Course reversal on a GPS approach
 

If I'm doing a course reversal on a GPS approach with a hold style procedure turn and the hold is depicted as 4nm, do I also need go 4 nm out on the procedure turn?
I believe I do, but would like some confirmation.

I would say no, but I don't have anything regulatory to back that up.

I see no reason why you could not go less than 4nm provided you can become established before the holding/IF/IAF fix, but I would not go more than 4nm, unless you are assured the MSA extends beyond 4nm and you are at or above it.

Experts, the cyberspace is yours..........................

Actually I agree with you now. i was overthinking it. You wouldn't go out 4 nm on a hold entry you'd just go the one minute or so. As long as you stay in the protected area the entry/course reversal wouldn't need to be 4 nm.

Amendment
 

I added a caveat about MSA. Do you have a particular approach in mind, or just in general?

winds, a/c category/performance, etc could also be a factor

Another caveat - restricted airspace beyond 4nm. I gotta quit thinking.

good question!

It's kind of an interesting question and I've heard a lot of folks express different opinions about it with language fro the AIM they claim supports it.

I come down on the side of, 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 (including GPS holds), then you use distance to determine all of the outbounds, including the first. That's answer is not crystal clear from the FAA material but I get there when I think about holds that are =not= 4 nm.

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 rather than 4. The fact that it's not a standard length tells me that there's gotta be a reason for specifying a leg lenght. 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.

That suggests to me that ATC is anticipating that, if you have crossed DOCKY outbound, you're not going to turn inbound for 7 miles. And that you shouldn't (without permission anyway - 7 miles is a long time in a trainer and I generally ask ATC for shorter).

Not for the procedure entry according to the AIM. But as we all know, the AIM lists 3 'recommended' holding entry procedures and none of them are regulatory in nature.

If I were flying the entry, I would do the standard 1 minute outbound (winds depending) before doing the turn back inbounds. Be sure to stay in the protected area.

Once established in the hold, fly the 4NM holding pattern.

According to TERPS criteria, the holding pattern size for an RNAV or GPS is based upon the minimum holding altitude (7130.3A). This of course could change if military aircraft were flying (requiring a higher airspeed) which requires a larger template evaluation area, which typically results in an expanded pattern size due to picking up higher obstacles.

Really? Where does the AIM say to use timing for the entry to a distance hold?

There is a note immediately following the description of timed holds that says
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NOTE-
The initial outbound leg should be flown for 1 minute or 1 1/2 minutes (appropriate to altitude). Timing for subsequent outbound legs should be adjusted, as necessary, to achieve proper inbound leg time. Pilots may use any navigational means available; i.e., DME, RNAV, etc., to insure the appropriate inbound leg times.
==============================

But the very next paragraph says
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5. 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.
==============================

Not the clearest in the world, but the Note appears to be associated with the timed hold paragraph and the distance paragraph says to use distance instead of time for the entry as well as the rest of the hold.

That paragraph does not really indicate whether you use distances in lieu of the procedure entry. It is talking about the legs of the pattern.

If you were to use DME for an ATD hold using GPS, this begs the question about flying a certain DME on a holding entry when you are not established on a leg of the holding pattern but you are located somewhere in the protected area.

For example.. you enter a GPS 4NM holding pattern using a teardrop entry. How far will you know to fly before turning by using onboard GPS equipment? The distances of the pattern are based on the legs- not the area inside the protected zone.

The only way you would know when to turn is if your GPS is constantly giving you a distance away from the holding fix even after it switches to the hold mode.

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If you read page 5-3-12 "Entry Procedures" it clearly states for parallel and teardrop entries to use time.

Parallel Procedure "...outbound on the nonholding side for one minute"

Teardrop Procedure "turn outbound to a heading for a 30 degree teardrop entry within the pattern (on the holding side) for a period of one minute..."

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Ultimately, the AIM is non-regulatory and you can enter the holding pattern however you want. Just be sure to stay inside the protected area :)!

