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Cleared for an approach - Can you descend and when?

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Cleared for an approach - Can you descend and when?

Old 13th Jul 2021, 19:47
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Cleared for an approach - Can you descend and when?

Let's say you are flying at 5000' or descending to 5000' on a STAR.
Controller says: "You are cleared for an ILS approach" (it can be any type of approach).
You take a look at the chart and notice that the published approach altitude is 3000' (both IAF and FAF are at 3000').

1) Can you stay at 5000' and intercept the glide from there?
2) Do you have a right to descend to 3000'?
3) Do you have to descend to 3000'?

Local regulations may differ from country to country.
I am seeking a general world-wide rule that could be proven by legal document.
Please ONLY reply with a reference to an ICAO document.
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Old 13th Jul 2021, 21:30
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You're cleared to 5000 until you're on the published approach, then you can go lower. Ref: ICAO DOC 9585
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Old 14th Jul 2021, 05:10
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ICAO Phraseology Reference Guide states :
"APPROACH AND LANDING
Pilot-interpreted Approaches (eg ILS) Phraseology
The phrase ‘cleared ILS approach runway xx’ has, in the past, introduced
some ambiguity whereby pilots have taken this to mean they are cleared to the
altitude/height depicted on the approach chart immediately prior to the final
approach fix. This should not be assumed; normally clearances to descend at
this point will be given distinctly.
Other phrases that are commonly in use include:
‘Report established localiser (or ILS, GBAS/SBAS/MLS approach course).’
‘Maintain (altitude) until intercepting glide-path.’
‘Report established on glide-path"
So it means that you're unable to des without clearance. There were a few reprts from Chinese CAA about the situation the same as your example.
IAF to IF 900м , FAP at 600m during turn to final the flight crew recived "cleared ILS APCH RW..." and descended to 600 w/o instruction to des. The result was a report from CAA. As I know in the U.S. and in countries that also respect U.S. rules ( South Korea for example) it is permitted to des. as published when you recieved Cleared ..Appch.
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Old 14th Jul 2021, 07:01
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If flying a procedural approach then logic would dictate that you descend in accordance with the published procedure once cleared for the approach. Otherwise you would end up above the glide. If you are being radar vectored then don't descend until positive clearance to do so has been received. Sorry, no ICAO reference.
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Old 14th Jul 2021, 10:01
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My company published such a guidance in OM-A:

When following a standard instrument approach procedure, the altitudes prescribed in the procedures must be adhered to. Descent to the next lower altitude must only be made after passing the relevant fix and provided the aeroplane is following the track specified in the procedure.
When not following a standard instrument approach procedure and cleared for approach but not for any specific altitude (e.g. following a radar vector or a direct-to intercept the final approach track), descent to the next prescribed altitude of the procedure may only be made under following conditions:
- the flight crew has to assure terrain / obstacle clearance is safe and
- the aeroplane is established on the final approach track.
When conducting a visual approach descent below minimum flight altitudes and reduced terrain / obstacle clearance may be accepted.


In your scenario I would maintain 5000 ft until IAF and then follow the published profile.
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Old 14th Jul 2021, 10:35
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From InFO11009 of 3/28/11
Discussion: What this means to pilots is that on some approaches, outside the Final Approach Segment, on a cool day, you might be able to follow the glide slope and all the published stepdown altitudes may pass below your aircraft. The next day, after a warm front passes, you could follow the same glide slope and (because the temperature is hotter this day) those same stepdown altitudes now protrude into the glide slope and require pilot action to ensure compliance with the published minimum altitudes (stepdown fixes). On both days your flight path on the glide slope was the same, but on the hotter day, the stepdown altitude, crept up into your glide path. High barometric pressure produces the same effect as high temperature. Regardless of cause, pilots are cautioned to adhere to published step-down fixes located outside the Final Approach Segment on an ILS approach. If a pilot elects to follow the glide slope while outside the Final Approach Segment he should be fully aware that this technique needs to be closely monitored and, if necessary, action must be taken to meet all stepdown altitudes. Examples of airports where multiple altitude deviations have occurred include, but are not limited to; LAX, ORD, ATL, SLC. Recommended Action: Directors of safety, directors of operations, chief pilots, fractional ownership program managers, training managers, and operators of aircraft should ensure that aircraft under their control, when cleared for an ILS approach, do not descend below published step-down altitudes on an ILS final approach course, while outside the Final Approach Segment.
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Old 14th Jul 2021, 12:02
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1 Dec, 1974.
TWA514, a B727, diverted from KDCA to KIAD and was being vectored at 7,000 ft for a VOR approach to runway 12.
When the controller cleared them for the approach, they descended to and levelled at the FAF altitude of 1800ft.
They then flew into Mt Weather, about 20nm from the runway.
The accident report is worth a read, as existing misunderstandings between ATC and pilots regarding clearance terminology were uncovered and corrected.
To summarise, being cleared for an approach does not imply a clearance to descend from your current altitude, unless in accordance with a published route segment or as a part of further radar vectors.
As a result, since then, US ATC often say something along the lines of, “You are (distance) from (waypoint), maintain (altitude) until established, cleared for (approach type) to (runway).”
As several US lawmakers were killed in the crash, it served as a catalyst to develop the GPWS system.
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Old 14th Jul 2021, 12:14
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Doc 9585
Agreement on the Joint Financing of Certain Air Navigation Services in Greenland (1956) as amended in 1982 and 2008

