Page:BCPA Flight 304 accident investigation report.djvu/3

 feet farther north. The main wreckage area, at an elevation of about 1,950 feet MSL, was approximately one-fourth mile farther to the north. It was determined the aircraft was flying on an approximate heading of northeast by north when at first struck the trees.

Examination revealed the landing gear was down and locked at impact. From impact impressions in the left flap as well as an extended flap actuator piston, it was determined the flaps were extended between 15 and 20 degrees.

Though severely fire damaged, the major portions of the control surfaces were located with the main wreckage. Many broken and burned control cables were examined and these, together with other components of the control system, failed to reveal any evidence of failure or malfunction prior to impact. As far as could be determined from an examination of the damaged airframe components, there was no evidence to indicate that the aircraft was not airworthy prior to the crash.

Impact forces were of such magnitude that the four engines were widely separated in the wreckage area. Molten masses of aluminum were evidence of the intense fire after impact. All propeller blades were found and from propeller domes, hubs, and blade positions examined, it was determined that they were set at blade angles between 29 degrees and 37 degrees at impact. The propeller governors from Nos. 2 and 3 engines were found and although badly burned, comparative tests were possible which revealed r.p.m. settings of approximately 2400. As far as could be determined from an examination of the damaged engines and components, there was no indication that a malfunction or failure had occurred prior to impact. The aircraft was in an airworthy condition according to the laws of the Australian Government when it departed Sydney.

Two communication receivers were found tuned to 278 kc., the frequency of the San Francisco tower. The marker beacon receiver hi-lo switch was in the "hi" position. The ADF receivers were so badly damaged it was impossible to determine their settings. One altimeter was recovered with a barometric setting of approximately 30.12; the latest setting given the flight was 30.14. This difference amounts to approximately 20 feet of altitude. A clock was impact stopped at approximately 1640 (0840).

CAA navigation and landing facilities in this area were given careful investigation. A thorough flight check was given the facilities by a CAA patrol aircraft as soon as possible after the crash; no discrepancies could be found. Maintenance and daily inspection reports indicated normal operation during the time the approach was being made. The pilot of a scheduled flight from Honolulu who landed a few minutes prior to the accident, stated that during his approach the Half Moon Bay Fan Marker, the Belmont Fan Marker, and the ILS system, gave normal aural and visual indications. Because of information received from a scheduled pilot that an overlap of the aural and visual signals of the Half Moon Bay Fan Marker and the Belmont Fan Marker had been experienced by him four or five years prior, a flight check was made by BCPA using their DC-6 with identical radio equipment to the aircraft involved. A CAB investigator was on board as an observer and the purpose of the flight was to simulate as nearly as possible the flight of VHBPE from the point of starting descent some 71 nautical miles southwest of Half Moon Bay. The radio navigational facilities were checked throughout this flight and neither the alleged overlapping nor any other discrepancies were revealed.