SOFTWARE CAUSED SPY PLANE CRASH.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - A software glitch is being blamed for the Dec. 6 runway crash at Edwards that caused $5.3 million damage to an unmanned spy plane.

After the $45 million Global Hawk spy plane had finished a successful flight test and was at a full stop, the software problem caused the aircraft to accelerate to about 175 mph until it veered off the base's main runway, according to an Air Force report.

``Once the erroneous taxi speed was introduced, the mission planning and validation processes failed to recognize or correct the error,'' said Col. James R. Heald, accident investigation board president. ``The board concluded that once the air vehicle autonomously executed the taxi portion of the mission plan, there was insufficient time for the test team to stop Global Hawk from taxiing off the runway.''

At the same time the Air Force was releasing information about the incident, the service also issued news releases highlighting program successes. Those successes include an April 14-15 flight in which a Global Hawk aircraft set an endurance record for jet-powered, unmanned aircraft by staying aloft for more than 31 hours.

On April 20, a Global Hawk flew from Edwards to Eglin Air Force Base in Florida, conducting demonstrations for the U.S. Coast Guard of its potential anti-drug smuggling surveillance capabilities.

The same aircraft will be flown to Europe for NATO military exercises in May.

The runway crash was the second incident for the Global Hawk program. On March 29, 1999, a Global Hawk crashed because it inadvertently received a flight-termination signal from a Nevada test range. The aircraft was flying near the China Lake Naval Weapons Center when it received the termination signal from Nellis Air Force Base.

The radio signal caused the plane to go into a flight termination maneuver: a preprogrammed rolling, vertical descent from an altitude of 41,000 feet.

Nellis was conducting tests of a radio transmitter on the same frequency as the Global Hawk's flight termination frequency. The tests were part of an effort to gear up for a military exercise in which Global Hawk was to be one of the participating aircraft.

Global Hawk is being developed by Northrop Grumman's Ryan Aeronautical. Shorter than an F-16 but with the wingspan of a Boeing 737, the Global Hawk is designed to fly as high as 65,000 feet and stay there for up to 42 hours at a time. The aircraft will be able to survey 40,000 square miles, an area the size of Illinois.

Northrop announced in October that it would shift the assembly site of the Global Hawk aircraft from San Diego to Palmdale. The aircraft are being flight-tested at Edwards.