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Is "base leg" the same as "cleared for the ILS"?

Peter wrote:

The other funny one was that the last descent was to 2000ft, not the 1500ft ILS platform.

This is particularly annoying when the GS is U/S and they are LOC only, but the controller forgets that, and clears you to a higher altitude (as normal for a full ILS) so you don’t notice that you are high at the FAF or the CDFA. Been there, done that :-(

EGKB Biggin Hill

Yes a quick “Confirm cleared ILS runway x?” should do the trick.

EKRK, Denmark

Peter wrote:

The other funny one was that the last descent was to 2000ft, not the 1500ft ILS platform.

I always double-check in cases like this whether I’m cleared to descend to glideslope after establishing on localizer if not clearly said to avoid ambiguity.

LDZA LDVA, Croatia

I got a funny variation of this today, at EGHH.

I wish I had it recorded. It was a vector towards the ILS, with an instruction like “turn left xxx for the ILS”.

It was obviously a clearance to intercept the LOC, but no “cleared for” was used. Interesting…

They have also finished using the “report localiser established” followed by “descend with the glideslope” which was commonly used.

The other funny one was that the last descent was to 2000ft, not the 1500ft ILS platform.

Administrator
Shoreham EGKA, United Kingdom

Here in the US, an MSA is not an operational altitude. One may not descend until on a charted portion of the approach or airway leading to the IAF after having been cleared for the approach. This rule was paid for in blood as are many others.

KUZA, United States

If you consider an airfield with movements in and out every few minutes, with a platform altitude of 2500’ and an MSA of 3500’, how would you want them to descend if cleared for the ILS at say 5000’?

Exactly the same way it is done everywhere else on this planet.

EDDS - Stuttgart

their manuals only permit “cleared for the ILS” whenever you are already at platform altitude or lower.

That is actually very plausible. I think that is how the UK works this i.e. the “clear for…” phrase is used only after they somehow got you down to the platform altitude.

I suspect most airports around the world do the same, because if say the platform is 2000ft, the MSA is 4000ft, and you are 20nm away, what should you do?

If you are being vectored then ATC is responsible for your obstacle clearance (except in some places, like Spain ) so the situation should be resolved by itself.

If you are not being vectored then it is still in ATC’s general interest to not kill you (crash = a lot of paperwork). But they cannot see you “officially” unless they have official radar and the ATCO is an official ICAO radar qualified ATCO. So various procedures have to be used to solve this.

In the above example, non-vectored, the simplest always-correct way is to fly to the holding fix (the one above the airport) and descend in the hold from 4000ft to 2000ft and then fly the approach. Or some similar procedure at/near an IAF. For anything else you need terrain awareness, which in “classical IFR” the pilot does not have, and arguably should not need, ever, if classical IFR procedures are followed.

Last Edited by Peter at 14 Apr 15:37
Administrator
Shoreham EGKA, United Kingdom

I often fly into an airfield in the UK that maintains the “Once established descend with the glide” phraseology. I had a chat with them about this one evening on the ground whilst discussing another issue, and their manuals only permit “cleared for the ILS” whenever you are already at platform altitude or lower. The reason it is rarely heard at this airfield is because the Minimum Radar Vector Altitude only allows them to descend you to platform altitude whenever you are very very close to the FAP. I would think that pilots should have enough wit about them that if they were going into this airport and were cleared for the approach 25nm out, they wouldn’t descend to platform straight away cos they are going to put themselves closer to terrain than I am sure they would like, but then I suppose you have the problem of how you expect someone to descend.

If you consider an airfield with movements in and out every few minutes, with a platform altitude of 2500’ and an MSA of 3500’, how would you want them to descend if cleared for the ILS at say 5000’?

United Kingdom

I don’t fly enough ILSs in the UK but for the last few years (that I remember) I was always “cleared for the XX approach”.

One tends to get the “report localiser established” or “report final approach fix” on an RNAV approach, etc, on top of that.

But the “cleared for the XX approach” is a full standalone clearance, adequate all by itself, and entitling you to go all the way down to the runway but not touch it (for that you need “cleared to land”).

So if, after being cleared for the approach but asked to report at X miles etc, you have a bunch of people reading out War and Peace (which is normal in the UK on any nice weekend day) you can go all the way down to the runway (but not touch it).

Administrator
Shoreham EGKA, United Kingdom

@PiperArcher – all over, my home base doesn’t have an instrument approach. The terminology seems to be fairly standard.

EGLM & EGTN
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