Instrument Oral Question

FrankieFlyCRQ

Well-Known Member
Ok so I came across this question, and I understand the question for the most part, and I understand the answer for the most part, but the problem is I dont understand why this is the answer to the question.

The question is from the ASA Instrument Oral Exam Guide Ch.2 page 2-8 question#9 ...for those who have this book,....

#9. When a DP specifies a climb gradient in excess of 200 feet per nm, what significance should this have to the pilot? (AIM 5-2-7)

Answer stated: If an aircraft may turn in any direction from a runway, and remain clear of obstacles, that runway passes what is called diverse departure criteria and no ODP will be published. However, if an obstacle penetrates what is called the 40:1 slope obstacle identification surface, than the procedure designer chooses whether to:
a. Establish a steeper than normal climb gradient;
b. Establish a steeper than normal climb rate gradient with an alternative that increases takeoff minima to allow the pilot to visually remain clear of the obstacle(s); or
c. Design and publish a specific departure route; or
d. A combination or all of the above.

***OK SOOOO what the heck does any of that have to do with the question, what am I missing here??? **** My understanding of the answer is, if the climb gradient is in excess of 200 fpnm , and the surrounding area from the runway is clear of obstructions in all directions, than the ODP does not apply to the pilot, nor does he have to fly it??? Any explanation of this answer will be awesome, thanks!
 

cre8flyer

New Member
I'd be brave enough to suggest that if the DP requires a climb gradient > 200 ft / n.m. the pilot should review his performance charts to ensure he can maintain the higher climb gradient required by the DP.

I would not rely on there being no obstructions. . . I would fly the DP (or wait for VMC in order to be able to fly something other than the DP).
 

tgrayson

New Member
***OK SOOOO what the heck does any of that have to do with the question, what am I missing here??? ****
I agree that the question they're answering appears to be a bit different from what they asked. Looks like they're giving you the answer to what the procedures designer must do when the runway doesn't meet diverse departure criteria. And they didn't accurately describe what those criteria are. You should learn that more thoroughly from the AIM.

The better answer as to the "significance" is that the pilot may not be able to maintain terrain clearance flying the DP if he cannot maintain the climb gradient. He may not be able to safely depart that runway in IMC.

However, usually when a procedure has a non-standard climb gradient, there will be alternatives if the aircraft cannot achieve the climb gradient, such as higher than standard takeoff minimums, with a required ceiling and vis, or a visual climb over airport (VCOA).
 

FrankieFlyCRQ

Well-Known Member
The better answer as to the "significance" is that the pilot may not be able to maintain terrain clearance flying the DP if he cannot maintain the climb gradient. He may not be able to safely depart that runway in IMC.

However, usually when a procedure has a non-standard climb gradient, there will be alternatives if the aircraft cannot achieve the climb gradient, such as higher than standard takeoff minimums, with a required ceiling and vis, or a visual climb over airport (VCOA).
Yea I figured this is pretty much what they are trying to say, the way you explained it is alot clearer than the book! Thanks again tgrayson!:)
 

FrankieFlyCRQ

Well-Known Member
I'd be brave enough to suggest that if the DP requires a climb gradient > 200 ft / n.m. the pilot should review his performance charts to ensure he can maintain the higher climb gradient required by the DP.

I would not rely on there being no obstructions. . . I would fly the DP (or wait for VMC in order to be able to fly something other than the DP).
Good points made! Thanks man!
 

NewYorkophile

Fly Casual
Just to confirm along similar lines, the standard gradient is 152ft/NM, right? Plus the 35 foot screen height?

What's the lateral tolerance for that, as well?
 

cre8flyer

New Member
The way I learned it was:
1. Minimum altitude of 35 ft. over departure threshold
2. No turns below 400 AGL
3. Standard climb gradient: 200 ft / n.m.
4. Obstacle gradient: 152 ft / n.m.
(the difference between the two gives you 48 ft / n.m. clearance over obstructions)

If higher performance is required the D.P. will include the higher performance required or limit the departure in some way (e.g. by requiring higher visual minimums).
 
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