Holding Pattern Obstacle Clearence...anyone know?

[SierraPilot123]

Does anyone know what the obstacle clearence/ protection area is for holding patterns?

I.e. 4nm of the fix you get 1,000 ft. and 2nm secondary area 500 ft? I have also heard you might get more like 10 nm on the holding side and only 4 on the non holding side.

I can't find anything in the AIM, TERPS or on the internet about this.

Thanks

[img]http://www.pilotsweb.com/train/art/hold01.gif[img/]

[surreal1221]

Fixed.

[tgrayson]

Originally Posted by SierraPilot123

Does anyone know what the obstacle clearence/ protection area is for holding patterns?

There are many sizes of holding patterns, but the one below is the smallest one that will be TERPed.

[SierraPilot123]

Just what I was looking for guys. Thank you very much.

[fish314]

Here's the Bible on how holding patterns are built in the US. It's FAA Order 7130.3A:

http://www.faa.gov/about/office_org/...ia/7130-3A.pdf

There is some more information from FAA Order 8260.3 here (the TERPS reg):
http://www.faa.gov/about/office_org/...260.3_1-18.pdf



Long story short is that there are 31 different templates that can be chosen from for aircraft, plus a few others for copter holding. You won't really know which one was used for your given holding, at your given altitude, so in flight there really isn't a convenient way to figure out how big the protected airspace is.


As for the obstacle clearance, in the primary area, it's 1000 ft, and at the inner edge of the secondary area it's 500 ft and tapers down to 0 ft at the outer edge of the secondary area. If you are supposed to climb in the holding pattern then starting from the point that you enter the pattern from the previous segment (missed approach, initial takeoff, or whatever else the TERPster used) they go out 40:1 from that point to the edge of the primary area, and then they continue out 12:1 to the edge of the secondary area.

But the key to this whole thing, is that it's nearly impossible while flying the airplane to know which pattern the TERPster used. So it's impossible in flight to tell how much protected airspace you have, and impossible to tell for sure how much obstacle clearance you have. But if you are in level flight, and basically in the holding pattern, you should have at least 1000' (and in most situations a lot more than that), and if you are climbing in holding, you should have the same clearance that you would have if you were doing a diverse departure (at least 48'/NM).

[fish314]

Dammit Tgrayson,

You beat me to it, AND with a pretty picture. I'm so jealous. Awesome post!!

Hey, where did you find the reference that says template #4 is the smallest that would be used for HILOs, Missed approaches, etc.? What would they use templates #1, 2 and 3 for? (They're a little smaller than #4, which is why I'm asking.)

[tgrayson]

Originally Posted by fish314

Hey, where did you find the reference that says template #4 is the smallest that would be used for HILOs, Missed approaches, etc.? What would they use templates #1, 2 and 3 for? (They're a little smaller than #4, which is why I'm asking.)

TERPS, paragraph 292(c).

The holding patterns in 7130.3 are also used for holding that isn't TERPS related, such as for ATC purposes, so I assume that's what 1-3 are used for. It looks like 1 & 2 are specifically restricted to 175 knots.


(BTW, already had the picture uploaded from previous raising of this question.)

[fish314]

Thanks!