Boeing 720-B accident at Boston, Massachusetts, 24 Sept 1961 (N-7545A)

Accident narrative

On September 24, 1961, at approximately 1105 e.d.t., American Airlines Flight 44, a Boeing 720-B (N 7545A), overshot runway 4R during a precision radar approach at Logan International Airport in Boston, Massachusetts. The aircraft slid into Winthrop Bay. There were no serious injuries to the 63 passengers or 8 crew members, but the aircraft sustained major damage.

### The flight

Flight 44 originated in San Francisco, California, destined for Boston with a scheduled en route stop at O’Hare Airport in Chicago, Illinois. The aircraft departed Chicago at 0918. Its gross takeoff weight was within prescribed limits.

The crew consisted of Captain Ted E. Jonson, First Officer Joseph E. Ferdyn, Second Officer James B. Edgar, Flight Engineer Lynn J. Stenseth, and four stewardesses. The captain had approximately 22,000 hours of pilot time, with 1,800 hours in the Boeing 707-720. The first officer, who flew the aircraft during the approach, had approximately 12,000 pilot hours, including 2,000 in the Boeing 707.

Prior to departing Chicago, the crew was notified that the instrument landing system (ILS) at Boston was inoperative. The flight proceeded routinely to the Boston area.

### The approach

Approaching Boston, Approach Control advised Flight 44 that the weather included a measured 300-foot overcast, visibility of one mile in fog, and a runway visual range (RVR) of more than 6,000 feet. The controller asked if the flight would accept a precision approach radar (PAR) approach to runway 4R, and the crew accepted. The controller advised that the runway length was 10,021 feet, with the point of touchdown 3,417 feet from the approach end to allow for shipping through the channel.

At 1102, the flight was handed over to the PAR controller. During the final approach, the PAR controller repeatedly advised the flight that it was above the glidepath. As the aircraft neared the runway, the controller transmitted: "passing the middle marker - turn right heading of zero four zero... you are still 25 feet above the glidepath... you are past the physical end of the runway now... still 25 feet above the glidepath... over touchdown if you don't have the runway in sight execute a missed approach."

At approximately 1105, Flight 44 transmitted, "Looks like we're going to slide off here Buddy." The aircraft ran off the end of the runway, turned right, and came to rest in Winthrop Bay in approximately 16 feet of water, 420 feet beyond the physical end of the runway. The occupants evacuated into boats within 10 minutes.

### What the investigation found

The Board found no evidence of malfunctioning or failure of the engines, aircraft, or its systems. The flight recorder was recovered undamaged, but intermittent binding of the record foil rendered its data erratic and unusable.

Examination of the wreckage showed that the wing flaps were fully extended and the speed brakes were retracted. The reverser doors of all four engines were in the full reverse position, and the anti-skid switch was on.

The captain and first officer testified that the approach was commenced at 144 knots, which was 10 knots above the reference speed. They stated they first saw the runway when passing the middle marker at an altitude of 300 to 350 feet, but did not see any approach lights, threshold lights, runway lights, or the approach end of the runway. They determined their position from the PAR controller's information and were not visually aware of their position until the end of the runway suddenly appeared before them. The first officer stated he applied reverse thrust and saw the captain activate the speed brakes; however, the captain did not recall extending them, and a passenger stated they were not extended.

Witnesses, including the local tower controller and an off-duty pilot aboard the flight, observed the aircraft emerge from the overcast, flare, and float above the runway before disappearing into a patch of fog. Tire marks revealed that the aircraft's right gear first touched down 3,165 feet beyond the PAR touchdown point. The aircraft then skipped for approximately 614 feet before rolling straight and eventually curving off the runway.

The Board calculated that to float 3,165 feet, the airspeed at the time of the flare must have been approximately 154 knots. Based on the tire tracks and the distance traveled, the Board concluded that the speed at touchdown was in excess of 134 knots or that maximum stopping capability was not utilized.

Weather records showed that visibility was fluctuating rapidly as fog moved over the airport. Between 1057 and 1102, the RVR dropped from more than 6,000 feet to as low as 2,200 feet. This rapid deterioration was recorded on the master instrument in the Weather Bureau office and a slave indicator near the approach controller, but the PAR controller did not have an indicator at his position. Contrary to instructions, neither the approach controller nor the PAR controller supplied the flight with the deteriorating RVR values.

The Board believed that visibility was below the required 4,000-foot RVR minimum during the final approach, and that fog obscured both ends of the runway. Because the PAR touchdown point on runway 4R was located 3,417 feet from the physical end of the runway, the crew lacked the definite visual cues normally provided by sighting the runway threshold. The Board noted that the approach was continued without visual reference being established, and was flown higher and faster than normal.

### Probable cause

The Board determined that the probable cause of this accident was "the captain's decision to land in variable weather conditions precluding adequate orientation relative to location along the runway."

A contributing factor was "the failure to provide the flight with information concerning the deterioration of runway visual range values."