When to descend on an RNAV approach

TangoWhiskey

TangoWhiskey

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4,000 until UDUZI; until you pass UDUZI, you are not established on the approach.

It is a significant amount of altitude to lose in a short distance, so you might request lower.

edit: After reading the discussion, I'll be interested in seeing what result we get from the folks, here, whom I trust. I just do not believe that the intent is to treat the mere presence anywhere within the 30nm TAA as "established" on the approach.
 
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I'm with Spike... 4,000 until UDUZI, then 2,000. I understand the argument that if you're in the TAA you're established on the approach so you can descend to 2,700, but I wouldn't fly it that way. I've always thought that being established on the approach involved flying a published segment of that approach. In this case I'd query the controller and ask for lower to cross UDUZI at a reasonable altitude.

I'm curious as to what the CFII's have to say.
 
I agree with you, Spike. Chip, the only part I disagree with in the arguments those folks make is 'if you're in a TAA you're established on the approach so you can descend to 2700'. I agree with what you said--you have to be on a published segment of the approach to be "established" on the approach.

What I find "interesting" (and SCARY) is that we have IFR pilots out there that don't get this, and would descend early. If I were crossing NW to SE under IFR, at 3000', and you decided it was okay for you to descend from 4000 to 2700 just because you're inside of 30 nm of the fix and your GPS has ramped down the RNP scaling, we've got a problem!
 
I agree 4000 until UDUZI. I don't agree that being in the TAA is being established on the approach, it requires a charted segment of the approach.

I would compare it to being on a feeder route. If you are assigned a feeder route and an altitude until "established on the approach" you do not descend to the minimum alitude for the feeder route.

This is from AIM 5-4-7
b. When operating on an unpublished route or while being radar vectored, the pilot, when an approach clearance is received, shall, in addition to complying with the minimum altitudes for IFR operations (14 CFR Section 91.177), maintain the last assigned altitude unless a different altitude is assigned by ATC, or until the aircraft is established on a segment of a published route or IAP. After the aircraft is so established, published altitudes apply to descent within each succeeding route or approach segment unless a different altitude is assigned by ATC. Notwithstanding this pilot responsibility, for aircraft operating on unpublished routes or while being radar vectored, ATC will, except when conducting a radar approach, issue an IFR approach clearance only after the aircraft is established on a segment of a published route or IAP, or assign an altitude to maintain until the aircraft is established on a segment of a published route or instrument approach procedure. For this purpose, the procedure turn of a published IAP shall not be considered a segment of that IAP until the aircraft reaches the initial fix or navigation facility upon which the procedure turn is predicated.
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Joe

Note: I'm not sure my CFI-I rating increases the chances of being right as much as make it much more embarassing when I'm wrong.
 
If asked to fly this, first thing I'd say is "Sorry sir, we're slant Alpha, I'll need a different approach."


Assuming I'm in a plane with GPS, though, I'd say 4k to Uduzi, then drop (quickly) to 2k on the transition to Ugmah, then 1600 after Ugmah. Unless ATC says to stay higher for any reason, the procedure lets you descend to those altitudes at those waypoints...no reason to stay higher when you're trying to get out of the clouds.


You wanna a really horrid approach for having to lose altitude...from Seyco to Kimmy you have to drop the gear and completely close the throttle to get down in time in a Seminole, so of course this is one of the approaches you have to fly for the CFII ride.
http://flightaware.com/resources/airport/KVGT/IAP/GPS+RWY+12R
 
I might suggest one takes a look at the Instrument Procedures Handbook at 5-46. "Procedurally, pilots my be cleared to an IAF associated with the TAA. ATC expects the flight to proceed to the IAF and maintain the altitude depicted for that area of the TAA, unless cleared otherwise. An obstacle clearance of at least 1,000 feet is guaranteed within the boundaries of the TAA." BTW, TAAs are set up in light of traffic conflicts in the area.

Best,

Dave
 
Eckalbar also give a very good explaination in IFR, A Structured Approach at page 79.

"The TAA sector minimum altitudes are now analogous to the minimum altitudes along the old charted routes to the IAF. The entire 30 miles TAA boarder is analogous to a feeder fix. Unless you have been told otherwise, once you are cleared for the approach and inside the right base (his example) TAA, for example, you can descend to a minimum of 5,500 feet (wish is the same as the 2,700 feet on the example approach at SFB)

Best,

Dave
 
Areeda said:
I would compare it to being on a feeder route.
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I found this from AIM 5-4-5 d 9

9. When an airway does not cross the lateral TAA boundaries, a feeder route will be established to provide a transition from the en route structure to the appropriate IAF. Each feeder route will terminate at the TAA boundary, and will be aligned along a path pointing to the associated IAF. Pilots should descend to the TAA altitude after crossing the TAA boundary and cleared by air traffic control. (See FIG 5-4-12).
 
