Training Tip: Slips and mistakes

As the yarn had it, a flight instructor, at his wits’ end to get a particularly hesitant student to take charge of the aircraft, disconnects his control stick, taps his student on the shoulder to get his attention, and then flips the stick overboard.

The anecdote’s dubious authenticity aside, obviously the student’s action was erroneous. Was it a slip or a mistake?

This isn’t an idle debate about semantics. Because the teaching (and learning) process is heavily dependent on the analysis and correction of errors, it’s important to know what kind of error must be addressed in a particular case.

There is even official guidance. A flight instructor or student may consult publication FAA-H-8083-9A, the Aviation Instructor’s Handbook,  and find on page 2-28 a discussion of the two kinds of errors: slips and mistakes.

A slip, it says, occurs “when a person plans to do one thing, but then inadvertently does something else.”

A mistake, by contrast, “occurs when a person plans to do the wrong thing and is successful.”

Hard to deny that the student’s action qualifies as a mistake, by that definition.

What about the instructor’s action?

Surely he too did “the wrong thing” and was “successful,” making the action a (big) mistake.

It also might be argued that the CFI’s action was a slip, in that he planned to send a message, “You’re in charge!” but inadvertently conveyed a cloudier concept.

For a more conventional example of a slip, consider when a pilot lands and inadvertently retracts the landing gear instead of the flaps.

For a more conventional example of a mistake, think about when a pilot adds flaps too soon on a landing approach, and must correct the steepened glide path with power.

The anecdote touches on another not-uncommon dynamic of flight training—a trainee’s need to please an instructor (or other authority figure) at all costs, despite one’s own better judgment.

Is that a slip, or a mistake?