Safety Publications/Articles

Professionally Speaking

Trapping errors: A scheme for avoiding accidents

There is a safety concept some call "trapping errors" that can often make sense to use. We all make errors, even when flying. The goal is to set up systems that "trap the error" before the error causes an accident.

For example, it is possible to forget to lower the landing gear before a landing. That error can and will cause an accident upon landing. Our goal is to trap that error before we land.

We do have an extensive system set up and in use to trap that error. The first trap is the "gear down" indicator lights. A rudimentary prelanding checklist will include something along the line of "gear down and locked." If we do that one simple thing, the warning lights will let us know if the gear is not down and locked. Voilà, our system "trapped" the error.

But what if we skip or miss those warning lights?

Then we have a back-up trap. As we slow for the landing, at some point there will be some combination of blinking light(s) and honking horn to tell us the gear is not down. This is the second trap.

But what if we miss the horn? In a perfect world, the tower--providing our third trap--will warn us that the gear seems to be up. Being sharp pilots, we will then say, "Thanks, tower, we'll recycle the gear." We put it that way to imply that we already put the gear down and the fault must be with the equipment, and certainly not with us. Either way, the error is trapped, the gear is extended, and there is no accident.

Could anyone land with the gear up after being warned by the tower? Yes, even that trap can fail. There is the pilot of legend who told the tower, "I can't hear you, I've got this horn honking in my ear." Then he landed gear up.

Note that if you are a two-pilot crew, another trap is that one of the pilots notices the error at some point and corrects the problem.

In spite of all these traps, it is possible to land with the gear up. Here's a true story: A fellow was flying a young lady into a big city. She was suitably impressed and asked many questions. Finally, he told her, politely but firmly, that she'd have "to be quiet now until we get on the ground. There's lots of traffic here and I have to pay attention." Sure enough, he landed with the gear up. Afterward the young lady told a friend, "During the entire landing I was dying to ask him about the blinking lights and the horn honking, but he had said be quiet, so I didn't ask."

Your entire checklist is full of traps for errors. As CFIs you have the opportunity and responsibility to ingrain this concept into students' heads and routines.

Ralph Hood, an aviation speaker and writer, has been flying since 1971 and has more than 3,000 hours of flight time. He is a multiengine commercial pilot with an instrument rating. Visit his Web site.

By Ralph Hood

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