Distance Holds

MidlifeFlyer

MidlifeFlyer

Well-Known Member
There have been a number of discussions about whether you use distance or time for the initial entry outbound in a holding pattern defined by distance. From those discussions, it appears there are decent arguments on both sides.

My personal view is that if the hold is one that is time based, then the general 1-minute out and then start timing inbound to get as close to 1-minute inbounds as you can is the way to go. But, if the hold is distance-based, then you use distance to determine all legs, including the initial entry outbound.

But I'm not trying to rehash the argument. Instead I want to a theory with the ATC folks here.

Here's the RNAV 28 into KAPA.
http://aeronav.faa.gov/d-tpp/1101/05715R28.PDF

It has a co-located HILPT and MAPT at DOCKY with 7 nm legs instead of the more typical 4. The fact that it's not a standard length tells me that there's gotta be a reason.

My guess is that the reason in this case is traffic separation component, since DOCKY is pretty much right on the approach path to DIA - there are 4 N-S runways with approach paths that cross not too far above in the same vicinity.

Those 7 NM legs suggest to me that ATC is anticipating that, if you have crossed DOCKY outbound, you're not going to turn inbound for 7 miles.

If the reason for the leg length is traffic separation then it shouldn't make any difference whether it's 4 or 7 or 2.

ATC folks - are some of these holding pattern located or sized in a way that you use them for traffic separation as I'm guessing?
 
I'm definitely not a terpster, but I don't see how it'd be separation from traffic. If you've got a plane holding at 9,000 and another inbound at DILVY - DOCKY at 8,100 as published, thats a problem. I'd have to guess its terrain or possibly just the convenience of the hold coming inbound over DILVY to have a reference point.
 
Read the AIM 5-3-7 it specifically discusses DME holds

"Distance Measuring Equipment (DME)/ GPS Along-Track Distance (ATD). DME/GPS holding is subject to the same entry and holding procedures except that distances (nautical miles) are used in lieu of time values....."
 
Bandit_Driver said:
Read the AIM 5-3-7 it specifically discusses DME holds

"Distance Measuring Equipment (DME)/ GPS Along-Track Distance (ATD). DME/GPS holding is subject to the same entry and holding procedures except that distances (nautical miles) are used in lieu of time values....."
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Happen to agree with you and that it means that the entry is subject to the distance requirement.

But that's not my question, just context.

My question is simply whether the length of published holds sometimes have a traffic separation purpose.
 
MidlifeFlyer said:
Happen to agree with you and that it means that the entry is subject to the distance requirement.

But that's not my question, just context.

My question is simply whether the length of published holds sometimes have a traffic separation purpose.
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Possibly. The majority of the distance holds I've seen have been part of GPS IAPs (mostly as part of the missed, but also as course reversals for when you're doing the full procedure), but it is my understanding that ATC can assign a distance hold whenever they want as long as you're equipped for it. When ATC assigns it, I would think it has something to do with traffic (easier for them to moniter the hold on radar etc etc).
 
I can't give you a definitive answer. But at my facility the only thing we care about it whether you remain on the correct holding side. Entry and length of the legs are largely unimportant to me. If your hold has a possibility of encroaching on another facility's airspace, I've already made the point out anyway, and I'm not going to run traffic by you at the same altitude on the holding side of your final/fix/navaid.
 
I'd venture a guess that it has more to do with holding aircraft in the same piece of sky, regardless of holding airspeed. For example, we hold at 230 kts generally, and using the 1 min (or more likely 1.5 min at altitude) means we cover a lot more ground than a Cessna executing the same timing stacked down below us. If we have posted 10 NM legs, then both of our aicraft are assured to remain in the same protected piece of sky regardless of IAS differences.
 
MidlifeFlyer said:
Happen to agree with you and that it means that the entry is subject to the distance requirement.

But that's not my question, just context.

My question is simply whether the length of published holds sometimes have a traffic separation purpose.
Click to expand...

