QRF-4C T/N 69-0384, TYNDALL AIR FORCE BASE, FLORIDA 17 JULY 2013 On 17 July 2013, at approximately 13:23 Zulu (Z) time, a QRF-4C Phantom II unmanned aircraft, tail number (T/N) 69-0384, operating in autopilot, impacted the ground on the south end of runway 18 at Tyndall Air Force Base (AFB), Florida (FL), approximately 8 seconds after takeoff. The mishap aircraft (MA) was assigned to the 82d Aerial Targets Squadron (82 ATRS), 53d Weapons Evaluation Group (53 WEG), 53d Wing (53 WG), Tyndall AFB, FL. The MA, an infrared flare- dispensing pod (Mongoose 4 Pod), and 120 flares were destroyed on impact. The drone runway and its barrier also incurred significant damage and required repair. The total damage to United States (U.S.) Government property was assessed to be $4,564,536.00. There were no injuries or damage to other government or to civilian property sustained as a result of this mishap. The Mishap Controller (MC) released the brakes on the MA at 13:22:47Z and selected the Automatic Takeoff (ATO) mode. The MC provided launch recommendations to the Drone Mission Commander (DMC) and was responsible for controlling the MA through all phases of flight. The MA began its takeoff role, increased speed to 165 knots, and lifted off the ground as the landing gear and flaps were raised. The MA lifted off the ground at 13:23:08Z and immediately demonstrated pitch issues. Upon takeoff, the MA pitched up and initially achieved its normal 12 degrees above the horizon attitude. Approximately two seconds later, the MA pitched down approximately five degrees, then rapidly pitched up to 28 degrees above the horizon—which exceeded the limits of the MA. After identifying the inappropriate pitch change, the MC determined the MA was airborne and within approximately a half second determined the appropriate emergency checklist response. At approximately the same time, the Gulf Range Drone Control Station (GRDCS) responsible for controlling the aircraft during ATO, detected a bad stabilator condition and displayed it on the MC’s display. The stabilator, commonly known as an all-moving tail, provides longitudinal stability, control and stick requirements that are normally performed by a horizontal stabilizer. The MC executed the required emergency checklist items to recover the MA, using a series of push button commands beginning with the ATO and followed by the All Attitude Recovery (AAR) command. The MA subsequently entered a stall, pitched down 33 degrees and impacted the ground at 13:23:17Z. The entire flight lasted approximately 8 seconds. The Accident Investigation Board (AIB) President found, by clear and convincing evidence, that the cause of this mishap was a defective pitch rate portion of the Attitude Heading Reference System (AHRS), otherwise known as the aircraft system that controls the up and down movement of the MA. The AHRS was responsible for the movement of the MA in all three axes—which include pitch, roll and yaw. The defective AHRS was destroyed in the crash; however, the AIB was able to determine, using the data from the GRDCS, that the AHRS sent erroneous inputs on the horizontal pitch of the MA to the Primary Automatic Flight Control Computer (PAFCC). These erroneous inputs caused the MA to pitch up and down rapidly and to enter a 28 degrees above the horizon attitude. This exceeded the stall threshold and subsequently pitched the MA down 33 degrees—causing the MA to impact the ground.