Plain English Meaning

A gauge that shows how fast the engine is spinning, measured in turns per minute.

Full Definition

A cockpit instrument that displays engine speed, expressed in revolutions per minute (RPM). On a fixed-pitch propeller airplane, it indicates both engine and propeller RPM, since they turn together. On a constant-speed propeller airplane, it indicates engine RPM, which the propeller governor maintains at the value the pilot has selected.

Context Anchor

Seen on the engine instruments, especially when setting propeller speed during takeoff, , , and .