Air Force KC-135 Stratotanker pilots are inching closer to normal operations after incremental software fixes to the tanker’s glitchy autopilot have led the service to ease flight restrictions on the jets.
Airmen at the moment are allowed to fly KC-135s with the Block 45 software upgrade — which incorporates the autopilot in query — at altitudes below 10,000 feet, Air Mobility Command boss Gen. Mike Minihan said Sept. 11.
“We’re just now bringing the operational capability of the autopilot back up. I’ve got confidence within the fixes,” he told Air Force Times on the Air and Space Forces Association’s annual Air, Space and Cyber Conference outside Washington.
It’s the most recent step toward resolving a potentially dangerous problem that began greater than two years ago.
In early 2021, KC-135 crews began reporting incidents of the autopilot turning on or off, unprompted, during flight. That has caused the jets to unexpectedly tilt toward the bottom or pitch upward, including in not less than one instance when the aircraft was inside 3,000 feet of the bottom.
The difficulty has occurred five times since May 2021, Air Force spokesperson 1st Lt. James Stewart said. All but one among those instances happened between May 2021 and May 2022.
The Air Force initially said a faulty power supply caused the autopilot to malfunction, but later attributed the issue to an error in this system’s code, defense technology publication The War Zone reported last yr. Collins Aerospace, which designed the software, was expected to start testing fixes in April 2022.
The Air Force remains to be rolling out the software patch across its fleet of greater than 300 KC-135s, Stewart said. The service didn’t answer what number of KC-135s are flying the unique Block 45 software and what number of have the updated version.
Block 45 was installed on 272 aircraft as of March 2023, in response to the service’s budget documents. It’s slated to be used on 329 airframes based on the C-135 — all but a couple of dozen of that are KC-135s — plus 19 pilot simulators and five cockpit simulators.
Data collected by the Air Force to tell its Sept. 11 decision to alter the flight restriction showed the autopilot had worked appropriately over greater than 10,000 hours in flight, Stewart said.
Now a brand new policy is in place to maintain troops secure while they start to make use of the updated autopilot on their day by day missions. Airmen can’t activate the autopilot when flying when flying in bad weather or at night at an altitude of lower than 2,000 feet.
Allowing the autopilot above 10,000 feet gave airmen more time to react in case something went unsuitable. Lowering that bar indicates the service has enough confidence within the fixes to tackle more risk, without eliminating precautions altogether.
“We’ll construct trust in those fixes with these restrictions in,” Minihan said. “Once we’ve got trust, then we’ll take a look at the complete capability of the autopilot.”
He believes the Air Force will log out on unfettered use of the autopilot inside the subsequent yr.
“My biggest concern is for the security of our airmen, at all times, and I don’t wish to rush that,” he said. “The restrictions were great in its use, but they were secure. We’ve got to be cautious moving forward [and] allow the expert airmen that fly, fix and support it to do what they do best.”
Stewart said no aircraft have been damaged, or airmen injured, due to autopilot failures.
“AMC trusts KC-135 aircrew members to securely perform their mission,” he said.
Rachel Cohen joined Air Force Times as senior reporter in March 2021. Her work has appeared in Air Force Magazine, Inside Defense, Inside Health Policy, the Frederick News-Post (Md.), the Washington Post, and others.