It turns out that pilots have been mostly perfect. Trim failures do happen, but in nearly all situations, the crew reacts correctly and the flight continues to a safe landing. Of course there have been fatal accidents caused by trim failures, and not just a few, but they are small in number compared to the total number of flights.
But at the jet level, flying has become so safe, that even a small number of accidents deemed acceptable even 25 years ago, is no longer tolerable. And electronic advances make it possible to include at least triple-redundant monitoring and sensing in critical flight control systems. Fly-by-wire (FBW) control systems—which all newer designed larger jets employ—use triple redundant computers and sensors to operate all flight controls, including trim. Pilots’ movement of the cockpit controls are the equivalent of moving the mouse on your desktop computer.
If you believe that the public has more confidence in a well-trained and experienced human pilot than in a FBW automated control system, try explaining the three-second recognition time. Once they understand that human pilots have three seconds to recognize pending disaster, and take the proper action to prevent a crash every time without fail, the public wants the multiple backups of FBW computers.
If you don’t believe me, read and listen to coverage of the 737 Max situation. The very idea that human pilots must be relied on to disable a malfunctioning critical flight control system stuns the media and, according to polls, the flying public. It doesn’t matter that the vast fleet of 737s—the most common jet airliner in the world—flies on with a pitch trim system that can run away, and that pilots must recognize and respond correctly to prevent a crash. That fact hasn’t been brought to public attention. The three-second recognition time is never mentioned, or even understood. If it was, the media and public would be as alarmed as they are about the MCAS system on the Max. They trust pilots, but unlike many of us who are pilots, the public knows there is no perfect pilot.
