N166DHDehavilland DHC-6 TWIN OTTER · 1967

On June 8, 2025, about 1220 central daylight time, a DeHavilland DHC-6 Twin Otter, N166DH, was involved in an accident near Tullahoma, Tennessee. The commercial pilot and five passengers were seriously injured, and 15 passengers were not injured. The flight was being conducted as a 14 Code of Federal Regulations Part 91 skydiving flight.

The pilot was attempting to take off from runway 24 at the Tullahoma Regional Airport (THA), Tullahoma, TN. The accident flight was his fourth flight in the airplane that day. The pilot stated the takeoff was normal and he raised the flaps once the airplane was clear of obstacles. When the airplane was about 500 ft above the ground, the pilot noticed asymmetrical thrust on the engines while syncing the propellers. He said, “In the following seconds, I continued trying to sync the props and was getting unusual feedback in the controls. I didn’t notice any loss of power in the gauges, but something felt a miss.” The pilot lowered the nose of the airplane and saw the altitude level off, and airspeed decrease.

The pilot determined that the left engine had lost power. He initiated “engine out procedures” and turned left, back to the airport to try and land on runway 36. The pilot could not remember if he secured the left engine; however, he did remember adding flaps as per the engine-out procedures. The pilot said he tried to maintain airspeed above the single-engine minimum control speed (Vmc), but the airplane continued to descend. The pilot was unable to make it back to the airport and chose to land in a field. There were two trees in the field that he was unable to avoid, and the airplane impacted the trees. The airplane came to rest upright, but the left wing, left engine and the tail section separated from the airframe, resulting in substantial damage. The right wing and engine remained secured to the airframe. There was no postimpact fire.

The airplane wreckage was recovered and taken to a secure facility for further examination.

The pilot in the landing airplane reported that, he had turned on the airport runway pilot-controlled lighting about 5 miles prior to arriving at the airport, and transmitted 2-mile final radio call, over the airport's CTAF. He landed the airplane and made "S" turns on runway 28 because, "it is not possible to see the opposite threshold" when established on the runway. When the pilot began a right turn to exit the runway at the mid-field taxiway, an airplane that had initiated a takeoff roll from the opposite end of the runway collided with the landing airplane. The airport's runway does not have a parallel taxiway and it is standard practice to back taxi to the departure end.

During a conversation with the IIC, the pilot in the departing airplane reported that he was performing a skydiving operation. He transmitted his intentions to taxi to the mid-field intersection and to depart runway 10. He did not activate the pilot-controlled runway lighting but recalled that he had noticed that the pilot activated lighting had been turned on, and he taxied to the hold short line and did not see any airplanes. He back taxied to the approach end of runway 10 and maneuvered his airplane to takeoff from runway 10. During the takeoff roll the left wing of his airplane struck the landing airplane.

The departing airplane sustained substantial damage to the left wing spar.

Neither pilot recalled hearing radio transmissions on the airport's CTAF.

Both pilot's reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.