Definition
A vertical descent path defined by a fixed angle between two waypoints, flown at a constant gradient regardless of groundspeed or wind. In VNAV, the aircraft follows this fixed-angle path to a specified altitude at a specified fix, adjusting vertical speed as needed to maintain the geometry.
Plain English
A descent path that follows a set angle in space — like a ramp drawn between two points in the sky. The aircraft adjusts its rate of descent to stay on that ramp, no matter how fast or slow it's going over the ground.
Context Anchor
Seen in instrument procedure and vertical navigation planning, especially when checking whether a descent will meet required altitudes along the route or approach.
Derivation
From Greek 'geometria' — measurement of the earth or of shapes. Here, 'geometric' means the path is defined by fixed geometry (an angle between two points in space), as opposed to a path defined by time or by a constant rate of descent.
Why Pilots Care
Provides accurate vertical guidance on RNAV approaches, improving safety and precision in descent.
Analogy
Think of it like drawing a straight ramp between two floors. The ramp’s shape tells you the path to follow; your walking speed is separate from the ramp itself.
Intuition Check
Do not read geometric path as just any general route. Here it means a measured vertical path through space, built from distance and altitude.
Example Sentence 1
The FMS commanded a shallower vertical speed as the aircraft slowed, keeping it on the geometric path to the next altitude restriction.
Example Sentence 2
Pilots verify the geometric path angle on the approach chart before starting the descent.