Definition
The specific altitude above the ground at which, when an airplane is flown in a level turn at a given groundspeed, a line extending from the pilot's eye through the wingtip appears to remain fixed on a point on the ground. It is calculated by squaring the groundspeed in knots and dividing by 11.3 (or by 15 if using miles per hour).
Plain English
The height above the ground where, while you circle a point on the ground at a steady speed, your wingtip seems to stay locked onto that point without sliding ahead of it or behind it.
Context Anchor
Used during eights on pylons, where the pilot adjusts altitude as groundspeed changes around each pylon.
Derivation
From 'pivot' — to turn around a fixed point. The altitude is named for the way the airplane appears to pivot around the pylon on the ground when flown at exactly the right height.
Why Pilots Care
Flying at the correct pivotal altitude keeps the turn coordinated so the airplane tracks smoothly around the pylon without slips, skids, or constant bank changes.
Grounding Statement
In this maneuver, the correct height is not fixed; it rises and falls as the airplane’s speed over the ground changes.
Intuition Check
Pivotal altitude is not a single standard altitude for the maneuver. It is a changing height based on groundspeed, not just the number shown on the airspeed indicator.
Example Sentence 1
At a groundspeed of 90 knots, the pivotal altitude works out to roughly 717 feet above the ground.
Example Sentence 2
Below pivotal altitude the pylon appeared to move forward, requiring a climb to restore the correct visual reference.