Air Force KC-135 Stratotanker pilots are inching closer to normal operations after incremental software fixes to the tanker\u2019s glitchy autopilot have led the service to ease flight restrictions on the jets.<\/p>\n\n\n\n
Airmen are now allowed to fly KC-135s with the Block 45 software upgrade \u2014 which includes the autopilot in question \u2014 at altitudes below 10,000 feet, Air Mobility Command boss Gen. Mike Minihan said Sept. 11.<\/p>\n\n\n\n
\u201cWe\u2019re just now bringing the operational capability of the autopilot back up. I\u2019ve got confidence in the fixes,\u201d he told Air Force Times at the Air and Space Forces Association\u2019s annual Air, Space and Cyber Conference outside Washington.<\/p>\n\n\n\n
It\u2019s the latest step toward resolving a potentially dangerous problem that began more than two years ago.<\/p>\n\n\n\n
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 ground or pitch upward, including in at least one instance when the aircraft was within 3,000 feet of the ground.<\/p>\n\n\n\n
The issue has occurred five times since May 2021, Air Force spokesperson 1st Lt. James Stewart said. All but one of those instances happened between May 2021 and May 2022.<\/p>\n\n\n\n
The Air Force initially said a faulty power supply<\/a> caused the autopilot to malfunction, but later attributed the problem to an error in the program\u2019s code, defense technology publication The War Zone reported last year<\/a>. Collins Aerospace, which designed the software, was expected to begin testing fixes in April 2022.<\/p>\n\n\n\n The Air Force is still rolling out the software patch across its fleet of more than 300 KC-135s, Stewart said. The service did not answer how many KC-135s are flying the original Block 45 software and how many have the updated version.<\/p>\n\n\n\n Block 45 was installed on 272 aircraft as of March 2023, according to the service\u2019s budget documents. It is slated for use on 329 airframes based on the C-135 \u2014 all but a few dozen of which are KC-135s \u2014 plus 19 pilot simulators and five cockpit simulators.<\/p>\n\n\n\n Data collected by the Air Force to inform its Sept. 11 decision to change the flight restriction showed the autopilot had worked correctly over more than 10,000 hours in flight, Stewart said.<\/p>\n\n\n\n