Investigation Summary
The flight was the final leg of a transcontinental service originating in Boston, with San Francisco as its ultimate destination. After routine stops in Hartford, Cleveland, and Chicago, the aircraft proceeded toward Oakland, its final scheduled stop before San Francisco. During the approach, the crew was cleared for a straight-in range approach from the Newark fan marker, with instructions to maintain at least 500 feet above the cloud tops. At 04:22, the crew briefly requested a straight-in ILS approach, but this was retracted shortly after in favor of the radio range approach. The investigation determined that the captain failed to adhere to established instrument approach procedures. Instead of following the southeast on-course signal of the Oakland radio range, the aircraft drifted three miles to the right. The captain was likely relying on the Automatic Direction Finder (ADF) rather than the primary radio range signals. Furthermore, the aircraft descended to 983 feet MSL, well below the prescribed minimum altitude of 3,500 feet for that segment of the approach. The DC-6B struck the crest of a hill, hurtled into Dry Gulch Canyon, and was destroyed by impact and fire.
Final Conclusions
The Civil Aeronautics Board (CAB) determined the probable cause was the failure of the captain to adhere to instrument procedures in the Newark area during an approach to the Oakland Municipal Airport. A critical finding by investigators was that neither of the aircraft's radio receivers was tuned to the Oakland radio range station at the time of impact. Contributing factors included the pilot's decision to attempt a visual approach in instrument conditions and the use of the ADF which led to a significant lateral deviation from the intended course.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Marion W. Hedden
First Officer
Robert E. Sands
Systems & Failure Modes
ADF (Automatic Direction Finder)
A radio-navigation instrument that automatically displays the relative bearing from the aircraft to a radio station. The pilot likely relied on this instead of the radio range signal.
Oakland Radio Range
A ground-based navigation system that provided directional signals (beams) for pilots to follow during instrument approaches.
Interesting Facts
- 01The aircraft was a brand new Douglas DC-6B with only 361 total airframe hours.
- 02The crash site was located approximately 15 miles (24 km) southeast of Oakland International Airport.
- 03The aircraft was three miles to the right of the intended southeast on-course signal at the time of impact.
- 04The cloud base in the area was reported at 1,500 feet with patches of fog obscuring the terrain.
- 05The aircraft was named 'Mainliner Omaha'.
Safety Actions & Advisories
Adherence to Instrument Procedures
The investigation emphasized the critical necessity for flight crews to strictly adhere to published instrument approach procedures and minimum altitudes, especially in areas of rising terrain.