- 43 -
2.5.3
The lack of an indication on the flight director and autopilot mode annunciator panels of the operative status of the heading select mode deprived the crew of a cue which might have drawn their attention to the fact that the autopilot was not being controlled by the INS. A review of incidents involving navigation errors of a similar nature found that it was not uncommon for a crew to overlook a failure to revert to INS navigation after using the heading select mode for weather avoidance or re- routing by ATC. Most aircraft of more recent manufacture display heading select modes on the annunciator panels.
2.6
Anchorage radar record
2.6.1
The radar record available from Anchorage in 1983 showed that there was initial closure by KE 007 towards route J501 from the north while it maintained a heading of 220° magnetic. The recorded change in heading from 220° to about 245° matched the ATC clearance "proceed direct BETHEL when able". The heading selected caused the aircraft to deviate to the right of its cleared track direct to BETHEL. The aircraft maintained this magnetic heading and passed approximately 6 NM abeam Cairn Mountain NDB and 12 NM abeam of Bethel VORTAC. According to representatives of the United States, there was no requirement for Anchorage ATC to inform KE 007 of its position when the radar service was terminated at 13:27 hours since a direct BETHEL clearance had been given and the track to be flown was not defined.
2.7
2.7.1
Navigation requirements
Korean Air Lines used the North Pacific Airspace Operations Manual (March 1983) as the basis for their guidance for flight crews operating in the North Pacific composite route system. The manufacturer's B-747 Operations Manual was also included in the Korean Air Lines' Operations Manual. The North Atlantic MNPS Airspace Operations Manual (September 1980) had also been used as guidance material for Korean Air Lines' flight crews in 1983. These three manuals each contained procedures for the conduct of inertial navigation. Particularly relevant were the procedures for checking navigation system accuracy at the commencement of oceanic navigation. These procedures required careful overflight of the last available external navigational aid, in this case Bethel VORTAC, and specific checks of INS accuracy. The procedures also provided for an outbound track check when the oceanic fix was a VOR. These procedures, included in the KAL Operations Manual, were not observed since KE 007 did not pass over Bethel VORTAC.
2.7.2
On approaching Bethel VORTAC, information on the track displacement would have been available from the VOR RMIS, the track bar of HSI's VOR/ILS display and the DME. Further information on track displacement would have been available from the track bar of the HSI's INS display, the cross-track error displays on the INS CDUS, error in position co-ordinates between the actual position and the desired position and the distance to go on the INS displays. Any error in one of the three INS would have been apparent from comparison with the other two systems. The accuracy of the INS was better than 2 NM per hour of flight. The lateral displacement of 12 NM from Bethel VORTAC after 49 minutes of flight should have alerted the flight crew to a possible problem and prompted an immediate assessment of the situation. The guidance material on INS navigation in the North Pacific and North Atlantic oceanic areas emphasized that ATC be informed in any case of doubt as to the accuracy of the INS.
No comments yet.
Private notes are available after approval.