I agree with you in the respect that it's better to ask ATC for EXACTLY what you want, and confirm with them if there is any question or confusion.

However, I am addressing the OP's question regarding the clearance he got, not what else he might have requested. So far it appears that only Canada has the written procedure for what he thinks he wanted to do...

DANGER, WILL ROBINSON!!!

Don't forget that, in the US at least, ATC is no longer liable for their mistakes, including failure to correct pilots for wrong readbacks. Per an FAA publication a year or 2 ago (I forget the formal title/doc number), pilots are still liable for certificate action if they "break the rules," even with ATC's implicit consent.

BOAC

Well, here's a story that might illustrate why you would "maintain last assigned altitude until on a published segment". Inbound to NAS Rota, Spain (LERT) in the vicinity of the Martin VOR and in cloud, I was attending to physiological needs and didn't hear the clearance, but when I returned to the flight deck of the C-5, we were descending. It seemed a bit early to me, so I asked what altitude we were descending to and why so early. The two other pilots said Sevilla cleared us direct to Rota, descend to 4,000, report leaving FL70. I didn't like going down so early and told them to climb back to FL80, our last assigned level. Just as the words left my mouth, the GPWS sounded, "Terrain, Terrain". We climbed, I informed ATC that we would maintain FL80 until Rota. I also asked what the minimum instrument altitude was for the area and never got much of an answer, let alone an actual altitude.

Lesson: never, ever descend when off-route without being absolutely sure of the terrain. And then don't!

GF

galaxy - what on earth was the point of that post? To tell me you had some muppets in the USAF? I knew that, I met some. I also met a lot of the good ones.

Quite honestly anyone who does what they did should not have been in the seat...and your last phrase was ridiculous!

BOAC

The point of the post should have been apparent in the first sentence--do not descend without knowing the terrain and your clearance. The OP was in EXACTLY the same position--direct, off-route to a fix except he only had FL80 as a level clearance, no specific descent clearance from ATC and no published route. My two muppets had an altitude clearance that was NOT appropriate for the terrain or distance from the field, but acted on that clearance, wrongly but the controller didn't give them any help.

My guys did 'declare' leaving and did get an acknowledgment, hardly a safe and efficient.

Given that clearance to 4,000 feet by the controller, how was a crew supposed to know it would not be safe to descend? It was a bad clearance on the part of ATCO and bad airmanship on the part of the pilots.

As Intruder and I have been saying, published route or maintain your altitude or level until on one.

My two were summarily unqualified--one never to be an commander.

If my last sentence is "ridiculous", it is only because it rules out ANY descent when off-route which is a bit extreme, I suppose.

GF

Old Smokey* once gave advice that I now hold very close to my heart, in fact it is one of the best pieces of advice I've ever seen...for the air or ground


'Trust Nothing; Trust No One":suspect:


GF's post has a very important moral to it...CFIT has not died even with EGPWS







* where've you been?:)

One other point.....

Like lawyers, we have been batting this problem around for 4 pages, at our leisure. The Original Poster should NOT have been left in doubt what altitude to fly, in a speeding airplane, possibly over hazardous terrain. If the ATCO had issued this clearance, "Cleared direct to KELON, cross KELON at or above 2,500 feet (or whatever is appropriate for the case), cleared ILS 10", it would have been crystal clear what altitude to fly enroute to KELON.

TW 514, to any pilot in the US that remembers it, was one of the real influential accidents--it changed aviation. GPWS and EGPWS comes directly from that accident, as does a slew of FAA ATC changes, radar low altitude warnings and CRM. As I remember it, the FE was on the tape protesting the pilots decision to descend to the intermediate altitude when cleared by Approach Control.

There are lots of "out-of-the-way" airports where a clearance like the OP's and a descent based on the clearance could kill. The American and Canadian West have many such airports; no doubt the Alps, too.

GF

galaxy flyer:

Alas, he didn't really protest, rather he questioned the altitudes on an IAP chart that did not meet U.S. chartings specifications (which required that the intermediate fix be in the profile view.)

