Page:CAB Aircraft Accident Report, American Airlines Flight 2815.pdf/3

- 3 - The first officer stated that he observed ground lights as the aircraft passed intermittently in and out of cloud bases and suddenly saw a red light on top of a transmission tower. Previously he had called out "minimum altitude" when his altimeter read 1,000 feet (400 feet above airport level) and then con- centrated his attention to looking for the runway. He stated that he believes he started the gear up as ordered. Almost simultaneously the airplane struck the tower, was substantially damaged, and nosed down sharply. Up elevator was applied and descent was lessened somewhat as the aircraft plunged into a railroad yard. It skidded across tracks, coming to rest close to a moving freight train about 2,600 feet from the tower. Both pilots got out through the captain's window just ahead of a fast growing fire which consumed the aircraft and its cargo.

The steel tower is 96 feet higher than the airport, 6,350 feet from the approach end of runway 31, and approximately 3,000 feet to the left of the extended centerline of the runway.

Examination of the wreckage disclosed that both IIS receivers were at the proper frequency. Little could be learned from the remains of the ADF receivers because of fire damage, although Captain Larsen had been using both of them, apparently satisfactorily. Nothing whatever could be learned from the remains of the altimeters nor their static systems. The wing flaps were found at a setting of approximately 20 degrees, and the landing gear was down and locked.

Examination of the engines and propellers showed that they were operating in an approach condition at the time of impact. The right propeller governor was set to obtain 2,220 r. p. m. and the right propeller was at 31 degrees pitch. The left governor was set to obtain 2,310 r. p. m. and the left propeller was at 30 degrees pitch.

All ground radio navigational facilities utilized during the final approach were checked by the Federal Aviation Agency and found to be functioning normally. These included the approach radar although rain clutter had prevented tracking the Convair with it. Neither pilot suggested that there may have been any malfunctioning of any nature with the aircraft or any of its components, barring the altimeters, and none was found.

The correct altimeter setting was given the flight before the approach to Midway and the crew set their altimeters accordingly. Investigation also showed that the ground altimeters from which the setting was given were indicating accurately. Both of the aircraft's altimeters functioned properly and were cross-checked during the flight from La Guardia including the landing in rain at Detroit.

During the ten days preceding this accident, N 94273 had had 32 flights for a total of 59:24 hours. All of the mechanical irregularities written up on the log sheets had been corrected; among these were the removal and replacement of three altimeters for reported erroneous indications. On March 8, 1959, the captain's altimeter was reported to read lower than actual altitude and was replaced. On March 12, 1959, the first officer's altimeter was reported to read 200 feet higher than the captain's at 11,000 feet, and normal at sea level; it was replaced. On March 13, 1959, the first officer's altimeter was reported to read 180-200 feet higher than the captain's at 9,000 feet; it was replaced.

Tests of all three of these replaced altimeters showed that they functioned normally and within company and FAA tolerances. A comparison of all altimeter