Definition
A mechanism on a tailwheel airplane that secures the tailwheel in a straight-ahead position so it cannot swivel freely, providing directional stability during the takeoff roll, landing rollout, and other operations where steering through the rudder pedals is desired without the tailwheel castering.
Plain English
A small mechanism that holds the tailwheel pointed straight so it cannot spin around on its own. With it engaged, the tailwheel acts like a steerable wheel that responds to the rudder pedals instead of swinging freely.
Context Anchor
Seen during preflight checks and before the takeoff roll, especially when confirming the controls can move freely.
Why Pilots Care
Leaving a locking device in place prevents the pilot from moving the controls, resulting in loss of directional control or elevator authority during the takeoff roll and a high risk of runway excursion or crash.
Intuition Check
Do not assume a locking device is always something built into the airplane and safe to leave alone. In this context, it may be a removable item that must be taken out or released before flight.
Example Sentence 1
Before beginning the takeoff roll, the pilot confirmed the tailwheel locking device was engaged so the airplane would track straight down the centerline.
Example Sentence 2
During the takeoff roll briefing, the instructor confirmed the student had verified that no locking device remained attached to the controls.