Investigation Summary
Flight 802 was cleared for an approach to Cold Bay under low overcast conditions with ragged ceilings at 500 feet. The captain, who was flying the aircraft, elected to bypass the standard procedure turn and instead attempted to intercept the localizer back course for runway 32 directly. During the descent, the aircraft entered a region where the Cold Bay VORTAC signals were known to be unreliable due to terrain masking, a fact the captain was apparently unaware of despite his familiarity with the area. The First Officer noted that the DME was 'not good' as they descended through 4,500 feet, yet the captain continued the descent to 3,500 feet, which was the minimum altitude for a different segment of the approach. Erroneous navigation readings, caused by signal reflections from the mountains, likely led the captain to believe he was southeast of the station when he was actually east-southeast. Moments before impact, the First Officer warned that the radio altimeter was 'alive' and that they were off course, but the realization came too late to avoid the rising terrain of Mount Dutton.
Final Conclusions
The National Transportation Safety Board (NTSB) determined the probable cause was the captain's deviation from approved instrument approach procedures. This deviation resulted in the flight descending into an area of unreliable navigation signals and obstructing terrain. Contributing factors included the captain's lack of awareness regarding minimum sector altitudes and specific terrain hazards, such as Mount Dutton, in relation to the navigation signal restrictions published for Cold Bay. The NTSB issued its final report, AAR-74-06, on May 8, 1974.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
John A. Weininger, age 52.
First Officer
Gregg W. Evans, age 27.
Flight Engineer
Robert W. Brocklesby, age 46.
Systems & Failure Modes
VORTAC
The primary navigation aid for the approach; its signals were unreliable below 9,000 feet in the sector east of the station due to terrain interference.
DME (Distance Measuring Equipment)
Used by the crew to determine distance from the station; it functioned intermittently during the descent but provided accurate readings just before impact.
Radio Altimeter
Provided the crew with their final warning of proximity to the ground, becoming 'alive' approximately 22 seconds before impact.
Interesting Facts
- 01The aircraft was a DC-8-63CF that had entered service only two years prior to the accident.
- 02The captain had flown into Cold Bay 20 times in the previous 9 years but had never performed the localizer back course approach to runway 32.
- 03The aircraft struck the mountain at the 3,500-foot level, which was the exact altitude the captain had intentionally selected for the approach segment.
- 04Post-crash examination of the First Officer's navigation receiver showed it was receiving a 293.5 degree bearing, while the actual bearing from the impact site to the VORTAC was 267 degrees.
- 05The NTSB found that signal reflections from the mountains were strong enough to keep VOR warning flags biased from view despite the unreliable data.
Safety Actions & Advisories
Safety Recommendation A-74-53
Source ↗The NTSB recommended that the FAA review Instrument Approach Procedure charts to ensure that critical information regarding 'unusable' NAVAID signal areas and minimum reception altitudes is clearly depicted for pilots.