Menu Sign In Contact FAQ
Welcome to our forums

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

The answer must be NO but it is obviously ambiguous.

The scenario is that you are being vectored to the LOC. You cannot intercept it unless “cleared” for the approach. If not “cleared” then you must fly straight through it.

The other day, coming into EDNY, I was given a heading and told it was “base leg”. But the man (Swiss Radar) didn’t say “cleared for the approach” until the LOC was half scale, which was too tight. I knew where the LOC was (I fly an ILS with a DCT to the runway and with OBS set for the LOC bearing, so I have a magenta line showing me where the LOC is) and had my finger over the APR button on the autopilot.

I bet you could confuse the hell out of a lot of people with “base leg” and have them intercepting without a clearance. OTOH the ATCO would probably not report it because it would show up his mistake.

Shoreham EGKA, United Kingdom

I have little experience in this compared to others, but when I have been vectored, ATC have said turn heading xxx which will take you onto base leg, report localiser established, which assumes you will make your own turn onto finals. I will be honest if I didn’t have that instruction, and the ILS CDI was beginning to move in and I wasn’t being given a new heading to turn, I suppose my instinct would be to request permission to intercept the localiser. If I wasn’t able to get that request into ATC because of other communication I fear I might just begin the turn anyhow – but as you say you shouldn’t as you haven’t been cleared – though it’s probably ATC’s mistake, however it could have been intentional.

OK… this is getting clouded by the old UK practice of using the words “report localiser established” instead of “cleared for the [approach]”. That used to be done because once you are cleared for an approach, you are entitled to descend, at your discretion (and subject to the MSA – that’s another discussion) to the published platform altitude of the IAP. And the UK did not like pilots descending on their own…

The UK stopped doing that some years ago. I don’t recall if “report localiser established” is still used (I think it is) but they are supposed to clear you for the approach formally.

Shoreham EGKA, United Kingdom

It’s just an explanation to you why he is turning you that way at that point. Unless he clears you for the ILS or to intercept the localiser, you are supposed to continue on the last assigned heading until you either run out of fuel or hit terrain (*) or other traffic… (this is common ICAO standard). There are some exceptions like EDDM with parallel runways and heavy (radio) traffic where you are supposed to capture the localiser on your own after being vectored to it at a closing angle. But this is individually described in the relevant AIP/Jeppesen section. In case of an exhibition like AERO it could also be NOTAMed that self-establishing on the ILS is expected after radar vectors.

* sadly, no joke: sometime in the 1990s, a Metroliner flew into the mountains in California on his last radar heading minutes after the controller forgot about him.

Last Edited by what_next at 13 Apr 09:51
EDDS - Stuttgart

In almost 15 years of IFR flying in Europe, I have received that “base leg” addition to a vector maybe five or six times. That speaks works for how much “standard R/T” that is. It means exactly… nothing.

Frankfurt (EDFZ, EDFE), Germany

Again in the UK if they are intentionally flying you through the localizer they are supposed to say so (IME and IAW CAP413)…again I would assume this is the case in Germany?….in the absence of an explanation, say “for spacing”, I would ask….but if unable due to frequency congestion I would stay on heading in the absence of a clearance…

EGPD / OMDW / YPJT, United Kingdom

…again I would assume this is the case in Germany?

If he has the time to tell you, he will do so (“…taking you through the localiser…”). But if he is busy with other traffic or phonecalls, he might not. As we know since the collision at Überlingen, approaches into EDNY are handled by a large sector controller at Swisscom who also has enroute traffic at all levels. But that was most probably changed since then, hopefully.

That speaks works for how much “standard R/T” that is. It means exactly… nothing.

It is indeed standard RT: Traffic permitting, controllers are supposed to give pilots a brief explanation (for which most often no standard phraseology exists) for every deviation from standard. I often fly to EDSB with IFR students. That airspace is within German borders, but managed by a French ATC sector. They will give you a reason for every single radar vector there, without exception. And flying a faster aircraft that needs to be configured at various stages at certain distances from touchdown, you really come to appreciate these “base” or “downwind” hints from the controller, because otherwise you have no idea what his intentions are. I guess I get told things like “base” on 90 percent of occasions anywhere in Europe.

Last Edited by what_next at 13 Apr 10:20
EDDS - Stuttgart

I see ‘base leg’ as nothing more than an awareness thing. To me it certainly doesn’t have anything to do with whether or not you can intercept the loc/ils.

I regularly have to remind the controller and ask him if I am cleared for the approach. In some cases the controller would let me fly through the centerline and would line me up for another intercept and only then clear me for the approach.

EHRD, Netherlands

…and ask him…

This is the best approach to anything flying related once airborne We pay these guys a lot of money to look after us while we fly (through taxes and/or airway fees) and they are there to help us, not the other way round. In all those years, I have never been treated badly by any (IFR) controller anywhere, no matter how stupid the question was.

EDDS - Stuttgart
45 Posts
Sign in to add your message

Back to Top