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When level reduce to holding speed

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When level reduce to holding speed

Old 4th Feb 2011, 16:40
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When level reduce to holding speed

This instruction has been common for quite a few years but before that we were simply given be level by saber/tiger etc and we could reduce speed at our discretion if holding. If I make the restriction at saber/tiger and there is holding why can't I reduce speed in the descent? Why do I have to wait until level? My guess is I am not trusted to make the level restriction and reduce speed or can't be trusted to maintain a sensible rate of descent. What is the real answer?
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Old 4th Feb 2011, 17:09
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Hi hotmetal.

'Not trusted' is a harsh way of putting it.... (But probably true ) there could be many many many reasons why you are being given this.

a) For years I have had drummed into me that aircraft can't go down and slow down. Therefore if I need the height restriction then I will say this as the level is more important.

The level by restriction could be for many reasons... it might be there to separate you from another aeroplane, or someone else's airspace, in which case I need to be sure you will make that level.

b) Maybe I need you to not slow down initially so you keep your place in the queue?

c) Maybe I've got another aircraft coming behind you who is not yet level separated but will be once I've got you level, and if you slow up that could erode my separation.

These are just a couple that spring readily to mind...

If I can let you slow up early I will, and regularly do. We just have to try to balance everything for every flight that we work, and sometimes that means you don't get exactly what you want. (don't mean that to sound harsh...)

Keep asking questions and see if you can come to visit us sometime... we all need to learn so much more about each others profession. (I readily admit that I should know more about your job than I do...)


Cheers,
Northerner

"Keep smiling, it makes people wonder what you're up to... ;)"
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Old 4th Feb 2011, 17:11
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Personally I don't like this instruction, as what happens if the next sector gives further descent and you don't actually "level". I always use "make the level restriction by xxx and when able reduce speed" however there are the "chosen few" who have to not understand this one. If you are not actually issued a speed or speed band, then you can fly whatever speed you wish (until you level), the controller should use more control if they don't want you to slow down too early. The level restrictions in that area and many others are important for a variety of reasons so getting you down is our number one priority, you slowing down is further down the list in most cases.
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Old 4th Feb 2011, 17:16
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Unless you are on a speed control instruction then, providing you can make the 'level by .....' restriction, you can fly as slow or as quick as you like. I think that the "when level reduce to holding speed" instruction is a habit which has come about by pilots requesting to slow down and controllers trying to be helpfull in reducing the time spent at the holding fix, when infact the speed decision is completely in the hands of the pilot and does not need to be mentioned to the controller.
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Old 4th Feb 2011, 18:29
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I suspect it is a habit that has crept in too. The 'can't go down and slow down' thing is obviously true to a certain extent but what I would like to do if I know I will be holding is to use a vertical speed to arrange my descent to be exactly 150 by TIGER, say, wind the speed back and accept a slow decelleration to my selected speed. If ATC need a particular speed for spacing then fair enough. I just suspect there is a bit of over controlling happening. Just tell me what you require and I'll do it. If you don't really require something then leave it to me.
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Old 4th Feb 2011, 19:35
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hotmetal, unfortunately there are always the breed that don't do the ideal and somehow manage to abuse even the simplest of instructions so by overcontrolling, we know we are certain to get the desired levels with the minimum of fuss. Just this morning I got a correct readback for making FL150 by TIGER and the next transmission from me was "make the level restriction and reduce speed when able, 20 minute delay" to get the response "disregard the level restriction and pulling the speed back". English speaking LHR based shorthaul a/c. Fortunately it wasn't too busy so the added RTF didn't impact on my tasks.
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Old 4th Feb 2011, 21:36
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Depending how it is used it is a perfecty acceptable, and indeed sensible instruction. Using the FL150 by TIGER restriction... quite (very) often there will be aircraft in trail all descending to FL150, all on speed restrictions to maintain separation.

There is 10-15 mins holding for EGLL. You are transferred to TC who need separation by the time you hit the hold.
You are number 1 of 3 in trail.
You call on "ABC123 descending FL150 level TIGER maintaining 300Kts".
Controller replies "ABC123 Descend FL130, when level reduce to holding speed, delay 10-15 minutes".

This instruction ensures you maintain the speed control set up by previous sector, and lets you slow down as soon as you have reached a level that leaves space for the following aircraft.


If the levels are available at the hold, it could just as easily be "descend FL100, reduce to holding speed on passing FL130, delay 10-15 mins"
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Old 4th Feb 2011, 22:37
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anotherthing,
all very interesting, but academic, and, (allegedly), shortly to be historic.
According to literature in my possession, (and printed on very posh expensive paper to-boot), a NATS 'CO2 GURU' wants to eliminate holding completely.
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Old 5th Feb 2011, 08:59
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anotherthing,
all very interesting, but academic, and, (allegedly), shortly to be historic.
According to literature in my possession, (and printed on very posh expensive paper to-boot), a NATS 'CO2 GURU' wants to eliminate holding completely.
Easy, reduce the declared capacity to around 25 to 30 an hour.

