N601AX

HISTORY OF FLIGHTOn February 25, 2021, about 1126 central standard time, a Dassault Aviation Mirage F1B, N601AX, was substantially damaged when it was involved in an accident at Tyndall Air Force Base (PAM), Panama City, Florida. Both pilots sustained serious injuries. The airplane was operated as a public aircraft under the provisions of Title 49 of the United States Code Sections 40102 and 40125.

The planned flight of the dual-seat, turbojet-powered fighter airplane was conducted under the provisions of a contract between by Airborne Tactical Advantage Company (ATAC) and the United States Air Force to provide ATAC owned and operated aircraft to support adversary training for U.S. military forces.

The accident airplane was the lead of a two-airplane formation departure from runway 14R at PAM. As the lead, the accident airplane was lined up on the left side of the runway and the second airplane was lined up on the right side of the runway. The accident pilot reported that he initiated the takeoff roll with the nose gear steering selected to low. A line speed check was performed at 100 knots indicated airspeed (KIAS) and before the airplane had reached the arresting cable, located about 1,440 ft from the approach end of runway 14R. Everything was acceptable at that time. The takeoff roll continued and at about 125 KIAS, which was just after the airplane had crossed the arresting cable, the pilot reported, “there was this huge swerve to the left and it was an instantaneous swerve.” He applied full right rudder input and tapped the right brake, but without effect. The airplane drifted towards the left edge of the runway and the pilot applied aft elevator input, became airborne and flew in ground effect. The airplane accelerated and climbed while remaining in the same configuration (flaps and slats full, gear down). The pilot flew south over the water where he orbited numerous times to burn fuel and determine the condition of the airplane. The second airplane had aborted its flight during the takeoff roll.

While orbiting over the water, the front- and rear-seat pilots reviewed the applicable emergency procedure checklists and discussed possible system failures, such as blown tires, brake and anti-skid failures, NWS failures, and loss of control. Nearby pilots provided a visual check of the landing gear and tires. The accident pilots’ operations base also provided input into the most likely cause of the problem. After considering all the possibilities, the consensus was that there was an issue with the left main landing gear. The pilot also stated that he was prepared to turn off the NWS if the airplane started veering after touchdown.

After burning fuel and coordinating with air traffic control, the pilot returned to PAM to land on the right side of runway 14L. He touched down near the right edge of the runway. When the main landing gear contacted the runway, the rear-seat pilot deployed the airframe drag chute. The pilot put the nose down as soon as he landed and felt a significant pull to the left occurring soon after he relaxed left-wing-up control input. He applied full right rudder and brake but without effect. He did not turn off the NWS because of the rapid sequence of events. The airplane departed the runway onto the grass infield and the nosewheel landing gear collapsed. The rear-seat pilot initiated an unannounced ejection; the rear seat ejected successfully, but the front seat did not. The airplane continued to skid across the grass infield and then impacted a taxiway. When the airplane came to rest, the pilot secured the engine but was unable to get out of the airplane. Both occupants were rescued by responding emergency personnel and both had incurred serious injuries. AIRCRAFT INFORMATIONAccording to ATAC’s Mirage F1 flight manual, the airplane was equipped with electro-hydraulic nosewheel steering (NWS) that was commanded by the rudder pedals and available whenever a microswitch on the nose strut (weight-on-wheels switch) was compressed.

The flight manual had a procedure for the symptom, “Aircraft Swerves During Taxi.” The action items directed the pilot to verify that the NWS caution light was out. If it was out, it specified to check the rudder trim, and if required, turn off the anti-slip switch. If that was unsuccessful, the pilot was to turn off the NWS switch.

The airplane was equipped with ejection seats at both positions, capable of ejection at all altitudes and at all speeds between 0 and 620 knots. A sequence selector in the front cockpit was used to select the ejection sequence for either solo or dual flight operations In the DUAL position, both seats were connected for ejection by the ballistic manifold to the disconnecting block/disconnect unit to the airframe connection (Command Selector valve) at the front seat or Connector Unit (rear seat). If the rear cockpit initiated the ejection sequence, the rear seat ejected immediately, and the gas from the rear connector unit flowed to the front seat disconnect unit to begin the ejection sequence. A built-in 0.5 second delay occurred before the front seat ejection was initiated. Seat ejection was controlled by pulling the firing handle on the front of the seat bucket between the occupant’s thighs.

