Capital Airlines Flight 75
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|Date||May 12, 1959|
|Summary||Weather-induced loss of control
In-flight structural failure
|Aircraft type||Vickers 745D Viscount|
Capital Airlines Flight 75 was a domestic scheduled Capital Airlines flight operating between La Guardia Airport and Atlanta Airport. A Vickers Viscount flying the route crashed in Chase, Maryland, on May 12, 1959, with the loss of all on board. The crash was the second of three involving a Capital Airlines Vickers Viscount in as many years; the other two were Capital Airlines Flight 20 and Capital Airlines Flight 67.
The flight left the terminal at La Guardia at 3:20 in the afternoon, 20 minutes after it was scheduled to begin, and took off at 3:29. It then climbed to 14,000 feet before coming onto the assigned airway, Victor 3. By 4:02 the crew contacted Washington Center, reporting over Westchester and estimating Westminster at fifteen minutes away. In the same message they noted that there were thunderstorms along the assigned course, and requested permission to stay in the clear a little south of Westminster. The air traffic controller acknowledged the message and gave the go-ahead. At 4:10 the flight called again, the pilots noting that they had slowed somewhat to account for turbulence. This was the last message sent by the flight crew; three minutes later, the plane entered an area of severe turbulence, lost control, and entered a steep descent.
It is believed that the craft reached an airspeed of 335 knots, fully 15 percent more than the Viscount's never-exceed speed, and about 5 percent in excess of the maximum speed demonstrated when the plane was certified. Consequently, at about 5000 feet both of the horizontal stabilizers failed at once, separating downard. The separation caused the plane to pitch violently downward; the gyroscopic loads combined with inertia to cause all four engine nacelles to break upward. Both wings were then subjected to extreme downloads. Under the pressure the right wing separated, and the integrity of the left was completely destroyed.
With so much of the aircraft's superstructure gone, the left wing induced drag on the fuselage, yawing it violently to the left. More forces from that direction tore off the vertical fin, which came away with portions of the fuselage, already weakened from losing the left stabilizer, still attached. Further gyrations caused the left wing to disintegrate, opening its fuel tanks and leading to a flash fire. What was left of the fuselage crumbled, and the craft plunged to the ground in rural Maryland.
The cause of the accident was determined to be a loss of control of the plane in turbulence, resulting in an involuntary steep descent which created aerodynamic loads in excess of those for which the craft had been designed.
- "Capital Viscount Accident Report" - the findings reported in a 1959 issue of Flight