I believe that 91.175 governs this, could be wrong on the reg. You will fly the ODP unless you have an alternate procedure (a SID, vectors, etc). Its no longer optional for 121 or 135 on an IFR flight plan. And as another person posted, make sure to rectify a clearance that takes you out of compliance with an ODP if you aren't on a SID. I've been told to fly straight into a mountain after takeoff, instead of doing the ODP.

I have a question also....

You're at a non-towered airport, weather is low,and you can't meet the climb gradient of the ODP. (but do meet standard IFR climb gradients 3.3%) You also do not have the weather in the "OTHER" section and changing runways is not an option. Are you still legal to t/o seeing how ODP's are optional? This is for a part 135/121 trip.

If you're not compliant with an ODP's climb gradient I would think it's illegal to use the procedure. But in leiu of the procedure is there any other way to depart legally? I would think not because then you have no real obstacle clearance guidance in the case of single engine. This is also assuming your not in contact with center yet to receive a vector. And even if you did receive a vector, if you lost an engine you may hit the mountain side well before reaching the 400' before making your turn.

We have a few airports that have gradually rising terrain for a few miles before the sudden mountain shoots up. Our planes, single engine, would barely be able to climb over the gradual terrain let alone the mountain. And we certainly would hit the mountain before reaching a safe turning altitude to avoid the shallower terrain..


In my mind I wouldn't do it, but is it legal?

I was under the impression an ODP is issued when the standard climb gradient/procedure doesn't meet the required terrain clearance, hence the turn and higher required climb gradient to meet the required terrain clearance.

So i'd say no. You would have to reduce the planes weight to meet the climb requirements.

That said both 121 companies I worked for had runway analysis (which would limit a/c weight to ensure the appropriate climb gradients/terrain clearance were met for each specific runway) and if terrain clearance was an issue a "special engine out procedure (which was runway specific) used to meet required terrain clearance.

These are my understanding as well but I could be wrong. I have no idea where I'm getting it from but I remember hearing multiple times from multiple people that under 121 you are required to do the ODP unless cleared otherwise. I always ask for a VFR climb on course if the weather is good and center will ask if I can maintain terrain/obstruction clearance through xxx altitude. I say I can and they give me the VFR climb on course.

ODP's are generally issued when TERPS criteria cannot be met. Like most mountaneous airports. But even then there are still some instances where a minimum climb gradient exhists for an ODP. That's the exact reason I was asking. We can meet standard IFR cl. req. But cannot meet the ODP %. I agree that the only way to meet it would be to reduce weight.

We had runway analysis at one of my former airlines also. Made it much easier. Unfortunately, in my current gig we on our own. If we told a dispatcher we couldn't go because of a ODP climb gradient we'd get the "deer in the headlights" look. They simply don't know this stuff.

So I think the answer is it would be illegal to depart on a pt. 135 trip not being able to meet the ODP gradient % (even if you could meet standard IFR 3.3%)....Especially since we can't just depart into low ceilings and vis, and make a turn seeing how we still have some rising terrain preceeding the mountain obstacle.

That is correct. It comes from OpSpec C077.

If I remember correctly, an ODP is optional, either in VFR or IFR conditions, and was created for the second condition when climb gradient could not be achieved.

A SID on the other hand, requires an ATC clearance, in either VFR or IFR conditions.

I could be mistaken though....

An ODP in not optional for 121 or 135. You must follow the ODP when not given specific intructions in your clearance (SID or heading).

I was referring to Part 91 though, and should have made that clear in my earlier post.

I like to think of it as this. Do what tower tells you, whether it be a SID or a vector. If they don't tell you how to transition (the tower is closed) fly the obstacle departure. If none exists for that RWY turn at 400'.

I do it whether it's IFR or VFR for practice.