Plain English Meaning

When one engine quits in a twin, you push hard on one rudder pedal to stop the airplane swinging sideways. The foot that isn't pushing tells you which engine has failed — same side as the relaxed foot.

Full Definition

A memory aid used in multi-engine flying to identify which engine has failed. With the airplane held straight using rudder, the foot that is not pressing on a rudder pedal — the 'dead foot' — points to the failed, or 'dead,' engine. The live engine produces yaw toward the dead engine, requiring rudder pressure on the side of the operating engine to keep the airplane straight.

Context Anchor

Used in multi-engine training and in actual engine-failure procedures when identifying which engine has lost power.

Derivation

This is a cockpit memory phrase. “Dead” means inactive or not doing useful work here: the “dead foot” is the foot not actively pressing the rudder pedal, and it points to the “dead engine,” the engine that is no longer producing power.