angle, about 2 nmi outside the outer marker. The weather conditions at the time of the crash were partial obscuration and fog, with a ceiling of 400 ft, 1/2 mile visibility, and light winds. Runway visual range (RVR) was 1400 to 6000 ft.

It was later revealed that the controller was busy handling a potential collision conflict between two other aircraft, and therefore neglected to clear Flight 723 for the approach. The flight crew had to ask the controller for approach clearance, which was immediately given, but by that time—more than a minute after the intercept vector had been issued—they were high and fast and almost over the outer marker. The flight crew subsequently failed to stabilize the aircraft's descent rate and airspeed, descended below the glideslope and drifted left of the localizer course, hitting a seawall about 165 ft to the right of the extended runway centerline, about 3000 ft short of the runway's displaced threshold.

The aircraft was destroyed and 87 of its 89 occupants were dead when rescuers arrived. One of the two initial survivors died after two hours, and the other was Leopold Chouinard, a 20-year-old sergeant in the U.S. Air Force, who died of burn injuries on December 11, 1973. Chouinard is not listed by the National Transportation Safety Board (NTSB) as an official Delta 723 fatality due to requirements in the Code of Federal Regulations which, in 1973, defined a crash fatality as taking place within seven days of an accident. The rule was subsequently changed in 2018, such that death must occur within 30 days of a crash. Even under the revised rule, Chouinard would not be listed, as he died more than four months after the accident.