Board Finds High Taxi Speed
Caused Global Hawk Crash
04/25/00 11:50:38 AM U.S. EDT
The Air Force Mishap Investigation Board examining the Dec. 6 accident involving a Global Hawk unmanned aerial vehicle has determined that taxiing at an excessive ground speed of 155 kt. caused the mishap.
The No. 3 Global Hawk veered off the main runway at Edwards AFB, Calif., at 4:17 p.m. PST, following a successful mission and full-stop landing. The UAV then accelerated to an excessive taxi speed and veered off the main runway, collapsing its nose gear and damaging its sensor suite.
"The primary cause of this mishap was the execution of a commanded, taxi ground-speed of 155 knots," said Col. James R. Heald, Accident Investigation Board president. "The excessive ground speed was introduced by a combination of known software problems between the vehicle's Air Force Mission Support System core mission planning system and its aircraft/weapon/electronics-specific mission planning system."
The UAV’s mission planning and validation processes failed to recognize the error, Heald explained. The test team did not have enough time to stop the Global Hawk before it ran off the runway.
The damage to Global Hawk No. 3, including the sensor package, was estimated at $5.3 million, Air Force officials said