2015 Los Llanos Air Base crash

Investigation

Initial findings were that a technical fault developed on board the F-16 during take-off, and the two crew members had tried to eject. Aviation analyst Sean Maffett told the BBC News Channel that it was "difficult to imagine how the accident had occurred, because the runway where the aircraft was taking off was about 1,000 ft (305m) away from where the crash apparently took place."

Six months later, in July, investigators determined that a 'loose checklist' may have caused the aircraft to crash. According to a safety investigation board report by the French Defense Ministry, a manual knob in the cockpit that controlled the trim tab on the tail rudder was inadvertently turned all the way to the right, causing the plane to roll uncontrollably to the right seconds after takeoff. Some time before the F-16D took off, "the yaw trim was set to the maximum right deflection, drastically affecting the aerodynamics of the aircraft during takeoff," the report said.

Though there are safety guards mounted on either side of the yaw trim switch to prevent unintentionally moving it, investigators believe one of three loose flight checklists in the cockpit must have jammed the knob all the way to the right. The checklists were to be placed in the cockpit's stowage compartment, but the lead pilot stored his flight bag in the compartment instead, the report said.

Physical tests performed by the safety investigation board members determined that while it's difficult to inadvertently turn the knob, an object such as a checklist - they are usually laminated - pushed between the yaw knob and the safety guard "can cause the same roll and yaw trim movements as recorded" in the aircraft.

The Hellenic Air Force jet crashed about 7.8 seconds after takeoff, as the askew trim tab forced the plane to bank hard to the right and pulled its nose down. The lead pilot's "left control stick inputs were insufficient to cease the right roll," the report said.

The lead pilot "had to react in the unforgiving altitude of no more than 6 feet, the fact that the landing gear was left in the down position can be considered as a clear indication of the surprising nature of the problem."