Delta Air Lines Flight 723

Delta Air Lines

Industry	Airline
Founded	May 30, 1924 (1924-05-30)
Headquarters	Atlanta , United States
Products	Passenger air transport
Website	www.delta.com

Delta Air Lines Flight 723 was a domestic passenger service operated by a McDonnell Douglas DC-9 twin-engine jet, flying from Burlington, Vermont to Logan International Airport in Boston, Massachusetts, with an intermediate stop at Manchester, New Hampshire. On July 31, 1973, at 11:08 a.m., while executing an instrument landing system (ILS) approach into Logan under conditions of low cloud cover and fog, the aircraft descended beneath the glidepath, collided with a seawall, and crashed. All 89 individuals on board perished, including one initial survivor who died more than four months later.

Aircraft and crew

The aircraft involved was a DC-9-31 with registration , serial number 47075, built in September 1967 and having logged 14,639 flight hours at the time of the accident. Initially delivered to Northeast Airlines, it became part of Delta Air Lines following their merger in 1972. The cockpit crew consisted of Captain John Streil (49), who had accumulated roughly 14,800 total flight hours including 1,457 on DC-9s since 1970, and First Officer Sidney Burrill (31), possessing nearly 7,000 flight hours with over 200 on the DC-9. A third pilot, Joseph Burrell (52), was present in the jumpseat undergoing DC-9 training but was not yet fully qualified.

Accident sequence

At , Boston approach control vectored the aircraft to intercept the ILS final approach course for runway 4R at a 45-degree angle approximately outside the outer marker. The controller was preoccupied managing a potential conflict between two other planes and did not clear Flight 723 for the approach immediately. The crew requested clearance and received it more than a minute after being vectored to intercept; by this time, the aircraft was high and fast near the outer marker. The flight crew failed to maintain a stabilized descent rate and airspeed, descending below the glideslope while drifting left of the localizer course. The airplane struck a seawall about right of the runway centerline roughly short of the displaced threshold. The impact destroyed the aircraft and resulted in 87 deaths among the 89 people on board. One survivor died within two hours; the other, Leopold Chouinard—a 20-year-old U.S. Air Force sergeant—succumbed to burn injuries on December 11, 1973. Because of regulatory definitions at that time, Chouinard is not officially counted as an NTSB fatality. The definition was revised in 2018 to include fatalities within 30 days post-accident; however, since Chouinard died over four months later, he still would not be classified as such.

Weather conditions at the time included partial fog with a cloud ceiling of , visibility of , light wind conditions, and runway visual range (RVR) measurements between .

Investigation

The National Transportation Safety Board (NTSB) recovered both the cockpit voice recorder (CVR) and flight data recorder (FDR) for detailed examination. Investigators determined that the flight crew likely misapplied the flight director, unintentionally setting it to "go around" mode during final approach instead of selecting the proper approach mode. This mistake contributed to confusion and increased workload, which led to an unstabilized approach deviating from the glide slope. Analysis of the CVR showed no altitude callouts as the aircraft passed below both the glideslope and decision height, ultimately impacting the seawall.

The NTSB’s probable cause statement emphasized:

...the flightcrew’s failure to adequately monitor altitude and recognize passing through decision height during an unstable precision approach amid rapidly changing meteorological conditions. The approach instability originated from excessive airspeed above glide slope at the outer marker and was exacerbated by crew distraction caused by erroneous flight director indications. Additionally, substandard air traffic control procedures contributed to improper aircraft positioning.

See also

• Asiana Airlines Flight 214 – Collided with a seawall after descending beneath the glidepath during landing
• Atlas Air Flight 3591 – Incident triggered by unintentional activation of go-around mode while on approach
• China Airlines Flight 140 – Crash resulting from accidental engagement of go-around mode on final approach
• Air China Flight 129, Garuda Indonesia Flight 152, Air Inter Flight 148, Dan Air Flight 1008 – Additional CFIT incidents associated with errors by air traffic control and flight crews
• List of disasters in Massachusetts by death toll