I was unable to find any relation of this document to the subject.
Please double check the doc's name/number. Thanks!
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Old 14th Jul 2021, 12:22
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eckhard

It's clear that you are not allowed to descent prior to reaching IAF.
But once IAF's been reached, pilots behave differently: some descend, some don't, some say it's a huge violation... and none of them can refer to a document!
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Old 14th Jul 2021, 15:33
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The information you seek might be in PANS OPS or ICAO Annex 14 (?)
Essentially the message is that the crew hold responsibility for terrain clearance irrespective of what ATC ‘suggests’; poorly phrased ATC messages can imply approval which biases the belief of safety.
Do not descend early .

Examples:-
https://www.icao.int/safety/fsix/Lib...plus%20add.pdf
N.B. incident 8
”ATC may have issued an early ‘visual’ approach clearance which was misunderstood as a clearance for further descent to 4300ft, (which is only safe within 9.3nm).”

Last edited by safetypee; 14th Jul 2021 at 15:46.
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Old 14th Jul 2021, 16:23
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Barankin

On the accident you quoted, they were not on a published route. But if you've reached the IAF, you're on a published route.
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Old 14th Jul 2021, 17:15
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@vessbot - are you replying to safetypee, or to eckhardt, or to Barankin (who has not "quoted an accident?"). Your transmission is garbled.
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Old 14th Jul 2021, 23:09
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Barankin

Indeed, as you say, you should not descend prior to reaching the IAF. Out here, ATC sometimes specify it in the transmission "Upon reaching YXX VOR, you are cleared for the .... approach/ upon reaching DUBAG waypoint, you are cleared for the .... approach". Even when this is not the case, it is implied that before reaching the actual approach you are only "pre-cleared" for it and the clearance only comes into effect once you reach a point which is part of the approach (usually an IAF). Therefore, before reaching it, you should maintain the last assigned altitude.

Once the IAF has been reached, there is no need to refer to any document except the approach plate. It will show you exactly how much you can descend on each leg. You can intercept the glideslope (whether actual, virtual or calculated) from "underneath" by maintaining altitude until you start to close in, or you can descend to the minimum altitude for each segment. Usually it's the first option, but depending on the type of operation, on the approach itself and on other circumstances, you might go down the steps instead. Or a combination of the two. In both cases, you must ensure that you are above the relevant minimum altitude. There are exceptions to this - for instance, there are ILS approaches on which the glidepath will briefly dip you under the minimum stepdown altitude at the FAF - but that's where that altitude restriction ceases to be applicable anyway, so it's not really an issue. Otherwise it wouldn't be designed that way.
All that being said, if the minimum altitude over the FAF is 3000' and it was also that at the IAF, as in your example, you naturally wouldn't descend between them.

If your question is whether it is a huge violation to descend below any minimum altitudes, that is another discussion. Is that what you meant?

Last edited by Stuka Child; 14th Jul 2021 at 23:46.
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Old 15th Jul 2021, 05:54
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Originally Posted by Stuka Child View Post

Once the IAF has been reached, there is no need to refer to any document except the approach plate.
I never asked/suggested to descend prior to reaching IAF.
Nor did I asked/suggested to ever descend below a minimum alt before establishing on the glide.