I would ask for a clarification.

If the controller had just said "cleared for the RNAV 9L approach" you could descend to 2700' when within 30 nm of UDUZI. Maybe there was some other reason, like traffic, that they wanted the airplane at 4000'. Or maybe the controller used the wrong terminology. Or maybe we aren't understanding what "established on the approach" means. In any case, I think it's better to ask if you are not sure.
 
Dave Siciliano said:
Eckalbar also give a very good explaination in IFR, A Structured Approach at page 79.

"The TAA sector minimum altitudes are now analogous to the minimum altitudes along the old charted routes to the IAF. The entire 30 miles TAA boarder is analogous to a feeder fix. Unless you have been told otherwise, once you are cleared for the approach and inside the right base (his example) TAA, for example, you can descend to a minimum of 5,500 feet (wish is the same as the 2,700 feet on the example approach at SFB)

Best,

Dave
Click to expand...


Wow, cool stuff Dave. What does TAA stand for here? I presume it's not the usual "techologically advanced aircraft"...
 
Terminal Arrival Area which are addressed in FAA Order 8260.45A Terminal Arrival Area (TAA) Design Criteria. The TAA is that 30 mile arc you see with a published altitude in a rectangle on the chart. The Instrument Procedures Handbook is on line. It's worth a peruse.

Best,

Dave
 
I would not descend below 4000 until on a charted leg, not just inside the TAA. If I felt I was being held too high outside the charted leg I'd ask for lower.

I understand the TAA argument, but to me the possibility of mid-air or CFIT is just too great to make parsing the AIM a worthwhile endeavor. This isn't something I would take a chance on in the real world.

If the controller gets cranky and lectures me about reading the AIM I can live with that.
 
Well, let's skip the "maintain 4000' until established" for the moment, we'll get back to that in a second.

As mentioned already, when an approach clearance is given to an aircraft not yet "established", the controller is required to give an altitude to maintain until established. How does this apply to a TAA? Well, 7110.65R is pretty clear on this.

If the pilot was inside the TAA boundary when given the clearance, the controller would not have to specify an altitude to maintain until established, as the aircraft is already considered established (for the purpose of this requirement, at least) as long as it's anywhere inside the TAA boundary (e.g. within 30nm of UDUZI). In this case, the controller would say something like "cleared rnav runway 9L approach", and have no need to specify an altitude. As soon as the pilot received this clearance, he could immediately begin to descend to the altitude for that TAA sector of 2700'.

If you "don't trust" this 2700' altitude, then I see no reason why you should trust any of the other altitudes on the approach plate. This is "the system", this is how it works, that altitude is just like an altitude associated with a charted segment. The TAA sector is like one big segment, and that altitude covers every possible "segment" you could fly in that sector.

Now, if the pilot was outside the TAA boundary when given the clearance, then the aircraft is not considered to be "established" yet, and so the controller is required to assign an altitude to fly until established. But 7110.65R specifies the phraseology of this as something like "... maintain 4000 until entering the TAA...". After receiving this clearance, the pilot would fly 4000 until crossing the TAA boundary at 30nm from UDUZI, after which he could descend (with no further communication with ATC) to 2700.

Now, what do you do if the controller says "maintain 4000 until established"?

The controller is using non-standard phraseology, this has the effect of bringing his meaning into question. You have two choices:
a) figure he's just not up on his phraseology, and _meant_ to say the right thing ("maintain XXX until entering the TAA"), just fly 4000 until crossing the TAA boundary, then descend to 2700
b) ask for a clarification, because he may be trying to give me an altitude restriction for some valid reason (though, in the real world, I'd expect something more like "maintain 4000 until UDUZI")
-harry
 
gibbons said:
Good stuff Dave. I stand corrected.
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Lots of changes with RNAV and WAAS Chip. I'm not trying to correct anyone; just referring to what the books state <g> .

Ron recently stated one must fly by the IAF on an RNAV approach and a change was pointed out in the AIM which states that isn't necessary with certain caveats; so, you are in illustrious company sir!!

Lance actually briefed us on some of this stuff at SIMCOM last Spring. So, I've hear it, read 'bout it and actually asked an approach controller about it once before gettin comfortable. Us old Infantry guys are used to being told at least three times.