Sorted!
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Old 5th Feb 2011, 11:07
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unfortunately there are always the breed that don't do the ideal and somehow manage to abuse even the simplest of instructions so by overcontrolling, we know we are certain to get the desired levels with the minimum of fuss. Just this morning I got a correct readback for making FL150 by TIGER and the next transmission from me was "make the level restriction and reduce speed when able, 20 minute delay" to get the response "disregard the level restriction and pulling the speed back". English speaking LHR based shorthaul a/c. Fortunately it wasn't too busy so the added RTF didn't impact on my tasks.
Doesn't that support my argument? You can say what you want and people will still occasionally make errors. Just constantly saying an unnecessary instruction may give an illusion of security but errors will still happen. Its a bit like telling passengers to please take all their personal belongings with them. It won't stop people forgetting stuff. So just tell me the level restriction and I will make it [unless I make an error] and only give me a speed if it is required for spacing or whatever.
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Old 5th Feb 2011, 14:05
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Surely if you're given a speed it IS for spacing, to either maintain or increase the distance between you and the one in front and or behind, if not then the controller is obviously a bit of a .......
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Old 5th Feb 2011, 14:08
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You are right that everyone should be working to the same standards and understanding, but that is not the case.

Only recently I was working a stream of inbounds to the LTMA from the east. I had told every aircraft joining the frequency that the delay was approx 10 mins and suggested a suitable conversion speed which kept the stream apart but also didn't push them into the LTMA at 300kts or more (not sure I agree with anotherthing's scenario of 300kts into the hold for this reason!)

One aircrew from a certain major UK carrier based at Heathrow reported the actual indicated airspeed as 270kts. Since he was at the head of that bunch of traffic but some miles behind the previous bunch, I requested him to fly not less than 270kts. Imagine my surprise to see him accelerate and threaten to catch up the bunch in front. When questioned, he reported his indicated as 325kts! This into a 10 minute hold that he had been told about and was an increase of 55kts from the speed he had previously been flying!

Unfortunately we have to deal with the lowest common denominator, and some of the reasons already given may help to explain why a speed reduction may not be a good idea in the descent.

However, as with all things ATC, if you need clarification at the time: ask!
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Old 5th Feb 2011, 16:45
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hotmetal, as eyeinthesky says, there are the few who with the delay information still go full pelt. I have no idea who the few are going to be, so everyone gets the same instructions to slow down asap. Overcontrolling from your part is safely and orderly in my world, numbers one and two on my list of goals.

Not Long Now, not always. Sometimes it is just as easy to say "when able 250kts" just to keep them away from the stacks a bit longer, no longitudinal separation reasons at all. Use this when very busy.
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Old 5th Feb 2011, 18:55
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So if very busy why not 220 or min clean?
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Old 5th Feb 2011, 21:15
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Very unlikely to get them down to the SA's at min clean, even 250kts is usually a push. All depends on winds and if the French remember to give us the traffic, and all not on top of each other....
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Old 6th Feb 2011, 18:40
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I requested him to fly not less than 270kts. Imagine my surprise to see him accelerate and threaten to catch up the bunch in front. When questioned, he reported his indicated as 325kts! This into a 10 minute hold that he had been told about and was an increase of 55kts from the speed he had previously been flying!
I fully agree it's not good airmanship but he actually didn't do anything wrong. I would suggest it would have been better to leave the speed at 270kts or even 250kts and allow the gap to be maintained and maybe allow some of the airborne holding to reduce.
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Old 6th Feb 2011, 21:39
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A lot of the comments point to the modern ATC curse of Chronic Overcontrol.....I see it everyday. The pilot told min 270 knots might justifiably think he/she was helping the overall situation by speeding up......pilots are not psychic...if you need a speed.....give a speed. As for "min clean" forget it....250 knots outside the TMA works for me. Perhaps pilot buddies can help.....I was told by one pilot that prolonged flight at "min clean" can use up a lot of gas....and "min clean" imposed a long way out may require "the brakes" to make the level.....losing energy and efficiency and wasting more gas.
Modern ATC looks like a super-dooper video game......never has there been a greater need for Fam flights and operational controller/pilot liaison.
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Old 6th Feb 2011, 21:46
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055166K

Agree entirely. Never needed or even considered the phrase min clean speed. Whatever happened to parallel headings?

250kts works for me too-oh that's me.
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Old 6th Feb 2011, 21:49
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Ah, "operational controller/pilot liason". Remember it well.
A great shame that the 'centres' are now many tens of miles from the places where pilots operate from.
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Old 7th Feb 2011, 08:07
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We have very few pilots visit the Tower where I work, despite it being attached to the terminals, so location is not necessarily the issue! I don't think it's something that a lot of pilots are interested in doing for some reason.
The few that have made the visit and stayed for an hour or so to plug in, say they have found it worthwhile, if only to appreciate why speed control is issued , or why they can't always be number 1!

louby
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