Definition
The rudder pedal on the inside of a turn — that is, the rudder pedal on the same side as the lower wing when the airplane is banked. Applying bottom rudder pushes the nose further into the direction of the turn and is a known contributor to a cross-control stall and incipient spin, particularly during a skidding turn from base to final.
Plain English
When the airplane is banked into a turn, one wing is lower than the other. The rudder pedal on the side of that lower wing is called bottom rudder. Pressing it pushes the nose further around in the direction of the turn.
Context Anchor
Seen in stall and spin awareness discussions, especially when describing skidding turns and low-speed turning errors.
Derivation
Called 'bottom' because in a bank the inside wing is the lower one — physically toward the bottom — and the rudder pedal on that side is therefore the 'bottom' pedal. The opposite pedal, on the high-wing side, is 'top rudder.'
Why Pilots Care
Using bottom rudder during a spin prevents recovery and can turn a recoverable situation into an unrecoverable one.
Intuition Check
Bottom does not mean the rudder is physically on the bottom of the airplane. It means rudder applied toward the lower wing while the airplane is banked.
Example Sentence 1
When the student overshot final, the instructor warned against adding bottom rudder to tighten the turn and instead had her go around.
Example Sentence 2
During spin practice the student mistakenly applied bottom rudder, requiring the instructor to take the controls and apply opposite rudder to stop the spin.