View Full Version : "Cleared ILS Approach..."
12th Oct 2001, 23:57
There. That wasn't so hard was it. That's all you have to say once you've vectored Flt XYZ on to the final cut for the localiser. Guaranteed he/she will intercept the localiser and then descend on the glidepath.
So why, in the UK, do controllers insist on delaying the descent on glidepath until the a/c has called localiser established?
Whatever the reason, the following list is the consequences of about every fifth or so approach I make in the UK:
1. Due to r/t congestion, the LLZ Established call is not made until the aircraft is on glidepath in level flight, or already above the GP.
2. Once cleared to descend, if flying by auto (as per company sops) the approach is armed and a further 3 seconds elapse before the a/c is ready to capture the GP, which by now is well below the aircraft.
3. What follows is a scramble to go down and slow down, which is clearly identifiable to me as a link in the accident chain. Preoccupied by capturing the glidepath and slowing down so as to avoid a go around, the crew have reduced cockpit awareness and general SA. I've seen perfectly serene approaches under the finest of conditions completely bolloxed up by the above method!
Accidents happen under such duress.
It need not be like this.
"Cleared ILS Approach..."
:D :D :D
13th Oct 2001, 07:54
Been like that since time immemorial in the UK. Australia was the same until recently when we moved to ICAO standard phraseology. Must be very confusing for pilots, I wonder how many get fizzed for commencing descent in the UK when they should not have done. It's not as if there is someone underneath them...!
13th Oct 2001, 15:30
Hi Mr Approach,
Quote, "It's not as if there is someone underneath them...!" Incorrect!! In the London Control Zone there are all manner of helicopter routes, traffic spotters, police helicopters, air ambulances and zone transits operating beneath the ILS. This is precisely the reason why we don't clear aircraft for an ILS approach, as this techically allows the aircraft to descend immediately to its MDA. Unlikely you say? I've seen it happen.
13th Oct 2001, 15:31
There have been many discussions on this. Have a read.
PS MrApproach, there can sometimes be someone BELOW you, especially in the London area ;)
17th Oct 2001, 00:52
OK, so if there is someone over the Thames at 500' for instance, what would be wrong with;
"Not below 1500' until established on the glidepath, cleared ILS approach."
What is certain is that in trying to be extra safe in separating the low level traffic (btw, who has priority?), the controller can inadvertantly create an unsafe situation for the pilots, as outlined in my original post.
But if this is indeed such an old and boring topic for you guys, then I'll crawl back into my hole. I was just trying to make things safer.
Take care out there
17th Oct 2001, 17:37
Liverlittle. Heathrow Director on 120.4, which I've been doing the job for almost 30 years, is probably the busiest UK final approach frequency. In all those years I have only rarely experienced R/T congestion preventing someone from making a request for descent. (However, I've had lots of guys ask for descent to 3000 ft over London when we can't do it due to EGLC).
Of course we would very much like to provide the ideal descent profile so you hit the ILS at the precise point but for a number of reasons it is not always possible - late descent due to other traffic, for example. We do our best, but sometimes guys end up above the GP. That's the cost of an extremely busy commercial operation.
I don't see any problems with our current technique and see no reason to change it.
18th Oct 2001, 00:29
Heathrow Director. I note your comments. It's really only in the last 15 years or so that this will have become relevant. ie. more use of automation. Your comments seem to invalidate mine. Would you really be aware every time a descent was delayed due to congestion? We're not talking big deviations here. Just a few feet outside the capture range.
Perhaps I should ask in your 30 years of controlling how often have you seen aircraft intercepting the glidepath from above? That alone is poor technique and discouraged due to the presence of false glidepaths and the old chestnut of inadvertantly descending through the glidepath.
I understand that London airspace is busy and intercepts from above a necessary evil (did one today in fact, saved a minute or two. Thanks). But I'm raising the broader issue of standard procedure. The same problem occurs at quiet regional airports! It need not.
I still believe there is a safer alternative to the current procedure, as outlined above.
18th Oct 2001, 02:09
How about "Descend to altitude 3,500 ft (or whatever), descend further on the glidepath".
Always worked for me.
Of course it is incumbent on the controller to ensure the localiser is intercepted before GP capture.
18th Oct 2001, 02:44
Phraseology already exists in the UK which should alleviate the problems you describe.
Since December 2000 we've been allowed to say "when established on the localiser, descend on the ILS".
If used appropriately it should prevent the problems you describe in your initial post.
19th Oct 2001, 11:02
Copy that. Not used very often I'm afraid. Spread the word. Thanks.
19th Oct 2001, 12:56
Incidently does: "Decent altitude 2000ft further with the ILS." mean that I am cleared for the ILS???? I have heard this MANY times particularly at MAN. Usually we then get a "Descend with the ILS." However sometimes we dont! :confused: