A question for ATC
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A question for ATC
I have a question for you ATC guys and gals.
On the whole you do an excellent job. But just recently I have noticed that I have been doing a lot of intercepting the glideslope from above.
Is this now a formal policy of yours, because, although we can make it in on that sort of approach, it is far from ideal and does make the old ticker start beating a tad faster?
On the whole you do an excellent job. But just recently I have noticed that I have been doing a lot of intercepting the glideslope from above.
Is this now a formal policy of yours, because, although we can make it in on that sort of approach, it is far from ideal and does make the old ticker start beating a tad faster?
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Hi A.B.M.
As an ex EGLL Approach Controller, I would say that the Continuous Descent Approach procedure sometimes meant that aircraft intercepted the glidepath from above. However ranges were always given to allow pilots to calculate a suitable rate of descent from FL70 (or thereabouts) right down to touchdown in order to avoid levelling off, and the resultant application of power and therefore noise. There is no policy within NATS that I know of which would lead to aircraft being routinely vectored to intercept the glidepath from above. I suggest you ask for a range check if this is not given with the descent clearance and adjust your ROD accordingly.
As an ex EGLL Approach Controller, I would say that the Continuous Descent Approach procedure sometimes meant that aircraft intercepted the glidepath from above. However ranges were always given to allow pilots to calculate a suitable rate of descent from FL70 (or thereabouts) right down to touchdown in order to avoid levelling off, and the resultant application of power and therefore noise. There is no policy within NATS that I know of which would lead to aircraft being routinely vectored to intercept the glidepath from above. I suggest you ask for a range check if this is not given with the descent clearance and adjust your ROD accordingly.
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ATCO Two,
I have to agree with Autobrake etc, it is not a matter of calculating a constant descent path, it is more that the cleared alt (around 3,000ft) is frequently right on or sometimes just above GS intercept point.
Our ac gives a rather uncomfortable ride if we arm GS when it is right on the money as the capture is very positive. It can also be the devils own job to hit the GS from above while coming back to 160 without early gear selection which we would rather delay for the reason of noise that you mention.
All we need is a little more room because sometimes all it takes is the delay caused for someone else to come onto the freq to screw the intercept.
[This message has been edited by Old Pilot (edited 12 April 1999).]
I have to agree with Autobrake etc, it is not a matter of calculating a constant descent path, it is more that the cleared alt (around 3,000ft) is frequently right on or sometimes just above GS intercept point.
Our ac gives a rather uncomfortable ride if we arm GS when it is right on the money as the capture is very positive. It can also be the devils own job to hit the GS from above while coming back to 160 without early gear selection which we would rather delay for the reason of noise that you mention.
All we need is a little more room because sometimes all it takes is the delay caused for someone else to come onto the freq to screw the intercept.
[This message has been edited by Old Pilot (edited 12 April 1999).]
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Hi Old Pilot,
Another constraint on 27L/27R at EGLL is the interreaction with London City SIDs which climb to 3000 ft under the Heathrow inbounds descending to 4000 ft. This means that Heathrow traffic may not be descended to 3000 ft until within 13 nm of the airport. I would add that if the Director sees from mode C that you are well above the glidepath he/she should offer further descent to 2500 ft or 2000 ft as appropriate. (This usually involves co-ordination with the Heathrow SVFR Controller to avoid possible conflictions with low level traffic in the London Control Zone - 1000 ft vertical or 3 nm horizontal separation required). It's a question of balancing the needs of the various airspace users in the London area, I'm afraid.
Another constraint on 27L/27R at EGLL is the interreaction with London City SIDs which climb to 3000 ft under the Heathrow inbounds descending to 4000 ft. This means that Heathrow traffic may not be descended to 3000 ft until within 13 nm of the airport. I would add that if the Director sees from mode C that you are well above the glidepath he/she should offer further descent to 2500 ft or 2000 ft as appropriate. (This usually involves co-ordination with the Heathrow SVFR Controller to avoid possible conflictions with low level traffic in the London Control Zone - 1000 ft vertical or 3 nm horizontal separation required). It's a question of balancing the needs of the various airspace users in the London area, I'm afraid.
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You might be just the chap to help with another discussion point. Whilst we sat there today shuffling down the stack, we wondered what the dimensions of a level were. When asked 'descend level X, call leaving Y', how far out of X do we have to be to be leaving it? I'm pretty sure the answer is 200' but I can't remember where that came from. What's the definitive answer?
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Hi Capt Peacock,
There are two issues here. Firstly when you report leaving a level a Controller can then immediately procedurally allocate that level to the next aircraft. Probably best to wait a few seconds though, I'd say!
Secondly, the use of mode C to assess level occupancy. An aircraft is not considered to have left a level until its mode C readout indicates 400' from that level in the anticipated direction. Same goes for passing through a level. An aircraft is considered to be maintaining a level if its mode C readout indicates +/- 200' from that level. Hope this helps.
There are two issues here. Firstly when you report leaving a level a Controller can then immediately procedurally allocate that level to the next aircraft. Probably best to wait a few seconds though, I'd say!
Secondly, the use of mode C to assess level occupancy. An aircraft is not considered to have left a level until its mode C readout indicates 400' from that level in the anticipated direction. Same goes for passing through a level. An aircraft is considered to be maintaining a level if its mode C readout indicates +/- 200' from that level. Hope this helps.
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I hear you L&C Autobrake. While I sympathise with my collegues from Heathrow not being afforded the luxury of AIRSPACE, the policy in Dubai has always been one of a standard ICAO intercept ie to permit a period of level flight (usually around two to three miles) on the LLZ before intercepting the G/P. We generally strive to achieve this but its not always possible - particularly if the sequence is tight and we are trying to make a slot for you. If that`s the case I would generally ask if a short approach is acceptable and give tracks to touchdown. You might even get a visual!!
