Definition
A flight path leg, typically programmed in a Flight Management System (FMS) or area navigation (RNAV) procedure, that directs the aircraft to fly a specified course (ground track) until it reaches a defined altitude, at which point the leg ends and the next leg begins.
Plain English
A segment of a flight path where the aircraft follows a set direction until it climbs or descends to a particular altitude. The altitude is what tells the system the leg is finished, not a waypoint or distance.
Context Anchor
Seen in instrument procedures and GPS or flight-management-system route coding, especially during departures, arrivals, and missed approaches.
Derivation
The name describes the leg's two defining elements: a course (the direction to fly) and an altitude (the condition that ends the leg). It is one of several standardized ARINC 424 leg types used to code instrument procedures.
Why Pilots Care
Ensures obstacle clearance and correct sequencing in published procedures.
Grounding Statement
Picture climbing after takeoff on a published direction; you keep flying that direction until the altimeter reaches the required altitude.
Intuition Check
Do not assume this segment ends at a waypoint or after a set distance. It ends when the aircraft reaches the specified altitude.
Example Sentence 1
After takeoff, the departure procedure begins with a course-to-an-altitude leg, holding runway heading until passing 1,500 feet.
Example Sentence 2
The RNAV departure specifies a course to an altitude of 2500 feet to clear terrain.