Date: July 31st, 1973
Type: McDonnell Douglas DC- 9-31
Registration: N975NE
Operator: Delta Air Lines
Where: Boston-Logan IAP, MA (USA)
Report No.: (NSTB-AAR-74-3)
Report Date: -
Pages: -

This is not an accident investigation report.

As Delta Flight 723 was descending, the approach clearance was given by the controller after a delay, because the controller was preoccupied with a potential conflict between two other aircraft. This caused the flight to be poorly positioned for approach. The aircraft passed the Outer Marker at a speed of 385km/h (80km/h too fast) and was 60m above the glideslope. The flight director was inadvertently used in the 'go-around-mode', which led to abnormal instrument indications. This caused some confusion. The first officer, who was flying the approach became preoccupied with the problem. The DC-9 continued to descend and struck a seawall 3000ft short of and 150ft to the right of Runway 04R, crashed and caught fire. RVR at the time was 500m with 60m overcast. PROBABLE CAUSE: "The failure of the flightcrew to monitor altitude and to recognize passage of the aircraft through the approach decision height during an unstabilized precision approach conducted in rapidly changing meteorological conditions. The unstabilized nature of the approach was due initially to the aircraft's passing the outer marker above the glide slope at an excessive airspeed and thereafter compounded by the flightcrew's preoccupation with the questionable information presented by the flight director system. The poor positioning of the flight for the approach was in part the result of nonstandard air traffic control services." (NSTB-AAR-74- 3)
Source: Air Disasters / D.Gero (118-120)