AIM 5-4-9 Procedure Turn and Hold in-lieu of Procedure Turn
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5. A holding pattern in lieu of procedure turn may be specified for course reversal in some procedures. In such cases, the holding pattern is established over an intermediate fix or a final approach fix. The holding pattern distance or time specified in the profile view must be observed. For a hold-in-lieu-of-PT, the holding pattern direction must be flown as depicted and the specified leg length/timing must not be exceeded. Maximum holding airspeed limitations as set forth for all holding patterns apply. The holding pattern maneuver is completed when the aircraft is established on the inbound course after executing the appropriate entry. If cleared for the approach prior to returning to the holding fix, and the aircraft is at the prescribed altitude, additional circuits of the holding pattern are not necessary nor expected by ATC. If pilots elect to make additional circuits to lose excessive altitude or to become better established on course, it is their responsibility to so advise ATC upon receipt of their approach clearance.

From what I can gather reading this paragraph (specifically the bolded and underlined sentences) it would seem that the FAA and NACO want pilots to fly the hold exactly as published with an additional emphasis on not exceeding the leg length limitations shown on the chart. This implies to me that they would like you to fly the hold legs (both entry and subsequent legs - as discussed in earlier postings) to the exact specs listed on the chart therefore, proceeding all the way out to 4 NM (for example) on a normal entry for a depicted hold on a normal GPS Approach.

Additionally...

FAA Instrument Procedure Handbook - Chapter 5, Page 5-39
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". When a holding pattern is published in place of a procedure turn, pilots must make the standard entry and follow the depicted pattern to establish the aircraft on the inbound course"

The above passage is referring to the "Holding" Section in Chapt 5 of the AIM where it states (as noted in previous postings) that if a distance is noted instead of a time, then the entry and subsequent legs will be determined by distance instead of time as well.

Since the depicted pattern in question has a distance instead of a time shown, then I believe that this passage (and the reference to "standard hold entries" in the AIM) also favors using the whole depicted 4NM (for example) on a normal GPS hold.

Finally, as others have said, I do NOT believe that this is a 100% definitive explanation however, in my opinion, it would seem that the FAA and NACO are trying to tell us (in their noisy, convoluted Lawyer language) that we should do what it says on the plate and since it says 4NM on the plate, I will fly out to just a little prior to 4NM and then make my turn back inbound when doing this course reversal. I believe the one thing all of us can agree on is that a pilot will be safe AS LONG AS he/she remains WITHIN the 4NM on the outbound leg of the hold entry. If you turn early or right at 4NM, either way, you will be safe as long as you do not go beyond the 4NM limit.

What if you are doing a teardrop entry? You aren't on an 'established' 4NM GPS Leg.

That's my point.

Yes it makes sense for any entry using a DME leg with a specified distance to use that distance; however, what if you aren't on a leg at all?

==============================
5. 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.
==============================

I usually tell students just use the one minute then once established use the 4nm for the legs ... lets say you used a teardrop entry and flew out for 4nm, you would have to make one really shallow turn to come back in to intercept that inbound course ... if you stick with the 1 minute entries its just fly out for 1 minute then should be right about a standard rate to intercept your inbound course which establishes you in the hold ... just my .02 and what i tell my guys to do i think its easiest ... no references sorry

This was the topic of discussion just yesterday in my office. I had also taught what you state above OHPilot213, but after further review yesterday into the Instrument Flying Handbook and the AIM, and keying in on the points made by FBK and NGDI above, I think that I was mistaken in teaching such. I htink that way was appropriate when GPS was not available, but I think that now if a DME / leg length is dictated then the ENTRY into the holding pattern should be flown referencing the NMs.

USMCFLYR

Ok, the only problem I had with that is if I do lets say a teardrop entry like i said earlier, if i fly outbound for 4NM it will probably take me a lot longer than 1min in most single engine trainers. When you go to make a turn back to intercept the inbound course you really would not know how steep/shallow to make the turn so it can be relatively continuous, If you use the 1 minute outbound for the entry then it should be a consistent and continuous bank standard rate turn back to intercept the inbound course. Also when the 4NM is depicted on a GPS approach plate it usually has a line on the outbound leg at the end of the leg, my interpretation is that this is the point in the hold where you should be 4NM from the fix you are holding around, not at any other point during the hold including the entry. Not sure what others think, I just need a little more convincing evidence and reference before I teach it a different way, plus my method works and I know many others that teach it my way too.

