Consider another example. There was a case where the pilots had set the automatic air pressure regulator to "manual". As they climbed past 10,000 feet, a warning horn sounded because the cabin air pressure was too low. The horn sounded similar to another horn, and the pilots worked the other horn problem.
Then, they lost consciousness from lack of oxygen and crashed, killing all aboard.
This is not a self-evident user interface. A better one would be to change the beep of the warning horn to a voice: "alert: air pressure too low". Now the pilots save precious seconds figuring out what's wrong and how to fix it. The horning could be even better: "alert: air pressure too low. Don oxygen mask".
With the landing gear lever, maybe a pilot in training needs to be told what it does once. But he'd never have to be told again.
Then, they lost consciousness from lack of oxygen and crashed, killing all aboard.
This is not a self-evident user interface. A better one would be to change the beep of the warning horn to a voice: "alert: air pressure too low". Now the pilots save precious seconds figuring out what's wrong and how to fix it. The horning could be even better: "alert: air pressure too low. Don oxygen mask".
With the landing gear lever, maybe a pilot in training needs to be told what it does once. But he'd never have to be told again.