Unless otherwise stated, obstacle clearance for all departure procedures (SIDs and ODPs) is based on assumptions that the aircraft will:
- Cross the departure end at least 35 feet above departure end elevation;
- Climb to 400 feet above runway departure end elevation before turning;
- Maintain climb gradient > 200 ft/nm until reaching minimum IFR altitude.
Never assume that your aircraft can meet the required climb gradient! Always check the performance data in the pilot's operating handbook (POH) or aircraft flight manual (AFM) to ensure that you can meet these requirements.
Standard Instrument Departures (SIDs) are ATC procedures designed for system enhancement and to reduce pilot/controller workload. They are printed in graphic form, and they provide both obstruction clearance and a transition from the terminal area to the en route structure.
You need to have ATC clearance to use a SID. (AIM 5-2-8)
Obstacle Departure Procedures (ODPs) provide obstruction clearance via the least onerous route from the terminal area to the en route structure. They may be flown without an explicit ATC clearance.
Important points from AIM 5-2-8:
- Do not assume that “cleared as filed” or “cleared direct to” a fix means that you will be clear of terrain and/or obstacles without using the ODP.
- Do not assume that such a clearance prohibits you from using the published ODP. In fact, ATC assumes that you will use a published ODP when departing from a non-towered airport.