As others have said though - the leg has now been defined for *some* reason. Yes - when it was a timing problem, the 1 minute outbund during the entry would set you up close the required holding time for the inbound leg, then you adjusted accordingly for the proper timing.
For *some* reason now - they want you to fly a 4 mile leg. So you fly out to the 4 miles, turn inbound with an intercept heading and you find yourself on an approx 4 nm leg inbound. I don't remember a constant rate turn on a teardrop putting you right back on the inbound course in case. I thought you took a 30 deg cut back to the inbound course and intercepted it. I remember a no-wind, perfectly flown (constant airspeed and AOB) 90/270 doing that :)
Yep - I taught it your way to in the past. Personally - I think I was wrong now. Not that I will be teaching anybody - anything for a long time, but I would use the aforementioned references and change my approach if I found myself in such a position. I understand your position though and I'm just on the other side of it. I know need more convincing that it is the *other* way.
If I get a chance through, maybe I'll do a little more indepth research and see if I can come up with some more information one way or the other.

USMCFLYR

I just developed a holding pattern and placed a fix exactly 4NM and (30 degrees off the inbound course) in the location of where a teardrop entry would take place using the smallest template that TERPS currently uses. In this instance, the 4NM spot (located in the protected side of the pattern) does not exceed the limits of the holding template.

If your equipment allows, it would be perfectly safe to get a dme/gps readout directly from the entry fix.

Likewise, timing also would suffice considering we use very similar (sometimes the same) template sizes based on airspeed as well.

Both methods would keep you in the protected area which is the whole intent of a holding pattern.

If you continue reading that same passage on 5-3-13 of the AIM, it says "Some GPS overlay and early stand alone procedures may have timing specified." So timing MIGHT be used on a GPS hold rather than distance. It just depends.

When I used to teach, I used to teach simply using 1 min for the entry as well o0n a 4NM GPS Hold but, like USMC, I believe the texts show more support for the 4NM entry leg, regardless of entry type (TD or P).

It seems kind of over-kill in my mind to fly OB for 4NM on a teardrop entry but the only thing that is 100% definitive in the AIM about this topic is as long as you remain within the 4NM barrier, you will be protected. I suppose the FAA and NACO design the hold procedures to account for this 4NM TD entry type.

Maybe the AIM's procedure not to exceed 200 KIAS during a procedure turn (and a hold in lieu of a PT I would assume as well) helps to keep you from straying to far away from the Inbound Course when doing a teardrop entry.

Clear as mud lol

True enough. If the chart or the clearance doesn't mention distance, you use time, GPS or no GPS. That was especially true in the early overlays and GPS approaches that were essentially overlays put on their own piece of paper. They were already timed holds. No need to change them at that stage. Probably aren't too many of those left anymore.

The issue that got me interested in the question is not so much the distance v. time argument about entries but varying published distances. There are, for example, two GPS approaches in the Denver area that have 7 NM holds associated with them rather than the more common 4 NM. One is the co-located HILPT and missed hold for the KAPA GPS 28; the other is the missed hold for the KBJC GPS 29R.

That's what got me to thinking. Why 7 instead of 4? I'm not satisfied with my own guess that it allows for ATC to let other aircraft "cut across" the hold without losing IFR separation based on where the holding aircraft is expected to be. Sounds too dicey. But it still leave the question for me of why the differing sizes.

As someone who works in this area, do you have some guidance for an answer?

The 7 was used instead of 4 because of the altitude that you are holding at those fixes. When you hold at a higher altitude (per FAA criteria) there tends to be more terrain issues and the aircraft tend to be faster with larger turn radii. As a result we use a larger template size which causes us to evaluate a larger area. The larger area is directly associated with the DME or GPS distance associated with the hold.

When we design the holding pattern on an approach, all we do is look up what altitude we want to develop the pattern at (which is determined by obstacles, terrain, or air traffic request). Then we look up what template size based on the speed and altitude of aircraft. Then we choose the corresponding leg length.

These leg lengths were developed in criteria meetings in Flight Standards which determine what is considered "safe" design.

For example (Per regulation 7130.3a): A hold at 4000 and 200KTS tells us to use a pattern 5 on a GPS approach. Pattern 5 templates require a 4NM leg length.

I hope that clears it up.

Hmm. Distance based on msl rather than AGL? Interesting. Speed limits are based on AGL But I do see that according to the AIM, max holding speeds are based on msl.