Making sense out of ODPs.

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Electric

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Electric
I’m in the middle of my instrument training and just trying to make sense of Obstacle Departure Procedures. Have a specific question:

Departing RW35 in Norwood (KOWD) , ODP states: Turn left heading 315 to 1900 before turning east.

I understand that if my on-course heading requires a turn due east I need to first climb heading 315 to 1900 feet, and only then turn east.

But what about other scenarios:
  1. What if my on-course heading is 350, is it safe to depart straight out? Or should I first climb to 1900 on 315 heading?

  2. What if my on-course heading is 180, can I make an immediate left turn to 180? Or should I turn 315, climb 1900 and then make a RIGHT turn to 180?
Thanks in advance!
 
I normally take a look at a sectional chart to see what obstruction(s) are causing the ODP. In this case, after a cursory look, I couldn't discern the reason for this ODP with a flight path to the east. Good question.
 
I suppose that if you are departing RWY35, turn left and climb if you are heading north or east and before turning east, make sure you are at or above 1900. If you are turning westbound (either to fly west or south) then the ODP doesn't come into play and just turn left when at least 400' AGL.
 
Electric said:
I’m in the middle of my instrument training and just trying to make sense of Obstacle Departure Procedures. Have a specific question:

Departing RW35 in Norwood (KOWD) , ODP states: Turn left heading 315 to 1900 before turning east.

I understand that if my on-course heading requires a turn due east I need to first climb heading 315 to 1900 feet, and only then turn east.

But what about other scenarios:
What if my on-course heading is 350, is it safe to depart straight out? Or should I first climb to 1900 on 315 heading?
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Climb to 1900 on 315 heading, per the ODP. Apparently "straight out" is obstructed. I would consider anything east of 315 to be "east" without further local knowlege.
What if my on-course heading is 180, can I make an immediate left turn to 180? Or should I turn 315, climb 1900 and then make a RIGHT turn to 180?
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I'd consider that to be "not east", and make the left turn.
 
800 and 1450MSL towers directly ahead 35 departure. Also a lot of obstacles on the east side of runway heading. Boston is in the way. I would turn to 315 and climb to 1900 before turning right of 315 heading. Left turn past 315... immediate is fine.
 
Electric said:
OK, I get the idea. Thanks everyone!
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Now if it's VMC and you believe you can stay away from those obstructions, you could turn east. Also ATC might turn you east too so it's up to you to inform them you're doing the ODP. I haven't looked at this airport so I don't know what's out there and/or how close to the runway end. Just know you can turn as long as you're comfortable with it in VMC.
 
mscard88 said:
Now if it's VMC and you believe you can stay away from those obstructions, you could turn east. Also ATC might turn you east too so it's up to you to inform them you're doing the ODP. I haven't looked at this airport so I don't know what's out there and/or how close to the runway end. Just know you can turn as long as you're comfortable with it in VMC.
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But if ATC gives me vectors, they are "required" to keep me safe from terrain/obstacles, correct? Therefore, I should only use ODPs in the absence of specific instruction from ATC. Does that sound right?
 
Electric said:
But if ATC gives me vectors, they are "required" to keep me safe from terrain/obstacles, correct? Therefore, I should only use ODPs in the absence of specific instruction from ATC. Does that sound right?
Click to expand...
Think of it exactly the opposite way. Unless ATC issues you a SID, which also includes obstacle clearance, an ODP is always the pilot's prerogative. This is probably not applicable to KOWD since, given the airspace, I'd be expecting the NORWOOD departure but there are many areas in the US where that would not be the case.

Personal FAQ on ODP Basics:
  • In general, ODPs are optional for plain vanilla Part 91 (but mandatory for Part 121, 125, 129, or 135 operations). 91.175(f)
  • Perhaps its obvious but an exception to the voluntariness of an OPD for plain Part 91 is if ATC assigns the ODP as an instruction or part of a clearance. Then it falls into 91.123.
  • In general, if an ODP is not assigned by ATC, it is the pilot's prerogative to fly it anyway. AIM 5-2-8. In this situation, the pilot should advise ATC of the pilot's intentions; it's always a good idea to be on the same page as ATC.
  • The exception to the pilot's prerogative is if ATC assigns a SID (which includes obstacle clearance) or receives vectors immediately upon takeoff.

Good references are AIM 5-2-8 and the appropriate sections of the FAA's Instrument Procedures Handbook (IPH).

In terms of what ATC does, especially at non-radar airports (towered or not) varies. I've been to airports where I've been assigned an ODP as part of my takeoff clearance and others where I have not. Interestingly, the IPH says ATC will generally not assign an ODP unless also needed for aircraft separation. The ATC Handbook sort of echoes this, it directs controllers to include a textual ODP when "pilot compliance is necessary to insure separation."

Bottom line, obstacle clearance is our job (penalty is out lives, not FAA enforcement) and ATC may or may not take responsibility for us until reaching a proper altitude by issuing vectors or assigning a departure procedure..
 
One caveat about ODPs: You may hear at some point (if you haven't already) that takeoff minimums are not binding on Part 91 flights. However it's important to know that if the climb gradients specified in the takeoff minimums section are not met, then the ODP does not guarantee terrain and obstruction clearance.
 
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