Definition
An Obstacle Departure Procedure is a published, pre-planned departure route designed to provide obstruction clearance from the runway to the en route environment. ODPs are flown using pilot navigation and may be presented as either a textual description or a graphic depiction. They are recommended (not mandatory) for use by all pilots departing under instrument flight rules unless an alternative route is assigned by ATC, and are intended solely to keep the aircraft clear of terrain and obstacles during the climb-out.
Plain English
A published flight path for leaving an airport that keeps you safely above terrain and obstacles like towers, hills, and buildings as you climb out. You fly it yourself by following the route described on the chart.
Context Anchor
You review ODPs during preflight planning for an instrument departure, often in the takeoff minimums and obstacle departure procedures section or on a departure chart.
Derivation
Obstacle means something that stands in the way. Departure means leaving. Procedure means an ordered way of doing something. Together, the phrase points to a planned way of leaving the runway while staying clear of things in the way.
Why Pilots Care
Following the published ODP guarantees the required obstacle clearance when departing in low visibility or at night, preventing controlled flight into terrain.
Grounding Statement
Picture taking off into low cloud near rising terrain: the ODP is the published path that tells you how to climb away without relying on outside visibility.
Intuition Check
Do not assume an ODP is just a preferred route or a traffic-flow instruction. Its main job is obstacle clearance, and it may matter even when ATC does not specifically say it in your clearance.
Example Sentence 1
Before departing the mountain airport in low visibility, the pilot briefed the published ODP to ensure terrain clearance during the climb.
Example Sentence 2
Because the airport had no standard instrument departure, the crew flew the published ODP to reach the initial en route altitude safely.