Allegheny Airlines Flight 561 Accident (N29824)

Incident Overview and Timeline On February 12, 1979, Allegheny Airlines Flight 561, operating aircraft N29824, departed Benedum Airport in Clarksburg, West Virginia, at 1116 for Morgantown, West Virginia. The pilot aborted the approach at Morgantown due to an inoperative instrument landing system (ILS) glide slope and visibility of 1/2 mile. The flight returned to Benedum Airport, landing at 1146. ## Ground Operations and Deicing The aircraft remained on the ground for approximately 1 hour and 14 minutes. During this period, it was refueled with 3,000 pounds of Jet-A fuel and deiced using a mixture of unheated ethylene glycol and water. Personnel involved stated the deicing was performed between 1220 and 1235, and they reported no snow or ice remained on the aircraft upon completion. ## Takeoff and Crash Sequence Flight 561 was rescheduled as a passenger flight to National Airport in Washington, D.C., carrying 22 passengers and a crew of 3. Before taxiing, the station agent offered to re-deice the aircraft due to ongoing snowfall, but the captain declined. At approximately 1257, the aircraft taxied from the parking ramp. The station agent observed about 1/4 inch of wet snow on all horizontal surfaces, noting that some snow blew off during taxiing while some remained adhered. Witnesses reported the takeoff roll appeared normal. The Clarksburg Tower local controller cleared the flight for takeoff on runway 21 and provided a 1215 special observation weather report, noting moderate snowfall but no visible snow on the aircraft. The approach controller observed the aircraft rotating approximately 1,900 feet down the runway and lost sight of it at 50 feet altitude due to poor visibility. Shortly after liftoff, twelve passengers recalled the aircraft rolling to the right, then left, then right again. After the final roll, the right wingtip struck the ground, followed by impact. The aircraft crashed in an inverted position off the right side of the departure end of runway 21. ## Casualties and Findings The crash occurred during daylight hours at an elevation of 1,203 feet. One passenger and one crew member were killed, while 23 other occupants were injured, some seriously. The National Transportation Safety Board determined the probable cause was the captain's decision to take off with snow on the wing and empennage surfaces, resulting in a loss of lateral control and lift as the aircraft ascended out of ground effect. Key findings included: - The aircraft had been deiced 20 to 30 minutes before takeoff, but approximately 1/4 inch of wet snow had accumulated on the wings and horizontal stabilizer before taxiing. - The captain did not ensure the wings, stabilizing surfaces, and control surfaces were clean and free of snow before the takeoff roll. - Snow adhering to the outboard wing sections likely caused premature stalling, reducing lift and aileron effectiveness. - The resulting lateral oscillation further decreased lift, causing the aircraft to lose altitude and crash. - One passenger was fatally injured because her seatbelt was not fastened. - The accident was marginally survivable for the flight crew due to inward crushing of the cockpit structure, which reduced occupiable space, particularly for the first officer.