Subnormal Takeoff Performance Leads to Crash at Stapleton (N67960)

Pre-Takeoff and Departure Phase The crew completed their before-takeoff checks and reported that all aircraft components were operating normally. At 0329, the aircraft rolled onto the runway for takeoff. From the control tower, the aircraft appeared to accelerate slowly and took an excessively long time to become airborne. The pilots reported that the engines were operating normally, developing 45 inches of mercury of manifold pressure and 2,700 RPM, but airspeed increased slowly. ## Takeoff and Initial Climb Between 90 and 100 mph, and just before the end of the runway was reached, the aircraft was pulled off the runway by Captain Robins as he applied back pressure on the control column. After takeoff, the highest airspeed attained was between 100 and 105 mph. The landing gear was placed in the up position when the flight became airborne, and a climb was made to about 100 feet. During the climb, the aircraft shuddered severely. Altitude was lost, and the aircraft struck an obstruction light on the top of a 40-foot electric light pole located 1,910 feet south of the end of the runway. ## Impact and Aftermath The aircraft struck three more poles, then touched ground and skidded for 350 feet. It came to a full stop 2,791 feet from the south end, in line with Runway 17. The crash landing occurred in an alleyway of a residential district located between Stapleton Air Field and Lowry Air Force Base, which is located 1-1/4 miles south of Stapleton. In addition to striking the electric light poles, the aircraft knocked down several fences, a small tool shed, and collided with two parked automobiles. Crash and fire equipment dispatched from both Stapleton and Lowry Airports and the city of Denver arrived promptly. Partly as a result of their precautionary action, no fire occurred. ## Official Findings The Board determined that the probable cause of this accident was the subnormal takeoff performance of the aircraft, the reason for which cannot be determined. The following factors were identified: - The aircraft was overloaded by 172 pounds, but this amount did not appreciably affect the aircraft's takeoff performance. - Under the conditions of aircraft weight and density altitude that existed at the time of the accident, the flight should have obtained an altitude of 50 feet and an airspeed of 123-1/2 mph after traversing a distance of 5,850 feet from the start of the takeoff roll, according to data contained in the CAA approved flight manual. - The aircraft, N-67960, was reported to be consistently slower in accelerating and taking off than other aircraft of the same type. - A runway 6,980 feet long was selected for takeoff, although the practically calm wind condition permitted the use of another runway which is 8,500 feet long. - The takeoff run was made with the aircraft in an unusually tail-low attitude, and nearly the entire runway length, 6,980 feet, was used before the aircraft was pulled off the ground. - In a climb to 100 feet altitude after takeoff, a partial stall developed. - The aircraft settled, collided with obstructions, and crashed. - No defects were found in the aircraft, the engines, or the propellers.