Sounds like you owe me dessert at an Italian restaurant for doin all this research during workin hours! How 'bout some Spumoni with Balsamic Vinegar on top <vbg>

Best,

Dave
 
Dave Siciliano said:
Sounds like you owe me dessert at an Italian restaurant for doin all this research during workin hours! How 'bout some Spumoni with Balsamic Vinegar on top <vbg>
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If it means getting to visit with you and Spike for a while, I'll do it!!! I don't even need to order it. The waiter will bring it to the table and put it on the bill no matter what! :rofl:
 
mantakos said:
...
If the pilot was inside the TAA boundary when given the clearance, the controller would not have to specify an altitude to maintain until established, as the aircraft is already considered established (for the purpose of this requirement, at least) as long as it's anywhere inside the TAA boundary (e.g. within 30nm of UDUZI). In this case, the controller would say something like "cleared rnav runway 9L approach", and have no need to specify an altitude. As soon as the pilot received this clearance, he could immediately begin to descend to the altitude for that TAA sector of 2700'.
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I've never, ever had a controller clear me for the approach without giving some kind of altitude guidance. I'm sure you're correct about what's in the book, my concern is that this particular part of the book isn't really utilized in practice very much, at least not where I fly. Certainly there is plenty of room for confusion.

If you "don't trust" this 2700' altitude, then I see no reason why you should trust any of the other altitudes on the approach plate. ...
-harry
Click to expand...

What I really should say is that I don't trust myself, the other pilots and controllers to not get confused on this point. If I had this question about what altitude to fly I'd get it clarified to be sure that me, the controller, and any other pilots in the neighborhood are all singing from the same book.

Tenerife

TWA 514

AA 965
 
Jim:

Perhaps one of the controllers can clarify phraseology for you. If you read the post above, with RNAV, this area is treated like a segment of the approach. Once the Controller clears you for the approach, you can descend to the published altitude in the TAA. If he tells you to maintain another altitude, you have to do that. The confusion seems to be the 4,000 until established, is that correct?

Best,

Dave
 
RMCN172RG said:
That's how I was taught
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Ray: That's the beauty of RVAV. The ability to go direct. No more choke points funneling everyone in the same way. The TAA area has taken terrain clearance and traffic into consideration in design.

Best,

Dave
 
Sounds to me like the "until established" phraseology is what causes confusion. Most of us are trained that "established" means a nearly centered needle on a published radial or localizer (or equivalent NDB bearing) that is part of the approach course.

As Dave noted, the RNAV approaches with TAAs break down the arrival into sectors, and each sector is a published segment of the approach. A specific course inbound through the TAA might be eligible for a LOWER minimum altitude, but I bet somewhere in TERPS there's guidance that defines when a TAA can be used, and it would consider things like the resulting descent rates if there's a drastic change in required altitudes. So we shouldn't see a TAA approach that requires unusually high descent rates.
 
gibbons said:
Good stuff Dave. I stand corrected.
Click to expand...

Me too! I love this "always learning" stuff. Just read over 5-4-5 of the AIM (again) and found it very educational with respect to TAAs and MSAs and how to tell the difference.

I do have one question on the AIM content shown below. Where it says "cleared to fly the TAA"... do they say "cleared to fly the TAA, RNAV RWY 9L", or is "cleared RNAV RWY 9L" sufficient to fly the TAA altitudes?

From the AIM :

(b) Pilots entering the TAA and cleared by air traffic control, are expected to proceed directly to the IAF associated with that area of the TAA at the altitude depicted, unless otherwise cleared by air traffic control. Cleared direct to an Initial Approach Fix (IAF) without a clearance for the procedure does not authorize a pilot to descend to a lower TAA altitude. If a pilot desires a lower altitude without an approach clearance, request the lower TAA altitude. If a pilot is not sure of what they are authorized or expected to do by air traffic, they should ask air traffic or request a specific clearance. Pilots entering the TAA with two-way radio communications failure (14 CFR Section 91.185, IFR Operations: Two-way Radio Communications Failure), must maintain the highest altitude prescribed by Section 91.185(c)(2) until arriving at the appropriate IAF.

<snip>

6. Once cleared to fly the TAA, pilots are expected to obey minimum altitudes depicted within the TAA icons, unless instructed otherwise by air traffic control. In FIG 5-4-8, pilots within the left or right-base areas are expected to maintain a minimum altitude of 6,000 feet until within 17 NM of the associated IAF. After crossing the 17 NM arc, descent is authorized to the lower charted altitudes. Pilots approaching from the northwest are expected to maintain a minimum altitude of 6,000 feet, and when within 22 NM of the IF (IAF), descend to a minimum altitude of 2,000 feet MSL until reaching the IF (IAF).

