Page:CAB Aircraft Accident Report, American Airlines Flight 320.pdf/19

- 19 - reading is necessarily that of the aircraft heading at impact. The effects of impact forces and the exact instant at which each of the compass systems ceased operation are unknown. In addition, the first officer's RMDI was previously found to be in error and the extent to which this malfunction influenced the final reading of that instrument is not known.

Consideration was given to the possibility that the aircraft drifted after initial impact. It was determined that the tides and currents in the channel during and following the accident were such as to have a negligible effect so far as the wreckage location is concerned. Had any drifting of wreckage occurred, it would have been in the direction which would bring it closer to the localizer centerline. The Board believes the aircraft components of substantial mass such as the engines, sank imediatay and is of the new that drift after initial impact was negligible.

Captain Dewitt was using the ILS localizer for direction in conjunction with the ADF's to determine precisely the aircraft's position over the navigational fixes. His No. 1 ADF was tuned to the La Guardia compass locator; the No. 2 ADF was tuned to the La Guardia Range. In order for ADF information to be displayed visually on the RMDI, the selector on this instrument must be placed in the ADF position.

Investigation disclosed the selector switch for the captain's No. 1 ADF needle was selected to the ADF position; however, the No. 2 selector was in the VOR position. Under these conditions the single needle would be displaying the position of the La Guardia middle marker which is southwest of the airport and, therefore, would be approximately straight ahead of the flight throughout the final approach to the moment of impact; however, the No. 2 or double needle would be inactive, eliminating its use in displaying the position of the La Guardia Range. Testimony also indicated difficulty in receiving the range station, although station passage was observed by the first officer on his RMDI. The No. 2 ADF control settings were ten kilocycles above the La Guardia range frequency and in the loop position, this suggesting a possible manipulation of the ADF controls to confirm station passage.

Operations Specifications issued to American Airlines on January 23, 1959, require that the ceiling and visibility landing minimums prescribed in the Operations specifications be increased by 100-foot ceiling and one-half mile visibility whenever the captain in scheduled operation has not served for 100 hours as pilot-in-comnard on the equipment, or until such time as the captain is certified by his Regional Superintendent of Flying as qualified to operate at the landing minimums prescribed. If these restrictions are to serve any purpose other than to give the appearance of a conservative flight operations policy, the Board questions the wisdom the company in exempting Captain DeWitt when he had but 12:32 hours of flying the Electra in scheduled operations. This occurred nine days before the accident.

The Board has recommended that the Administrator review existing FAA policy to determine whether the waiver provision contained in the Operations Specification should be deleted.

Another possibility of accident causation is concerned with adequacy of operational techniques.

Approaching New Rochelle and for the remainder of the instrument approach, the aircraft was flown on autopilot in the heading mode and with the flaps in