A combination of bad navigational software and timing led to the November crash of the MQ-9 Reaper drone crash into Lake Ontario, the Air Force colonel who investigated the crash said.
“It was kind of a perfect storm that this thing happened,” said Col. Dana A. Hessheimer, who oversaw an Air Force Accident Investigation Board whose 21-page report about the incident was released July 1.
Within two days of the Nov. 12 incident, he said, the Air Force issued a servicewide notice to remedy the unspecified software problem.
“They corrected that right away,” Col. Hessheimer said, later comparing the notice to the safety recalls of automaker General Motors.
The colonel, who leads the 163rd Reconnaissance Wing, March Air Reserve Base, Calif., spoke with media about the crash in a conference call Thursday afternoon.
The Reaper drone from the 174th Attack Wing, Syracuse, crashed about 12 miles from the lake’s eastern shore and 35 miles from Fort Drum’s Wheeler-Sack Army Airfield, where it took off.
During the flight, two of the aircraft’s three navigational systems failed. Col. Hessheimer said as the aircraft’s computer switched to the third unit, it set faulty variables for its autopilot, giving it incorrect information about its pitch, roll and location.
At that time, a human operator, not knowing of the on-board computer errors, ordered the autopilot to turn right.
“If he would’ve waited another 20 seconds, it would’ve came back,” Col. Hessheimer said.
The navigational software failures sent the craft in a downward spiral at 5,000 feet per minute, the report said.
“I’m sure it was going fairly fast,” Col. Hessheimer said. “If you remember ‘Top Gun’ when Goose died, that’s what the plane was doing.”
The software inside the Honeywell Aerospace navigational unit failed twice in the weeks before the crash, but had been replaced before the Nov. 12 incident. The Air Force notice after the crash resolved the issue, Col. Hessheimer said. He said he could not specify which software failed, citing security concerns.
The 174th Attack Wing grounded its remaining drones for several weeks after the crash, but they resumed flying at the end of November.
Few pieces were recovered from the aircraft, Col. Hessheimer said, primarily composite pieces light enough to float. The Air Force estimated the value of the aircraft at $10.6 million.
Following a recent Washington Post report that counted 418 crashes for unmanned aircraft from September 2001 to the end of 2013, Col. Hessheimer said the Reaper aircraft was safer than F-16s, based on the number of crashes per 100,000 hours of flying time.
He said that he had flown the aircraft since 2007. Though he said new technologies can scare people, Col. Hessheimer said, “they should feel completely safe about remotely piloted aircraft flying above them.”