| Accident summary | |
|---|---|
| Date | December 1, 1974 |
| Type | Pilot error |
| Site | Haverstraw, near Stony Point, New York |
| Passengers | 0 |
| Crew | 3 |
| Fatalities | 3 |
| Survivors | 0 |
| Aircraft type | Boeing 727-251 |
| Operator | Northwest Airlines |
| Tail number | N274US |
| Flight origin | John F. Kennedy International Airport |
| Destination | Buffalo International Airport |
The Harriman State Park plane crash was a fatal crash of a Boeing 727 which took place on December 1, 1974 near Stony Point, New York. The flight, designated Northwest Airlines Flight 6231, had been chartered to pick up the Baltimore Colts football team in Buffalo, New York. All three crew members aboard were killed when the aircraft struck the ground following a stall and rapid descent caused by the crew's reaction to erroneous airspeed readings caused by atmospheric icing. The icing occurred due to failure to turn on pitot heat at the beginning of the flight.
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The flight was chartered to pick up the Baltimore Colts football team in Buffalo, New York after the aircraft for the team's originally chartered flight was grounded by a snowstorm in Detroit.[1]
The Northwest Airlines Boeing 727-251, tail number N274US, departed John F. Kennedy International Airport at 19:14 for a ferry flight to Buffalo. As the craft climbed past 16,000 feet, the overspeed warning horn sounded, followed 10 seconds later by a stick shaker stall warning. The aircraft leveled at 24,800 feet until it started to descend out of control in a spin, reaching a vertical acceleration of +5g until it struck the ground in a slightly nose down and right wing-down attitude at 19:26. The aircraft had descended from 24000 feet to 1090 feet in 83 seconds.[2]
The plane had three crewmembers aboard. The pilot, Capt. John B. Lagario, had worked for Northwest for eight years. First officer Walter A. Zadra and second officer James F. Cox Jr. had each been with the airline for six years.[3]
The crash site was located the day after the accident. Police described the site as a heavily wooded marshy area and accessibility was hampered by winter weather conditions including wind and a rain-snow mix.[1]
The National Transportation Safety Board led the accident investigation and released its final report on August 13, 1975. Parties to the investigation included the Federal Aviation Administration, Northwest Airlines, The Boeing Company, Air Line Pilots Association, International Association of Machinists and Aerospace Workers, and Pratt & Whitney.[2]
Investigators found that the pitot heads had ice damage which caused the crew to receive the wrong readings. The crew, believing the readings were true, raised their nose and pulled back on the control column, which caused the plane to stall.[4]
From the NTSB report's abstract:
...the probable cause of this accident was the loss of control of the aircraft because the flightcrew failed to recognize and correct the aircraft's high angle of attack, low-speed stall and its descending spiral. The stall was precipitated by the flightcrew's improper reaction to erroneous airspeed and Mach indications which had resulted from a blockage of the pitot heads by atmospheric icing.
When investigators found the 727's voice recorder, the recording revealed that the pilots believed that the shaking of the stick shaker mechanism was caused by the plane reaching the speed of sound, and not a warning that the plane was going into a stall.[2]
In that manner, this crash resembles the one of Air France Flight 447 (June 1st, 2009), where the pilots were warned of unreliable airspeed, but failed to perform the necessary procedures.
An example of a Pitot tube which froze on this flight.
Tail section of a similar 727.
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