Must have misread one of the early posts. I thought someone was asked if you still do timing for the first leg outbound on a DME hold... I can see giving a DME hold to keep planes withing a specifc airspace. That would keep a plane flying faster out of trouble if the 1.5 minute time would take them too far out.

Another interesting topic on holds you hear discussed is the Parallel entry and how it puts you on the "unprotected" side initially. I have flown with people in the past that absolutely refuse to do parallel entries.
 
Bandit_Driver said:
Another interesting topic on holds you hear discussed is the Parallel entry and how it puts you on the "unprotected" side initially. I have flown with people in the past that absolutely refuse to do parallel entries.
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In jets, we were required to take a correction back to the hold radial after the initial entry put us on the non-maneuvering side. I believe it was if you were over 180 KTAS, but I still do it regardless while doing a parallel entry, even now in helos. I've got no problem doing one.
 
i've never had a problem with them either and i too make the initial turn back inbound to the "protected" side. I just don't know why some get so worked up about it. ATC isn't going to be driving traffic that close to the hold.
 
The G1000 seems to do exactly what the AIM does. If you do a published hold that has DME legs, it will fly the entry to what ever that DME is. The AIM seems pretty clear to me and I don't really see why there is an argument.
 
I have no idea why the legs are the depicted length, but I am fairly certain if a controller is using the difference between 7mi/4mi legs as a basis for separation they are an idiot. I use altitude when separating from holding airspace always unless a significant distance away. I have seen it multiple times where 4 aircraft simultaneously stacked up on the same published hold fly 4 significantly different tracks.
 
Bandit_Driver said:
Another interesting topic on holds you hear discussed is the Parallel entry and how it puts you on the "unprotected" side initially. I have flown with people in the past that absolutely refuse to do parallel entries.
Click to expand...

In truth, there is just more protected airspace on the "protected" side vs. the "non-protected" side, but in practice the whole protected/non-protected terms are only relevant in a non-radar environment, where we have to have some idea of how far away from the holding fix we can discontinue vertical separation. If radar is being used, we just use 5nm and/or 1000' from each aircraft in the stack.
 
MidlifeFlyer said:
My personal view is that if the hold is one that is time based, then the general 1-minute out and then start timing inbound to get as close to 1-minute inbounds as you can is the way to go. But, if the hold is distance-based, then you use distance to determine all legs, including the initial entry outbound.


It has a co-located HILPT and MAPT at DOCKY with 7 nm legs instead of the more typical 4. The fact that it's not a standard length tells me that there's gotta be a reason.
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But a "HILPT" isn't the same as a "hold". A "hold" is a waiting maneuver which is assigned airspace according to terps for holding patterns, but a "HILPT" is a procedure turn for an IAP which does not meet terps airspace requirements for a typical turn anyway you want on the barbed side within 10nm, so the PT is shaped like a holding pattern with DME or other distance/space limits.
 
I know what the AIM says, that said I typically use timing if I'm flying something that's slow enough where I won't exceed the length of the holding leg during the maneuver? Why? It gets me established in the hold quicker. That's just me though.
 
Bringing this one back for a moment. Turns out that the FAA Chief Counsel's office did a interpretation in January that answered about 5 questions. One dealt with distance holds.

http://www.faa.gov/about/office_org...0/interpretations/data/interps/2011/Young.pdf

It's the last one, at the top of page 3. You can shorten the legs of a published distance holds, so long as (a) you remain inside the leg length and (b) ATC didn't specify the leg length in the holding clearance.
 
MidlifeFlyer said:
It's the last one, at the top of page 3. You can shorten the legs of a published distance holds, so long as (a) you remain inside the leg length and (b) ATC didn't specify the leg length in the holding clearance.
Click to expand...

This one makes some good sense.
 
I always have done distance for entrees. Only change is on teardrops. I do the entry for one minute to get the proper hold width and then turn to the outbound heading till I hit the DME.
 
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