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A question to London Controllers
Hi guys,
been flying in and out of LHR & MAN on a regular basis for a german carrier. Being cleared for an ILS approach in most parts of Europe usually includes actually being cleared for an ILS (i.e. LH 123, turn left/right heading XXX, cleared ILS Approach RWY XXX). I´ve noticed that in LHR & MAN you are usually cleared on a heading and asked to report localizer established. Then a descend clearance is given with the addition to continue on the glideslope. Why is that so? Cheers and thanks in advance! :-) |
This is a UK thing. The CAA has deemed it to be safer to give an explicit descent clearance rather then combining the two into one "cleared ILS" instruction.
The details on this can be found in the UK AIP, under the chapter that discuss UK-ICAO differences. |
It's been the norm for many, many years. Some aircraft which were given "cleared for the ILS" went down far too low over London and conflicted with other traffic. There are lots of helicopters and fixed wing traffic flying under the ILS so it is necessary to provide separation by specifying that you descend on the glidepath..
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And in addition to the above, you may be vectored for the initial part of the approach and given a heading to establish on the localiser by an Area controller (happens a lot for Gatwick) and legally our licence does not allow us to clear you for the ILS...
Cheers, Northerner "Keep smiling, it makes people wonder what you're up to..." |
@Northerner
...legally our licence does not allow us to clear you for the ILS... |
It's been the norm for many, many years. I'm guessing that the starting height for the ILS conflicts with underflying traffic unless you are established on the localiser. |
Pera.. A few aircraft went down to around 1200 feet over London - some 11 miles from touchdown. Lord only knows why they did so but it was before the days of SSR height readouts so ATC was not aware. ATC normally descends traffic to intercept the ILS at around glidepath level, e.g 3000ft at 10 miles, etc. Some crews, having being told "cleared for the ILS" went down immediately instead of following the GP. There's a lot going on under the Heathrow glidepaths which is why the phraseology was changed.
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More years ago than I care to remember, I was No 2 director at Gatwick vectoring an US registered DC10 for a fairly late turn onto the 08 ILS. "Cleared for the ILS" said I, "Descending to 1200 feet" says he. It might have been a slightly different level, but as the aircraft was pointing directly at Leith Hill with a top just under 1000ft and the aircraft had been cleared to maintain 2000ft, the actual level is immaterial. I never used that piece of terminology again.
A I:} |
A I Makes you wonder why so many pilots just don't get it!
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Pera.. A few aircraft went down to around 1200 feet over London - some 11 miles from touchdown. Lord only knows why they did so but it was before the days of SSR height readouts so ATC was not aware. ATC normally descends traffic to intercept the ILS at around glidepath level, e.g 3000ft at 10 miles, etc. Some crews, having being told "cleared for the ILS" went down immediately instead of following the GP. There's a lot going on under the Heathrow glidepaths which is why the phraseology was changed. I don't like to see them do that in a mountainous area. |
@Northerner
Quote: ...legally our licence does not allow us to clear you for the ILS... Just curiosity, where does it say this? Now you've got me.... Not sure! Was always taught that my area ticket did not legally allow me to put the a/c on the ILS as this was a function of an approach rated licence.... Would have to do some digging to find out where. :O:\ Cheers, Northerner "Keep smiling - it makes people wonder what you're up to..." |
The phraesology will be changed shortly to permit the controller to say 'cleared for ILS approach' with one or two constraints, one being that the aircraft must be at platform altitude as shown on the approach plate.
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...legally our licence does not allow us to clear you for the ILS... Just curiosity, where does it say this? Now you've got me.... Not sure! Was always taught that my area ticket did not legally allow me to put the a/c on the ILS as this was a function of an approach rated licence.... Would have to do some digging to find out where. |
As far as I understand TMA controllers are not permitted to descend aircraft below 4000' when establishing the aircraft on the localizer themselves. Not too sure why really.
I would have thought airspace constraints will be getting in the way of going any lower in most cases anyway, except perhaps Stansted 04. Thats considering the aircraft will be establishing pretty far out then transferring to approach. |
rice.and.pea...... Have a word with your training officers and maybe they can help.
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Thanks for all the replies Gentlemen! Some of what I`ve read here makes sense. If you´ve got tossers descending on their own terms than you must use these constraints. I´ve just never considered this as being plausible as for me cleared ILS means:
follow last vector and altitude assigned until establishing. Who descends from by their own choosing in the london tma??? Suicidal?!? |
Sounds like a knee-jerk response to a couple of ancient history cockups. Is the UK the only place this cumbersome phrase is used?
Mind you on PRMs we use something similar for the high-side ILS which has never been explained to my satisfaction (why would a pilot ever descend below GP below & before the IAF altitude? But if they were then we would lose separation.). |
In other areas of europe the FAF crossing height is around 3000 AGL and descending below that before capturing the GS is simply illegal. However an often used clearance is "leave Axxxxft when established on the G/S".
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Err......
As one who is often "buggering about" underneath LHR approach at 50ft below my ceiling (which changes along the heliroutes) I personally don't mind how many "separate" clearances it takes to keep big tin out of my rotor. So long as there is no confusion, it'll all be fine. |
John R81..... Wise words. Thank God someone on here understands!!
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