Investigation Summary
Flight 737 was a scheduled multi-stop service from Washington D.C. to Detroit, with intermediate stops at Harrisburg, Bradford, and Erie, Pennsylvania. After departing Harrisburg, the aircraft proceeded toward Bradford. The weather at the time was poor, characterized by an overcast sky, light snow showers, and visibility of approximately 1.5 miles. During the approach, the crew requested and received clearance to switch their approach from runway 32 to runway 14. At 20:31, the crew reported they had completed their procedure turn and were inbound. Shortly thereafter, the aircraft clipped treetops approximately 4.7 nautical miles short of the runway. The Convair cut a swath through trees bordering the Pine Acres Golf Course before flipping over and coming to rest upside down. The proximity in time and location to the crash of Flight 736 led to intense scrutiny of Allegheny's operational procedures and the CV-580's instrumentation.
Final Conclusions
The National Transportation Safety Board (NTSB) published its final report (AAR-70-10) in 1970, stating it was unable to determine the probable cause. The board analyzed 13 potential causes and narrowed them to three equally plausible scenarios: (1) the captain misread the altimeter, (2) the captain's altimeter malfunctioned after the procedure turn, or (3) the crew misinterpreted the instrument approach chart. No evidence was found to definitively support one over the others.
Video Analysis
Second Crash In A Row | Allegheny Airlines Flight 737 — A look at the 1969 crash of Allegheny Airlines Flight 737 near Bradford, Pennsylvania, occurring just two weeks after a similar accident at the same airport.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
William I. Blanton Jr., age 33.
First Officer
Ronald Lesiak, age 31.
Systems & Failure Modes
Altimeter
Investigators focused on the captain's altimeter, considering both a mechanical malfunction and a human factors misreading as potential causes for the premature descent.
Allison 501-D13 Engines
The aircraft was equipped with these turboprop engines as part of its conversion from a CV-440 to a CV-580.
Interesting Facts
- 01The aircraft was originally a Convair CV-440 (MSN 386), later converted to a CV-580 with turbine engines.
- 02The aircraft was re-certificated as a CV-580 on July 11, 1967, following its conversion.
- 03The crash occurred only 13 days after Allegheny Airlines Flight 736 crashed at the same airport.
- 04The aircraft came to rest completely inverted in deep snow.
- 05Two out of the three crew members (both pilots) were among the 11 fatalities.
- 06The NTSB investigated 13 potential causes before narrowing the list to three undetermined possibilities.
Safety Actions & Advisories
Allegheny Airlines Visibility Minimums
Following the crash, Allegheny Airlines self-imposed stricter landing rules, requiring 1,000 feet ceiling and 3 miles visibility for airports without instrument landing systems (ILS).