GPS Approach question

[ackattacker]

I hate to post what sounds like a newbie question... but an informal survey at work reveals a large variety of opinions on this one from a group of supposedly professional pilots.

The question involves a GPS standalone approach in the typical "T" configuration.

graphically it looks kinda like this:

A (IAF)
|
| 3000/noPT
|
/---- B (IF/IAF)----------FAF--------MAP
\---- |
| 3000/noPT
|
C (IAF)

If it's not clear, there's a holding pattern course reversal charted at "B". I wasn't able to make it look right, the holding pattern should be off to the left (west).

No where else on the approach (other than the two feeder routes) is "NoPT" written.

So clearly, if you go to "A" or "C" then you go in with no procedure turn.
If you go to "B" from the east then you'd need to use the procedure turn.
But what if you go directly to "B" from the west? My initial response was that since there's no "NoPT" arrival sector charted, then you need to do the procedure turn.

But it seems like a lot of people go directly to B then straight to the FAF without doing the procedure turn. And looking it up in the AIM, it's clear that the intent of this sort of "TAA" approach is just that - no procedure turns. But the AIM sample charts all have NoPT approach sectors charted. I can't find it written anywhere that you would be authorized to skip the PT without having is specifically spelled out on the approach.

To make matters more confusing, when loading this approach on the Garmin GNS400 from direct B, the box asks "Hold at B?" Implying that it's legal either way.

Hopefully someone can clarify with a reference...

 

[Geronimo4497]

I don't have a reference for you, but it is SOP for our company to do a procedure turn in the case that you described. I'm sure there are plenty of folks out there with different opionions (insert famous quote here), but for me, if the plan view does not say NoPT, round and round we go. The PAX should not care (I hope) and in reallity, it probably only adds another 2 minutes to the flight.

 

[blimpguy]

NoPT

If Terminal Arrival Areas are depicted, the straight-in sector for western arrivals should look like a semicircle defined by a line connecting the A and C IAFs and within 30NM of B. This should indicate NoPT on the TAA depiction, but won't show it on the holding pattern itself. If no TAAs are depicted and there is only a holding pattern procedure shown for arrivals from the west, there is a terrain or airspace requirement for the procedure turn and it is required.

 

[midlifeflyer]

It would help if you would look at a specific chart. The "Standard T" configuration usually creates a semicircular area (with the T as the base) that is all NoPT.


From the Pilot/Controller Glossary

==============================
AREA NAVIGATION (RNAV) APPROACH CONFIGURATION:
a. STANDARD T - An RNAV approach whose design allows direct flight to any one of three initial approach fixes (IAF) and eliminates the need for procedure turns. The standard design is to align the procedure on the extended centerline with the missed approach point (MAP) at the runway threshold, the final approach fix (FAF), and the initial approach/intermediate fix (IAF/IF). The other two IAFs will be established perpendicular to the IF.
==============================

 

[ackattacker]

One of the charts I specifically have a problem with is the RNAV (GPS) RWY 24L into GUM. Most of you probably don't carry around pacific approach plates, but if you're in AOPA you can pull it up on their website.

If you can pull it up take a good look at it. I can assure you that at 3000' (the altitude at the IAF/IF) there are no obstacles of any significance for 100 miles in any direction. There's even a feeder route nearly straight into the IAF/IF that doesn't specify NoPT, but I can assure you that Guam Center would be less than happy if you started spinning around out there without telling them.

As Midlifeflyer pointed out, the whole point of a T approach is to eliminate the need for procedure turns. You should be able to go straight in from that whole 180 degree area. But if it's not spelled out on the plate... I guess you have to do it? It seems idiotic.

ALL of the GPS approaches in this region look like this. Look at the RNAV (GPS) RWY 6R into GUM. Or the GPS 9 or GPS 27 into ROP. In fact there's not a TAA arrival sector charted in the entire Pacific Chart Supplement.

Even better... look at the RNAV (GPS) RWY 4 into TKK. It has a IF/IAF (FIGBI), which does NOT have a course reversal charted OR a NoPT arrival sector... it has a holding pattern depicted but it's part of the missed approach, not the initial. So if you went direct FIGBI (which you could do, since it's an IAF), what do you do when you get there?

