SIDS & Obstacle Clearance
 

Weather is IMC. Receive a clearance to fly a SID with non-standard climb gradient, no ODP. Does the standard climb gradient of 3.3% keep you clear of obstacles? In other words, can it be assumed that the non-standard climb gradient on the SID serves a purpose other than obstacle clearance since there is no obstacle departure procedure?

5-2-8 of the AIM addresses this. Here is the first paragraph, but more can be found at faa.gov.

5-2-8. Instrument Departure Procedures (DP) - Obstacle Departure Procedures (ODP) and Standard Instrument Departures (SID)

Instrument departure procedures are preplanned instrument flight rule (IFR) procedures which provide obstruction clearance from the terminal area to the appropriate en route structure. There are two types of DPs, Obstacle Departure Procedures (ODPs), printed either textually or graphically, and Standard Instrument Departures (SIDs), always printed graphically. All DPs, either textual or graphic may be designed using either conventional or RNAV criteria. RNAV procedures will have RNAV printed in the title, e.g., SHEAD TWO DEPARTURE (RNAV). ODPs provide obstruction clearance via the least onerous route from the terminal area to the appropriate en route structure. ODPs are recommended for obstruction clearance and may be flown without ATC clearance unless an alternate departure procedure (SID or radar vector) has been specifically assigned by ATC. Graphic ODPs will have (OBSTACLE) printed in the procedure title, e.g., GEYSR THREE DEPARTURE (OBSTACLE), or, CROWN ONE DEPARTURE (RNAV) (OBSTACLE). Standard Instrument Departures are air traffic control (ATC) procedures printed for pilot/controller use in graphic form to provide obstruction clearance and a transition from the terminal area to the appropriate en route structure. SIDs are primarily designed for system enhancement and to reduce pilot/controller workload. ATC clearance must be received prior to flying a SID. All DPs provide the pilot with a way to depart the airport and transition to the en route structure safely. Pilots operating under 14 CFR Part 91 are strongly encouraged to file and fly a DP at night, during marginal Visual Meteorological Conditions (VMC) and Instrument Meteorological Conditions (IMC), when one is available. The following paragraphs will provide an overview of the DP program, why DPs are developed, what criteria are used, where to find them, how they are to be flown, and finally pilot and ATC responsibilities.

Thank you for that. I've already been through it several times, as well as AC 120-91. Still, the question remains unanswered.

DPs are designed using the TERPS criteria for terrain clearance but also take into account ATC needs, and noise abatement. So if there is no ODP and the climb gradient is non-standard I would guess it has to do with juggling arrivals and departures.

Where did you find a DP like this?

There are only two possible answers to this question.... 3.3% or as published.

Birdie:

Yes. If there is a published climb gradient but no ODP published, the climb gradient published is an ATC climb gradient. If you are unable to comply witht the climb gradient, notify ATC. They may be able to waive that restriction or give you another procedure.

If you are using US Government NACO plates, obstacle climb gradients are indicated by a dagger symbology (sword); whereas, ATC climb gradients are published without any special symbology.

If you are using JEPPs, they will say something to the effect of "This SID requires take-off minimums" and will state what is required for each runway. If there is an ATC requirement (which is always higher of course), they will also state "ATC climb of blah blah blah".

In either case, if there is no ODP but there are published SIDs, it doesn't hurt to study terrain charts and/or the minimum safe altitudes published on the approach charts for a sanity check. Publishers (Jepps and NACO) do and often make mistakes.

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Again Birdie, I don't know how else to tell you yes, the answer is YES in reference to your first question.

You always have to meet 3.3% or 200'/NM when departing IFR unless you've been specifically authorized otherwise.

The reason why I suggested it might be a good thing to "know your terrain" is so that chart errors, missing, or out of date pubs don't get you killed. If you are in doubt, ask ATC.

Don't know if you found the answer yet, but here is my $.02.

Answer: I say no. One cannot assume it will provide terrain clearance. Non-standard climb % are given for two reasons, obstacles or ATC crossing restrictions. If you want to know, then ask the facility in charge of the SID.

I would be careful mixing the terms ODP and SID. ODP is for (usually anyway) when ATC "isn't home", while SIDs require one speaking with ATC. ODPs require a certain climb gradient to miss the mountains. SIDs may require a certain climb gradient other than standard for one of the above reasons, which one, well flip a coin?