A KC-135’s autopilot turned on or off without prompting

| September 27, 2023

Flight crews on a KC-135 reported, back in 2021, that the autopilot turned on or off without human interaction in the middle of a flight. One of the unauthorized autopilot commands turned the airplane towards the ground. The aircraft was flying under 3,000 feet when one of these automatic actions occurred.

From the Air Force Times:

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.

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.

The Air Force initially said a faulty power supply caused the autopilot to malfunction, but later attributed the problem to an error in the program’s code, defense technology publication The War Zone reported last year. Collins Aerospace, which designed the software, was expected to begin testing fixes in April 2022.

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.

Block 45 was installed on 272 aircraft as of March 2023, according to the service’s budget documents. It is slated for use on 329 airframes based on the C-135 — all but a few dozen of which are KC-135s — plus 19 pilot simulators and five cockpit simulators.

The Air Force Times provides additional information here.

Category: Air Force

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Don’t trust a computer.
They are programmed by humans, who are fallible and ignorant.

written as a retired programmer


More like “don’t trust code written by a diversity hire at the lowest bidder”




This is why it makes it so easy to identify Trump supporters.


One may deplore “diversity hires” yet not support Trump.


Absolutely, but making such an association without any evidence whatsoever calls for a particular kind of thinking.


“making such an association without any evidence whatsoever”

That kind of thinking is obviously not particular to Trump supporters.


Where’s commisar…


Which astronaut, when asked what he was thinking before the rocket lit said, and I paraphrase, “This thing was built by low bidder”.

These companies don’t care about losing money up front, they’ll make it up on what ISN’T covered by “warranty” and later on support parts.

It’s not like Napa has what you need.


That’s even worse. ‘Bout like hiring a high school kid who’s only built things in Minecraft.

But even if you have top-flight programmers don’t trust the software with your life. They cannot program for the rare unexpected situation.

Green Thumb

Or a contract performed by All-Points Logistics.


I should add that autopilot and other such systems should always have a cast-iron override available.


Intermittent problems can be a cast-iron bitch to track down. I’d write this up as a Part I deficiency and recommend halting flight test until the issue was resolved.


Where’s that old meme, joke whatever where the pilots do post flight write up and the mechanics leave comments to show it was looked at.

Pilot complaint…The plane does xxx at xxx altitude
Mech says… can’t duplicate at ground level

Pilor… plane flies funny
Mech… told plane to straighten up and fly right..

You get the idea.


In addition to the standard 781 writeups some units I’ve been in kept history logs with interesting tidbits of info encountered. When we were going to take a bird on the road for an extended period I always reviewed these. Now crew dawgs being crew dawgs there may be some humor inserted to keep folks on there toes.

My favorite writeup of all time was this… Aircraft lands hard and left of centerline.


So recalibrate the centerline.




A couple of clicks to the right on the autopilot should fix that.


You want it fast, good or cheap?
Pick two.


Bring the mechanic with– see, it’s doing that again!


After Program Office review my deficiency would be downgraded to a Part II with the recommendation the pilots pay strict attention to their altitude when the autopilot is engaged.

President Elect Toxic Deplorable Racist SAH Neande

I have not ever worked around aircraft, but being an electronic repairer, finding an “intermittent” is a pain in the ass.
Sometimes it can be tracked down to a loose (intermittent) ground.
Sometimes to corrosion eating (almost all the way) through a trace.
Sometimes to corrosion coating a connector pin/socket. Sometimes to dissimilar metals on a cable pin & socket (creates a galvanic “high resistance short”)

I always enjoyed the finger-pointing and chest-thumping arguments between the mechanical engineers and the computer engineers on who owned the current problem.


The whole while those who have to fix the problem wait to see who wins the argument.

President Elect Toxic Deplorable Racist SAH Neande

Those who have to fix (repair) the problem don’t care who wins the argument, they just go ahead and fix (repair) the problem. Leave it to the engi-queers to fix (redesign) the problem.


I’m sorry Dave …
but the problem has always been human error.

Mike B

We had a MC-130E that would porpoise while on auto pilot. It would fly level for a while, then start to porpoise, then after awhile level back off.

I learned this in Oct 2001, as I was self loading baggage, and was asleep in a hammock stretched across the ramp over the baggage pallet. I had to grab the cargo netting on the baggage pallet, to stop the hammock from swinging. I remember thinking to myself what in the hell are the pilots doing? And, are they that bored up there?

Talked to one of the Load Master’s afterwards, he explained what it was and said it was a known issue with this tail number, and that even depot couldn’t figure it out. She eventually went to the Boneyard without the issue ever being solved.

My dad was Aircraft Maintenance on fighters during his career. They had a F-4 that the pilots would write-up for the gun being out of alignment. They would bore sight it and clear the writeup. After several write-ups, it was discovered that the nose of the aircraft was warped.

USAF Retired


My son works at a maintenance facility for jets, and one customer complained about their plane porpoiseing. They finally tracked it down to the aft luggage bay being overloaded. They spread the weight around, end of problem.


Showed this to someone who ostensibly knows something about this…posting here for thoughts, clarification, derision, whatever is appropriate.

In essence, something about the chips being manufactured in China and having glitches, backdoors, something built in? Something so minor that it appears irrelevant, like a ghost/shadow in the machine but is a hook which will snare later commands or programming? It was explained to me in Star Trek terms – like telling the Borg to “sleep”.

Seeing that I know less than nothing, what say all you who do know more than plugging and unplugging the cable box when it acts up?


It is a known problem that “backdoors” are frequently inserted into hardware systems as well as software.
Occasionally the news will have a report of some three letter agency bullying manufacturers and developers into installing them so they can spy on users- for catching criminals of course. /s
China has been known to do that, too.
I don’t know what is in the planes system(s) but the possibility is real.


My thoughts exactly, OAM. Not all Sleeper Agents are human and you can put all sorts of hidden commands in chips and or the code they feed on. And pulling all of the manufacturing of these components back home would only delay the human agents gaining access to the nefarious person that would sell out the country’s security for a few bars of gold plated latinum. Then, too, it could be a simple as a bad connection, somewhere, in the literally miles of circuitry in a modern day aircraft.

Wondering if Collins Aerospace used to be Collins International Service Company (CISCO)? If so, I have some stories about them…and their purchasing agents…and QC troops.


That “low tire pressure” warning drove me nuts until I finally
put a piece of tape over the light.


Did’ja check the spare?


That’s what you get when your autopilot is HAL9000.

jeff LPH 3 63-66

How come aircraft arn’t fitted with blowup dolls like I saw in Airplane that could rectal the situation.


Sky penises and all that. Shwiiiinnnggg.


More flyin’ hijinx… not involving equipment (of, at least, not the airplane’s anyway):

Skivvy Stacker

AI is making it’s move already.