FIGURE 5-4-8:

F0504009.gif
 
There was a question here about what the standard phraseology would be. http://www.faa.gov/airports_airtraffic/air_traffic/publications/atpubs/ATC/Chp4/atc0408.html has the reference document. Search that page for "TAA".

e. Where a Terminal Arrival Area (TAA) has been established to support RNAV approaches use the procedures under subpara b1 and b2 above. (See FIG 4-8-3.)

EXAMPLE-
Aircraft 1: The aircraft has crossed the TAA boundary and is established on a segment of the approach. "Cleared R-NAV Runway One Eight Approach."

Aircraft 2: The aircraft is inbound to the CHARR (right corner) IAF on an unpublished direct route at 7,000 feet. The minimum IFR altitude for IFR operations (14 CFR Section 91.177) along this flight path to the IAF is 5,000 feet. "Cleared to CHARR, Maintain at or above five thousand until entering the TAA, Cleared R-NAV Runway One Eight Approach."
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Responding to two different posts...
...I've never, ever had a controller clear me for the approach without giving some kind of altitude guidance. ...
Click to expand...
Have you ever been given an approach clearance after you were already "established"? For instance, have you ever had a controller give you a vector to intercept the localizer and tell you to intercept it, and then issue the approach clearance a little later, after you're established on it? In this scenario, they're not required to give any altitude guidance, they can just say "cleared for the approach". And, really, if they were to give altitude guidance, what would they say?
... do they say "cleared to fly the TAA, RNAV RWY 9L", or is "cleared RNAV RWY 9L" sufficient to fly the TAA altitudes?
Click to expand...
If you're outside the TAA boundary when issued the approach clearance, the controller is required to give you a "maintain XXX until entering the TAA". You'll maintain that altitude until you cross the TAA boundary, then you can descend to the TAA sector altitude on the chart. See "Aircraft 2" in the post above.

If you're inside the TAA when issued the approach clearance, the controller will not give you a "maintain XXX until entering", because you're already entered. Instead, they'll just give you an approach clearance, and you'll immediately be authorized to descend to the TAA sector altitude. See "Aircraft 1" in the post above.
-harry
 
Assuming you're in the sector such that your course inbound to UDUZI is between 185 and 275, 4000 until within 30nm of UDUZI, then 2700 to UDUZI, then 2000 to UGMAH. Ref: AIM 5-4-5d5(b). And the clearance stated in the opening post of the Google thread is not in compliance with FAA Order 7110.65. It should say, "Nxxxxx, cleared to UDUZI, maintain 4000 until entering the TAA, cleared for the R-NAV Runway 9L approach." Ref: FAA Order 7110.65, 4-8-1e, Example Aircraft 2. However, the bottom line is that being in the depicted sector constitutes being established on a published route/segment, and at that point, once cleared for the approach, you are permitted to descend to the published altitude (in this case, 2700).
 
Ron Levy said:
Assuming you're in the sector such that your course inbound to UDUZI is between 185 and 275, 4000 until within 30nm of UDUZI, then 2700 to UDUZI, then 2000 to UGMAH. Ref: AIM 5-4-5d5(b). And the clearance stated in the opening post of the Google thread is not in compliance with FAA Order 7110.65. It should say, "Nxxxxx, cleared to UDUZI, maintain 4000 until entering the TAA, cleared for the R-NAV Runway 9L approach." Ref: FAA Order 7110.65, 4-8-1e, Example Aircraft 2. However, the bottom line is that being in the depicted sector constitutes being established on a published route/segment, and at that point, once cleared for the approach, you are permitted to descend to the published altitude (in this case, 2700).
Click to expand...

I would've disagreed with this before I re-read the AIM and the 7110.65R, but you're spot on. Cool stuff! This is all new to me. Thanks for the interesting thread and education!!
 
TangoWhiskey said:
I would've disagreed with this before I re-read the AIM and the 7110.65R, but you're spot on. Cool stuff! This is all new to me. Thanks for the interesting thread and education!!
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Me too. My inclination was to take the more conservative (but wrong) tack of 4000 until the IAF, then lose 2000' in about 5 NM. Always learning. Thanks!
 
Afterthought: This example shows why it's so important to use the proper phraseology in communications between aircraft and ATC. Eliding in order to sound slicker or speed up the process only creates confusion which leads to misunderstandings or the need to repeat transmissions (thus wiping out any time saved by the first one). If everyone sticks with the applicable books (Pilot/Controller Glossary, AIM, ATC Handbook, etc), then there are no questions as to what something means. If the controller really said what the opening post in the Google thread said s/he did, then fie on that controller for not following the book. If the controller used the proper terminology (and was misquoted by the poster), then fie on the pilot for not reading the book.
 
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