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-   -   SIDS & Obstacle Clearance (https://www.airlinepilotforums.com/fractional/44028-sids-obstacle-clearance.html)

BIRDIE 09-20-2009 03:48 AM


Originally Posted by KC10 FATboy (Post 681207)
..they will have the proverbial trouble T (a fat looking T symbol) in which the user is expected to reference the takeoff minimums page and read what is required. This is also where you find ODPs.

I think if you took the time to comprehend the original question that started this thread, you would not be talking to me about ODP's. Go back and read it again.

SPDBOILER 09-20-2009 04:01 AM


Originally Posted by BIRDIE (Post 681224)
I think if you took the time to comprehend the original question that started this thread, you would not be talking to me about ODP's. Go back and read it again.

So did you post this question assuming you already know that answer and feel like arguing with people until you get the answer you already think is correct? Good luck on your...well, whatever you are doing.

BIRDIE 09-20-2009 04:09 AM


Originally Posted by SPDBOILER (Post 681225)
So did you post this question assuming you already know that answer and feel like arguing with people until you get the answer you already think is correct? Good luck on your...well, whatever you are doing.

No, I don't know the answer. You think I'm doing this for entertainment? I thought somebody out there may be able to help. What I'm doing is trying to find an answer to an issue that came up in the company. Can you provide an answer or any helpful information, or are you here just to antagonize?

geosynchronous 09-20-2009 05:29 AM

I think one of your earlier posts hit the nail right on the head.

You have to have TERPS or as published. If the FAA determines that 200' the per nm clearance plane is violated, they will publish a procedure for you to fly that will keep you from scratching the paint. The FAR's bind you to flying that "procedure" when it is necessary.

This gets emphasized at FlightSafety every recurrent session.

BIRDIE 09-20-2009 05:55 AM


Originally Posted by geosynchronous (Post 681234)
If the FAA determines that 200' the per nm clearance plane is violated, they will publish a procedure for you to fly that will keep you from scratching the paint.

And that procedue may not necessarily be an ODP. It may be a SID since a SID also provides obstacle clearance.

I have been told that when departing from an airport served by a SID with a non-standard climb gradient AND no ODP, the standard climb gradient (3.3%) will satisfy obstacle clearance in the event of an engine failure. I don't agree with that but I can't prove it.

Anyway, not trying to provoke anyone and I'm not on here for entertainment. I was looking for guidance. Probaby time to drop it and move on. I will plan to meet the non-standard climb gradient OEI until I can prove otherwise.

geosynchronous 09-20-2009 06:04 AM

Here is a problem that we can all work. Maybe this practical example will answer our questions. We seem to be able to quote, cut and paste things pretty well, but let's apply it. Let's keep it fun and contempt free.

Departure from Sioux Falls, SD (KFSD).

It's 0200, the tower is closed. It is dark. The FBO is out of coffee. Starbucks is closed.

Runway 15 is the only runway open. The winds are 150 at 25 anyway. The lineman put a gun to your head, you WILL use runway 15....get the point...?

The ceiling is 100 feet, the visibility is 1/4 mile. You want to fly IFR, it is IFR.

You are Part 91.

There is no published SID. There is the "Trouble "T" in the front fodder of the NACO approach plates.

To quote Keanu Reeves in "Speed..."

"What would you do....WHAT WOULD YOU DO?"

geosynchronous 09-20-2009 06:17 AM


Originally Posted by BIRDIE (Post 681237)
And that procedue may not necessarily be an ODP. It may be a SID since a SID also provides obstacle clearance.

I have been told that when departing from an airport served by a SID with a non-standard climb gradient AND no ODP, the standard climb gradient (3.3%) will satisfy obstacle clearance in the event of an engine failure. I don't agree with that but I can't prove it.

Anyway, not trying to provoke anyone and I'm not on here for entertainment. I was looking for guidance. Probaby time to drop it and move on. I will plan to meet the non-standard climb gradient OEI until I can prove otherwise.

--------------------------------------------------
I do not agree with that either. A SID with a non-standard climb gradient means that 3.3% does not apply. The non-standard part may be 3.4% which is above TERPS. I do not agree with the engine failure element either. The FAA does not care if your engine fails when they are surveying and obstacle clearance plane. Engine failure is a consideration, the new AIM amendment clears this issue. The PC12 pilot has to consider an engine failure just as much as the Citation pilot has to consider an engine failure...the PC12 pilot has to consider more in my opinion.

My KFSD example has no SID published , but it has the Trouble "T"...which is an ODP. If you do the math, it is a 6.6% climb gradient...WAAAY above TERPS.

I am going to do the same thing. I will comply with the ODP or SID, and I will compute performance for OEI and load accordingly. If I am taking off from any airport that does not have a DP or ODP or SID, and if it is 110 degrees and my airplane won't climb at at least 3.3%, then I will flight plan accordingly to maintain that 3.3%, because the FAA has checked that out for me. I am not doing myself (or my passengers) any favors if I can only maintain a 2% climb gradient and I clip a cell phone tower that the FAA determined to be at 2.5%.....below the 3.3% clearance plane.

BoilerUP 09-20-2009 06:33 AM

The un-published ODP for RW15 @ KFSD is climb via heading 150 to 2000', then right turn direct FSD. With 404ft/nm to 1700' climb, STD visibility is 1sm and Adequate Visual Reference is 1/4.

CPCALC shows to make 404ft/nm to 1700' per the ODP, at ISA, our CJ2+ can only depart at 11,569lb at Flaps 15; Flaps 0 is 12,339lb.

APG runway analysis for KFSD RW15 shows, for a Flaps 0 takeoff, we can depart at the 12.5k max structural takeoff weight up to 49C; at Flaps 15 we're max structural to 45C and obstruction limited at 49C to 12132lb.

geosynchronous 09-20-2009 06:42 AM

I'd say the ODP is published. It is in the front fodder of the NACO charts, or it is on the back of the 10-9 Jeppesen chart. There is no "published" DP or SID. If there was a published DP/SID, and if I worked for the FAA, I would call it the "TALL ANTENNA TWO." We don't have this here, just the "Trouble T."

Essentially, I think you are saying that you would load your CJ2 to comply with the 6.6% gradient...and you would consider losing one engine.....I would do the same thing. CPCALC is wonderful.

BoilerUP 09-20-2009 06:59 AM

I meant "unpublished" as in there's not an independent chart for the ODP, such as the SKOTT1 @ Glacier Park or the SARDD1 @ Aspen.

But you're right...it *is* published and easily found.

But back to the APG runway analysis. I understand how to utilize APG data when there is an alternate DP (such as at GPI or ASE), but this doesn't seem quite as clear. APG uses type-specific performance data derived from the same AFM as CPCALC, yet shows a greater allowable weight for departure.

Why is that?


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