Engineering MISTAKE Leads to Near Catastrophe! The Incredible Story of Republic Airways 4439

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I love when he starts talking about what the pilots were thinking in the moment because that means they survived

Electronics R&D taught me that if you replace a part more than once and an intermittent fault persists, look for the problem elsewhere. They were going for an easy fix, not diagnosing the actual problem.

It always amazes when he goes on about the whole situation, and then states it all happend within 5 minutes. Makes you realize how fast it all happens.

I'm a Republic pilot and we have definitely changed our procedures and memory items due to this incident. Runaway trim is extremely difficult to catch and react to in time, it took me failing in the sim to realize where I needed to look to catch it and not rely on the 3 second active warning announcement to catch it. This is one of the scarier failures to run across that doesn't include pieces coming off the airplane.

I am a seaplane pilot at my job, and the aeroplanes we use are steered on the water using differential thrust and reverse from the two engines. Manoeuvring is very easy from the captain's position using two power levers on the cockpit ceiling. Occasionally, the engineers want us to park the plane with the starboard against the dock because it makes it easier to work on engine #2. One time I thought it might be easier to do this from the first officer's side, so I could see the dock more easily from there. I was quite mistaken. It turns out that my left hand has no idea how to steer the plane using the power levers. It is all muscle memory. There is no way to use just your knowledge to make your hands obey. The plane was extremely difficult to control until I got back into the seat I was accustomed to. Another time I was doing maintenance on my sailboat and installed the ropes that control the rudder backwards, resulting in reversed steering. It's a massively annoying job so I decided to leave it and go sailing anyway. I thought I could use my brain and remember the steering was reversed. Well, even knowing about the problem didn't help. The minute I left the dock, I was in trouble. I barely made it back without tipping the boat over or hitting something. Both those instances demonstrated to me how powerful "muscle memory" is, and how nearly impossible it is to work against it.

I worked for Republic as a mechanic during this. Afterwards, every plane that came through had a required inspection to inspect the safety wire and the harness on the yokes. We also complied with that service bulletin by installing a bracket so the switch could not be installed upside down.

This quality of content is something one would usually pay for to watch on Netflix or any platform, but you give it for free. Thanks Petter, what an inspiration!

It always warms my heart when a history like this end up as the pilots landed safely.

It's absolutely insane that the maintenance techs were like oh well this sticker doesn't work, there is absolutely nothing else we can put here to remind the pilot that it's out of service. A small piece of masking tape with an X on it could have prevented this entire situation. The laziness is unreal.

As someone who has worked in IT, there have been times when I SHOULD have known what to do but because I thought I knew what the problem was I instead did 20 things BEFORE I did the thing I should have done. And I wasn't even flying a plane and worried about dying.

I'm currently in school to become an Aeronautics Electronics Technician and I actually just did an exercise like that today, unintentionally. Ended up looping wires inverted and when I set the switch to on, it was off and vice versa. Shocked the hell out of myself trying to take it apart thinking it was off.

At a tech museum near me, they have a bike with super wheels that is rigged to lean the wrong way during a turn. Trying to ride this bike is one of the most confusing experiences I’ve ever had. The feeling of disconnect between your conscious intentions and what your muscle memory is making you do is unreal.

I'm no pilot, but after watching 100's of aircraft incident reviews, you explained the trim system better than anybody, which gave such a clear understanding of what lead to this. Bravo Petter, as always.

I would definitely stick that INOP sticker on the trim switches. It doesn't need to last the flight, just long enough for the captain to register that it isn't working properly.

Fun fact, the accelerator pedal in your car has dual redundant circuits like this switch. (Obviously I'm only referring to modern vehicles with drive-by-wire throttle control.) In the event of a mismatch, for instance because of a broken wire as happened to one of my vehicles, the ECU will switch into a severely limited "Limp Mode" where your engine RPM is limited to 3000, and max throttle input is limited to like 25%. Takes minutes to achieve freeway speed, lol. This is to make any runaway situations easy to control with the brakes, and to protect the engine if it erroneously reads a max throttle input when the vehicle is in neutral (3000 RPM won't destroy a gasoline engine). I thought this was a cool set of safety redundancies, developed by some very smart engineers.

I had a similar problem happen in a Beech Duchess, back in 2005. The mechanics cabled up the trim in the opposite sense to how it was meant to work. When, I trimmed the opposite happened to what I expected, so I stopped trimming and returned to land. Rather than being sorry for the mistake the maintenance guys blamed me, saying that the problem was easy to work out and I should have just trimmed in the opposite sense. Looking back, this was BS and they were lucky they got away with it.

As an electrical engineer, upside down switch was the first thing that came to my mind as soon as I found out it was taken out. However I can easily see how it could not be the on less technical person's mind. And even I wouldn't exactly be eager to try to push the switch in the direction that is supposed to make the situation worse - both intuitively and consciously, as that kind of behavior can arise from any number of failures, and it could indeed make the situation much worse. Kudos to everyone involved for handling the situation.

There are no more frightening words than, "it was a perfect day for flying."

This one was such a rollercoaster. I was so scared listening to this one, I don’t blame the captain for going back to the trim switch, the muscle memory and training is too strong. They did such a good job managing it, I was terrified they were going to crash.