 

[Geronimo4497]

If you can pull it up take a good look at it. I can assure you that at 3000' (the altitude at the IAF/IF) there are no obstacles of any significance for 100 miles in any direction. There's even a feeder route nearly straight into the IAF/IF that doesn't specify NoPT, but I can assure you that Guam Center would be less than happy if you started spinning around out there without telling them.

I guess I should have clarified my statemnet a little better. If in a Non Radar environment, I would perform a procedure turn.


How's life in the land of the snakes? I sort of regret not say yes to the ATR ground school back in 2004. Are you in the 402? I was watching one on flight tracker a while back crossing the pacific towards Hawaii. That must be a huge ferry tank that goes into the fuselage.

 

[CFIse]

One of the charts I specifically have a problem with is the RNAV (GPS) RWY 24L into GUM. Most of you probably don't carry around pacific approach plates, but if you're in AOPA you can pull it up on their website.

If you can pull it up take a good look at it. I can assure you that at 3000' (the altitude at the IAF/IF) there are no obstacles of any significance for 100 miles in any direction. There's even a feeder route nearly straight into the IAF/IF that doesn't specify NoPT, but I can assure you that Guam Center would be less than happy if you started spinning around out there without telling them.

This is one of those situations where it may be safe not to do the PT, but it's not legal. And - as you note, the controller probably doesn't expect you to do the PT either.

The only advice is clarify what the controller wants and what you're willing to do before you get to CIBOL - but this is one of the major problems with the current crop of published approaches. I was on frequency when a CFI-I candidate on his checkride was cleared to the center of the T, not an IAF in this case, and cleared for the approach. He negotiated a legal clearance out of the controller eventually - but to this day the controller has no idea why what he originally offered wasn't acceptable - and more to the point IS being accepted almost daily.

 

[ackattacker]

I guess I should have clarified my statemnet a little better. If in a Non Radar environment, I would perform a procedure turn.


How's life in the land of the snakes? I sort of regret not say yes to the ATR ground school back in 2004. Are you in the 402? I was watching one on flight tracker a while back crossing the pacific towards Hawaii. That must be a huge ferry tank that goes into the fuselage.

Actually, GUM is a radar environment. A TRSA, believe it or not. Sadly, we no longer have 402's out here. They went back to earn their bread and butter doing the "ack attack" . I saw the ferry tanks they used and they're not as impressive as you might think. I'd be a little nervous...

Also, the only snakes I've ever seen out here were dead ones. Either they hide well or their numbers are overrated. We do squish impressive numbers of frogs every night. They just sit there on the taxiways and don't get out of the way.

 

[midlifeflyer]

This answer contains a bit of speculation. I might even be willing to bet on it, but not with much money. Not much more than an (semi-) educated guess.

Well, you clearly have a situation in which you have a Standard T GPS setup, but without TAAs.

The TKK one is actually easy to explain. If there is no PT depicted o the chart, you don't have to fly one. (Also, note the NoPT in the plan view)

For the GUM approach, I know that from time to time TAAs are not put into place for operational, rather than terrain, reasons. There might be some reason that, unless you are being vectored to the final approach course, the PT is wanted. What it might be I can't even guess. Maybe the reason is uniform to the entire Pacific Chart Supplement area.

I guess the follow up question to:

I can assure you that Guam Center would be less than happy if you started spinning around out there without telling them.

is "Would Guam Center give you a non-vectored approach clearance that brings you to WABOX?" Maybe there is some reason that they would not.

 

[dhc8fo]

Referencing GUM

If you are coming into the approach straight in (ie from the east as you have described), then you will likely be established on the final prior to the IAF. The procedure turn exists to establish you on the final approach course so you would only use it coming in from the west unless you were being vectored to final or if for some reason you weren't established prior to the IAF coming in from the east). It is just like a VOR approach in that respect.


I don't think you are going to find anything that "quote-unquote" says that in the AIM or the FARs exactly, you do have to glean it.

I fly RNAV approaches in this fashion and I stand by it...I am a CFII and I teach it that way. I wouldn't be scared to defend myself to the FAA for it, but you have to make up your own mind. Plus, as someone stated, you may have some special OP SPEC that requires you to do so regardless (I find that hard to believe, personally, but I have heard/seen stranger things).