There must be an ICAO document that describes (in details) what pilot should (or can) do upon reaching IAF with no additional instructions from ATC (and flying higher than published minimum alt for that segment).
I was unable to find such ICAO document myself and asked the other pilots to help me find it.
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Old 15th Jul 2021, 08:08
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40 odd years in Aus, NZ and Pacific Islands and have NEVER been cleared for an approach without also being cleared to the (or below) charted altitude for the approach. If it’s different in other parts of the world then ambiguity exists. Query at the time, follow up with written incident report, and an email to the chief pilot or fleet manager for a definitive answer, and keep at them until you get one, and make sure you keep it somewhere that it can’t be lost, deleted, altered or otherwise made not available to you should you need to mount a defence at some time. Same goes for any other issue that causes head scratching.
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Old 15th Jul 2021, 09:04
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Quite usual in my part of the World (EASA Land). Usually a shortcut on the STAR to the IAF and descent to the lowest altitude on the star which is the same as the IAF (12DME) crossing alt (3000’ish). The ILS “platform”altitude is 1800’ so basically from the IAF, it becomes the pilots choice when to intercept Glide Slope, 3000 or 1800. No word from ATC about it. The area is protected both upwards (from other traffic) and below (terrain).
ICAO reference? No idea.
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Old 15th Jul 2021, 13:05
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additional step down altitudes…

May be factored by work load. Traffic load, radio congestion, etc. my experience in Europe, if i’m cleared for the approach, and I’m on a published portion of the approach, I’m taking the approach and descending as published. Specific event, Bergamo’s ILS 28 has an extended downwind procedure with several step downs. There were thunderstorms in the vicinity and the frequency was blocked by, let’s call it, enthusiastic exchanges in the Italian language. Which I do not understand. Happens quite often in Italy whenever weather is intense.

if cleared for the approach, and you’re on a published portion of that approach, it’s no different from a radio failure event.
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Old 16th Jul 2021, 10:00
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ATC clearance for approach means you are cleared for the whole thing as published. Not only all the way down to the runway but also up all the way up to the missed approach altitude. The R/T failure case is a great teaching tool to clarify the responsibilities. Observing any lateral and vertical limitations that form the procedure remains vital. Obviously, ATC's approval does not remove the pilots' responsibility here.

Real-life might bring few scenarios that are not perfectly clear, asking for verification is good airmanship (doing the homework and not asking all the time too). Already mentioned is the classical case of being vectored off the published track, higher than the published intermediate altitude, followed with: "Turn left HDG 220, intercept the localizer. Cleared for ILS approach RWY 18."

Asking your self "Which altitude profile does the ATC have in mind for this?" is very prudent. Belt and braces avoid paperwork. That is why in the UK such clearances are not issued at all and an alternative way of explaining more clearly what the controller needs is provided.


Barankin The emergence of different phraseology to remove ambiguity for this particular scenario proves the baseline Annex 10 standard is not sufficient. Whenever you are given such instruction I would at least inform the ATC before leaving the last cleared level unless it's with the glideslope.

The answer to your dilemma is (also) in the first sentence of this post. Not the ICAO you asked, but what you need.

Annexes are technical specifications, not schoolbooks although PANS-OPS Doc 8168 has some nice recipes. This is a good analogy: You are looking for a recipe on how to fly it, whereas ICAO standards only provide the shopping list and cooking duration with target temperatures. You are looking at the wrong place.

Your reply to Stuka Child at #14 suggest perhaps the advice from him was not well understood, yet he's perfectly right exactly in the part you quoted. Maybe something got lost in the translation?

Last edited by FlightDetent; 24th Jul 2021 at 04:47.
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Old 23rd Jul 2021, 19:23
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Originally Posted by Barankin View Post
I am seeking a general world-wide rule that could be proven by legal document.
There is none.

The example you have given is an example of such a shoddy ATCmanship that the clearance as given is unacceptable. So you really have only one option:

4) clarify the descent clearance with ATC.

It might be novel to some of your KBCs, but one does not incur the wrath of Perun, Mokosh or Veles by simply asking the "диспетчер" to explain what exactly she meant.
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Old 24th Jul 2021, 03:02
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Cleared for the approach…

All well and good to confirm a previous approach clearance. if you can, but try that in Rome or Milan when the area is full of thunderstorms. You will get ONE clearance for the approach in English. Take it. The rest of the frequency space will be full of shouting in Italian. If you are on a published segment of the IAP, and have been cleared for the approach, descend according to the procedure.

The best you have is ICAO. An approach clearance is a clearance to fly the published approach.
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