At the time of the accident, neither the flight manual nor the operator had any limitation preventing operation of the airplane from a runway equipped with an aircraft arresting system. AIRPORT INFORMATIONAccording to ATAC’s Mirage F1 flight manual, the airplane was equipped with electro-hydraulic nosewheel steering (NWS) that was commanded by the rudder pedals and available whenever a microswitch on the nose strut (weight-on-wheels switch) was compressed.

The flight manual had a procedure for the symptom, “Aircraft Swerves During Taxi.” The action items directed the pilot to verify that the NWS caution light was out. If it was out, it specified to check the rudder trim, and if required, turn off the anti-slip switch. If that was unsuccessful, the pilot was to turn off the NWS switch.

The airplane was equipped with ejection seats at both positions, capable of ejection at all altitudes and at all speeds between 0 and 620 knots. A sequence selector in the front cockpit was used to select the ejection sequence for either solo or dual flight operations In the DUAL position, both seats were connected for ejection by the ballistic manifold to the disconnecting block/disconnect unit to the airframe connection (Command Selector valve) at the front seat or Connector Unit (rear seat). If the rear cockpit initiated the ejection sequence, the rear seat ejected immediately, and the gas from the rear connector unit flowed to the front seat disconnect unit to begin the ejection sequence. A built-in 0.5 second delay occurred before the front seat ejection was initiated. Seat ejection was controlled by pulling the firing handle on the front of the seat bucket between the occupant’s thighs.

At the time of the accident, neither the flight manual nor the operator had any limitation preventing operation of the airplane from a runway equipped with an aircraft arresting system. WRECKAGE AND IMPACT INFORMATIONExamination of runway 14R was performed by representatives of the Federal Aviation Administration (FAA), the operator of the airplane, and the ejection seat manufacturer. Markings from the main and nose landing gear tires were first identified about 580 ft past the arresting system closest to the approach end of the runway. The markings were initially centered on the left side of the runway consistent with the takeoff position and appeared to swerve to the left. The marks from the main landing gear tires continued to the point where the airplane became airborne. At that location the left main landing gear was off the left side of the paved surface and the right main landing gear was left of the runway edge marking but still on paved surface. Further examination of the runway revealed damage to one runway edge light associated with the tire track from the right main landing gear.

Following the accident, runway 14R was swept and the sweeper truck contained a component that was determined to be the missing anti-skid connector from the right main landing gear of the accident airplane.

Examination of the landing runway, 14L, and the ground path revealed it could not be determined by physical evidence where the airplane touched down; however, based on video evidence the airplane appeared to touch down near the intersection of taxiway Delta, or about 7,000 ft before the departure end of the runway. Inspection of the runway revealed light residue from the nose landing gear tires and the marks from the nose landing gear tires showed a veer to the left. The marks from the nose and then main landing gear tires continued off the left side of the runway with the marks from the nose tires closer to the left main consistent with the airplane being yawed to the left. The marks from the tires continued onto the grass that was relatively flat except one area described as a “ramp,” or about an 18-inch rise in terrain. Immediately before the “ramp” marks in the grass were noted but no marks were noted for about 29 ft after the ramp. Either on the “ramp” or about 10 ft after the “ramp,” a section of the airplane’s floorboard or pressure bulkhead was found, while about 282 ft after the “ramp” large pieces of rear canopy were noted. The marks then continue across grass adjacent to the runway and also across taxiway Foxtrot then onto grass, where the airplane came to rest upright with the nose landing gear collapsed about 5,857 ft and 122° from the approach end of runway 14L.

Examination of the airplane where it came to rest revealed the nose landing gear was collapsed aft and the anti-skid connector of the right main landing gear was separated. The drag chute was deployed and the air brakes, flaps, and slats were fully extended. The drag chute did not display any signs of ...