I knew the captain quite well. <sigh> And, I was an ALPA rep on that seeming never-ending investigation.

You're right, that accident was a "deal changer," which included ICAO as well as the U.S. But, 35 years has passed so the wheel will likely be invented again, so to speak.

a bit of editing, merging and moving to tidy up. Unfortunately, this post ended up by me rather than the intending poster (76mike) .. apologies for the finger trouble on my part .. JT


Sorry; I'm still confused. Do we have a consensus on a reasonable answer for the VERY IMPORTANT question (and thread) "Descending once cleared for the approach"?

If I may restate the question: Say you're at 8000 feet. And the controller has told you to proceed direct to ABC VOR, and has cleared you for the approach. Also, say he has omitted an altitude to maintain. Finally, the approach plate says cross the VOR at 2500 feet.

When do you leave 8000 for 2500? Yes, we could ask the controller. Yes, we could be conservative, cross the VOR at 8000 feet, and then descend. However, in lieu of these two options, is there a "Textbook" answer?

Much thanks,
Mike

Well, imho this discussion indicates that there's a question for icao, fsf: why we still don't have clear international procedures regarding the matter?:ugh:
Cfit, alar - that's fine but we have 4 pages of discussions on such a simple and live question:sad:

Presumably for the usual, mundane reason that ICAO's members do not all agree on those procedures. As has become clear through contributions in this thread.

PBL

- yes - amazing. Since we are forced to live in an imperfect world, ask (as per post #8). So simple - you don't need PPRune or ICAO or any other system. Just a mouth and a radio (an an ear to hear the reply of course). Countless times I have been given an ambiguous clearance. Either I know where I am and what is underneath me or I don't. Case 1 full procedural into the hold. Case 2 - you say 'Henri - am I clear unrestricted descent?' All the theoreticians and rule makers can take all the time in the world romanticising/sematicising over this, you have an aeroplane with limited endurance. It's called 'airmanship'. (Or was:ugh:)

Hi BOAC,

I agree totally.

Using Airmanship: when within 25 dme CAV, request descent to an Altitude above MSA say 3,000 feet initially. Then establish straight towards Kelon, descending as appropriate iaw MSA / procedure.

see page 5 for ILS App @ Chalons VATRY

There are quite a few issues causing confusion here and if they are removed then I think the solution is easy.

1. Bookworm spoke about the UK practice of ATC not using the phrase "cleared ILS". This highlights a misunderstanding on the Pilot side.

Remember that when Approach radar are vectoring the aircraft towards the ILS, the aircraft is in the initial approach phase - the vectors are replacing the procedure turn, base turn or other procedure designed for the initial phase and once established on the LOC it is in the intermediate phase and when it intercepts the glide path (at whatever altitude within the glidepath covereage) it is in the final phase of the approach.

Therefore that situation is not the same as the one described in the original post becasue in effect when put on the 30 degree leg and told "cleared ILS" the aircraft is already on the initial approach leg (in effect inside the IAF) and by definition can (and should be safe to in terms of terrain) descend to the intermediate altitude.

That is not the situation here.

2. A clearance has a start point and an end. In this case the clearance "cleared ILS Z" while enroute to the IAF ony has effect when the IAF is reached. This seems to not only be a problem in the arrival phase but has also caused problems enroute where for example aircraft within domestic airspace have received an oceanic clearance at say FL380 and have incorrectly climbed while in domestic airspace to FL380 without ATC clearance. So every clearance has a start and a finish and one can not pre-empt the start.

In this case, the aircraft was cleared to proceed from the IAF through the procedure all the way to the missed approach holding fix. Anything before the IAF was a separate issue.

3. Everyone is having a bit of tunnel vision with regard to MSA and terrain issues. What about other traffic and airspace issues. In terrain terms is may be safe to descend to 2500ft but will that cause the aircraft to leave controlled airspace, enter a restricted area or conflict with other traffic?

I would be interested to know what the inbound track to the IAF of the original poster was.

The only safe option in this case is to request descent when appropriate because "cleared ILS" being issues to an aircraft while enroute does not mean they can descend straight away.

