The pilot was attempting a takeoff from an industrial truck yard in Dickinson, North Dakota, in 24- to 31-knot gusting headwind conditions.
He performed a short field takeoff procedure with the Piper PA-12’s wing flaps extended about halfway.
As the airplane reached about 30 knots, the tailwheel lifted off the ground, then the pilot fully extended the flaps and the airplane became airborne. Shortly afterward, the right wing dropped.
As he was recovering from the right bank, the pilot retracted the flaps from fully extended back to half extension and confirmed that the throttle was full forward. At that time, the airplane turned sharply to the right and descended into a parked trailer.
A witness reported that, shortly after becoming airborne, the airplane entered a 35° right bank. The pilot corrected slightly, however at that point, the airplane started a more abrupt climb, “snap rolled” to the right, and hit the trailer inverted.
The bank and roll to the right are consistent with an aerodynamic stall.
A post-accident examination did not reveal any anomalies consistent with a pre-impact failure or malfunction. The exact position of the wing flaps at the time of impact could not be determined.
The dirt- and gravel-surfaced takeoff area was about 750′ long and was rough and uneven. The uneven takeoff area may have reduced the airplane’s acceleration during the takeoff ground roll, and the gusty wind condition may have contributed to the stall once airborne.
In addition, given the limited takeoff distance available, the pilot may have rotated the airplane at a slower-than-normal airspeed, thereby increasing the possibility of an inadvertent stall.
Additionally, the extension and retraction of the wing flaps during takeoff resulted in abrupt changes in the airplane’s angle of attack and a subsequent aerodynamic stall, which precipitated the pilot’s loss of control.
Probable cause: The pilot’s failure to attain adequate airspeed during the short field takeoff, which resulted in an exceedance of the airplane’s critical angle of attack and an aerodynamic stall.
NTSB Identification: CEN18LA039
This November 2017 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.