Investigation Summary
Flight 410 was operating a multi-stop route from Chicago to Norfolk. After an uneventful leg from Cleveland to Pittsburgh, the crew was informed of traffic delays and deteriorating weather at Washington National Airport. The pilot requested an alternate approach via Airway 61 Red, a route recently authorized for Pennsylvania Central Airlines. During the descent, the pilot reported passing through 1,000-foot increments from 7,000 feet down to 3,000 feet. The aircraft subsequently struck a cliff face on the western slope of the Blue Ridge Mountains. Investigation revealed the aircraft was in a laterally level attitude with a 2.5 degree descent angle at the moment of impact, with engines developing considerable power. While the route was approved, neither the Civil Aeronautics Administration (CAA) nor the airline had defined a minimum en-route altitude for that specific airway. The pilot descended below the ridge tops without adequate visual ground references in instrument conditions.
Final Conclusions
The Civil Aeronautics Board determined the probable cause was the pilot's decision to descend below the minimum altitude for which the flight had received clearance without having adequate ground references. Contributing factors included the failure of Airway Traffic Control and the PCA dispatcher to recognize the inappropriateness of the clearance provided for that specific route, as well as the lack of established minimum altitudes for the newly approved airway.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Altimeter
Though pilot error was the primary finding, investigators and contemporary reports considered a faulty altimeter as a potential factor in the premature descent.
Airway 61 Red
The specific flight path requested by the pilot which lacked established minimum safe altitudes at the time of the crash.
Interesting Facts
- 01The crash occurred on Friday the 13th, which added to the contemporary notoriety of the event.
- 02At the time of the accident, it was the second-deadliest commercial aviation disaster in United States history.
- 03The impact was described as a 'pancake' into the cliff side at full throttle, suggesting no evasive action was taken.
- 04The wreckage was located approximately 8 miles south of Charles Town, West Virginia, near the Virginia border.
- 05Six victims could not be identified and two bodies were never recovered due to the intensity of the fire and impact.
Safety Actions & Advisories
Standardized Minimum Altitudes
On October 8, 1947, the CAB established uniform minimum en-route and approach altitudes for all U.S. air carriers to prevent similar terrain strikes.
Terrain Warning Indicators
On October 10, 1947, the CAB mandated the installation of absolute terrain warning indicators (early precursors to GPWS) in all scheduled air carrier aircraft.