Until the aircraft is established on the procedre then any levels approprioate to that procedure do not apply.

To exactly the same extent as the "direct to KELON" clearance replaces the arrival segment.

If you believe that "cleared ILS" permits descent to the intermediate altitude, why do you not believe that the "direct to KELON" permits descent in accordance with the arrival?

BOAC
I absolutely agree - ANY DOUBT - ASK.
But we have similar situations every day, they have to be clearly defined in international, not British or US regulations.

P.S.
from personal experience in ZBAA
ATC - niauoirjvnb....
P - say again, please
ATC - ffjvbriogiu...
P - say again?
ATC - rtoihyihjk...
P - confirm clear to land?
ATC - affirm!
P - thanks!:ok:

- for 'have to' I suggest 'should be', and the point I am making is that when things are not clear, clarify and if that is still confusing and you are really not sure, then stick with a procedural approach. We cannot expect a perfect harmonised world.

In your quote I assume all you needed was clearance to land - you clarified and got it.

"Cleared ILS" when being vectored is given at a suitable point in the procedure where the flight has been placed correctly by the ATCO on an intercept with the intermediate phase of the approach and is in a position to descend to the level appropriate for the start of that phase (note that it is normally a level phase).

I never cease to be amazed by the number of pilots who are being vectored at 3000ft by ATC and on the 30 degree leg at 13nm are "clerared ILS" which triggers some irrational desire to dive as quickly as possible to 2000ft (the published platform level) despite the fact that they can establish on the LOC and have the required 2nm of established level flight before GS intercept - at 3000ft!!!!


Cleared direct to KELON is a lateral clearance alone and for example just because the minimum level on fro example an airway to KELON (which could be your IAF) is 2500ft you are most certainly not cleared to 2500ft simply becasue the ATCO cleared you to KELON.

As I pointed out - yes it is terrain safe and in this case it would be airspace safe (probably) but is it safe against opposite direction traffic then only ATC knows and they have not cleared you to change level.

When in the procedure eg in the case cited in the hold or at the IAF at FL80, ATC can not clear you for the procedure unless there are no other flights below you in the procedure. However, when 20 miles away inbound from say the south east at FL80 they can clear you to the IAF and clear you for the approach (becasue the procedure is empty) but climb a departure to FL70 straight at you.

They have issued you a clearance for the ILS procedure. They have not issued a clearance to descend until on that procedure.

Yes FL80 is very high to start the procedure and would perhaps be uncomfortable if doing it direct and not via a shuttle. However, until ATC clear you lower (which they may have planned) you do not know that it is safe to do so.

I will repeat that;

until ATC clear you to a lower level you do not know that it is safe to do so

Safety first.

do not bother to ask ATC for clarification - it makes too much sense.

do not use initiative, regulations and procedures are a preferred substitute.

before 25 miles, the concept of maintaining any altitude in excess of the lowest en route FL or altitude makes too much sense, as it is likely to avoid premature contact with terrain.

when inside the 25 mile MSA do not, descend down to the safe altitude, it is likely to make the approach segment and aircraft configuration too easy to manage

if it is possible to find a longer and more complex way of achieving the task of a straight in approach, explore all options, then you can write about them on PPRuNE

The entire point of this thread is about whether a clearance to a lower level is implicit in a particular clearance phraseology.

And one can equally argue that:

"Cleared ILS" when on a ATC-initiated direct segment to KELON is given at a suitable point in the procedure where the flight has been placed correctly by the ATCO on to commence the initial phase of the approach from the IAF and is in a position to descend to the level appropriate for the start of that phase.

So if ATC has cleared me to an on-airfield IAF at 4000 ft above the airport and then uses the phrase "cleared visual approach", do you think that I'm required to fly to the IAF at 4000 ft before commencing descent on the visual approach?

As several posters have pointed out, the safety that you desire comes from clarity about the interpretation that should be placed on particular phraseology. Accidents come from situations where ATC and pilots interpret the same phraseology in different ways and circumstances prevent a timely clarification.