Definition
A reference point on the base leg of a 180° power-off approach, typically abeam the intended touchdown point on the base leg or at the start of the turn from base to final, where the pilot evaluates altitude, distance, and glide path to judge whether the airplane will reach the runway with the engine at idle. Adjustments to the turn radius, flap setting, or descent path are made at this position to manage energy and arrive on final at the correct altitude and airspeed.
Plain English
A check point on the base leg of a power-off landing where the pilot looks at how high they are and how far from the runway, then decides whether to tighten the turn, extend it, or add flaps to land on the chosen spot.
Context Anchor
Used during the 180° power-off approach, after the power has been reduced and before the pilot turns toward the runway for landing.
Derivation
“Base” refers to the base leg of the airport traffic pattern, the part before the final turn toward the runway. “Key” means an important reference point. Together, “base key position” means the important checkpoint on base used to judge the rest of the power-off approach.
Why Pilots Care
It provides a reliable decision point to confirm the aircraft has sufficient altitude and can be configured correctly to reach the runway in an engine-out situation.
Intuition Check
“Key” does not mean a physical key or a control in the airplane. Here it means an important checkpoint used to decide whether the power-off approach is working.
Example Sentence 1
Passing the base key position a little high, the pilot added a notch of flaps and steepened the descent to stay on profile for the touchdown point.
Example Sentence 2
From the base key position the student initiated a forward slip to lose excess altitude while staying on the proper glide path.