ATC Descent planning

[NigelOnDraft]

Would appreciate any ATCOs thoughts on this :)
Twice recently I have been given almost unachievable descent requirements by ATC. On the LAM STAR, and we have "planned" for the standard FL250 at LOGAN, and FL150 at SABER. However, in each case, have been given an intermediate level off e.g. 5000' above. Let's say FL200 approaching SABER.
At some 12NM to SABER "XXX descend FL150, be level prior SABER". Now my 3x table makes this not possible, and certainly not with the 50K Easterly winds we have had the last few weeks at these heights. "Use your speedbrake" you say. Well apart from the fuel wasted, I do not like abruptly lowering the nose and yanking large amounts of speedbrake with passengers still up and about (they will tend to be strapped in, weather permitting, only on leaving the hold i.e. LAM).
As a "defence mechanism" I have taken to slowing right up while being held high i.e. on levelling at FL200, and knowing this is going to happen, slow to ~220K which then makes the FL150 more easily achievable. However, the increasing number of "minimum speed 290k (or even 300K :hmm: )" instructions make this difficult - one of your requests has to be "ignored" or disobeyed :ouch:
The general level of ATC transmissions are also so heavy that no requests can be made to "slow up" or "we can't make that". The other pilot might have read back the clearance without initially comprehending the inability to comply, and then cannot get a word in until after the restriction has been busted.
What "guidelines" do ATCOs work to over descent distances required? Do they take into account the wind e.g. tailwind? And do they take into account that having instructed us to maintain a high speed, they have removed the only flexibility we have left to try and "plan" for the STAR "plan to be FLxxx at XXX"?
Certain ATCOs are very "energy" aware, try and let us slow up if they know there's any holding (saves LOTS of fuel), and understand the KE v PE. Others unfortunately do not, and seem to think we just dial in a FL and/or speed, and hey presto, it happens :(

TIA....

[eyeinthesky]

I thnk your problem arose from the common area of a variety of awarenesses, not to say competencies, in some units. Any ATCO worth the name should know that, if you are given a 'when ready, to expect' clearance, then they cannot expect you to make that if they then level you off at an intermediate level. To help them, you should certainly pipe up and let them know it's impossible, as it will add to their learning!

QUOTE
What "guidelines" do ATCOs work to over descent distances required? Do they take into account the wind e.g. tailwind?
UNQUOTE

Many of us know the usual TOD points for a given cruise level to make a restriction, and will give descent instructions to allow this to happen. Sometimes we can get distracted or involved in other tasks, and may leave it late. If that's the case, we much appreciate your help in complying, unless the Stuka dive will upset the pax! But if it's impossible, say so and we will take the necessary action.
I must also confess that the strong easterlies at altitude recently have caught me out occasionally and I was happy to try to coordinate a different profile with the next sector when told that the restriction was unachievable. I'm afraid some people do it by numbers, however...

As a counter comment, can I outline the pointlessness of saying 'Request Descent', receiving a clearance and then just sitting there for another 15nm or, worse, saying "Is that when ready?". I know you want to set the level in the MCP and allow the aircraft to follow the VNAV path, but we have probably amended our plan to allow you to descend when you asked for it, and if you do not, you mess up the plan. So in the same way as some ATCOs do it by numbers, some pilots behave as computer operators and not pilots.

If you ask for descent, descend as soon as you receive the clearance!!

[NigelOnDraft]

eyeinthesky
Thanks for all that.
I know you want to set the level in the MCP and allow the aircraft to follow the VNAV pathNot me :uhoh: Never understand how that VNAV thing works in my Airbus... and/or spend more time trying to work out what it's trying to do! 3x table with wind / speed corrections do fine :D
If you ask for descent, descend as soon as you receive the clearance!!Always would do, and can understand your concern when some don't :{
Thanks again - all the issues that would / should be sorted by visits / famil flights!
NoD

[MancBoy]

Totally agree, if you want to come and plug in with me on CLN sector when its baklls out with inbounds you're more than welcome.


The strong NE of the last few weeks causes no end of problems streaming traffic for ABBOT and LAM, as a suggestion rather than entering UK airspace at FL340 and above why not ask Maastricht for an earlier descent if you know you've got to make a restriction by LOGAN or IDESI?

This would also encourage our colleagues at Maastricht to initiate the streaming for us which would help things run a bit smoother

[NigelOnDraft]

Mancboy...
as a suggestion rather than entering UK airspace at FL340 and above why not ask Maastricht for an earlier descent if you know you've got to make a restriction by LOGAN Seem to be at cross purposes :confused:
We've no problem with calculating or obtaining the initial descent. It's being only descended to 5000' above the restriction, then held there until we cannot make it, and then being told "Descend FLxxx by XXXX" :ooh: The trouble is we don't know if you are going to require it... with holding sometimes we are held well above it, so the FL200 level off may seem OK.. until the aformentioned RT call :ouch:
And also with the RT traffic being so heavy you sometimes cannot check in for 2-3 mins, it is difficult to "ask" or "check" or "clarify"... but that's really out of your control as well :{

[Northerner]

Sounds to me like you are talking about TC East, the airspace between Logan and Lam. A part of the problem here is that unfortunately there are usually quite a few of you pilot chappies about, and the poor guy/gal working on east has to try and give you what is already a tight descent clearance, in airspace which is narrowing, and stream you for Lam in the hope that you won't hold, hence the speed restrictions, not to mention working you around the other inbounds and the overflights. The speed may also be for separation from the one in front and the one behind too!

I'm not suggesting that we couldn't do to learn more about whether what we are asking you is possible or not - of course we all could. Just that they may be doing a particularly tricky task and trying to give lots of planes a good service. In general you all arrive at once, hence the R/T is bad too... we understand. Just keep trying to get your work in edgewise and let them know what they are asking is just not achieveable.

Someone who does the sector may be able to help more (I used to, but don't any more.)

Cheers,
N

:ok:

"Keep smiling, it makes people wonder what you're up to...."

[055166k]

Nigel, your post describes several deficiencies in the ATC service provided; from lack of awareness and poor training to kamikaze flow control.....but of most relevance....the demise of what was once a healthy familiarisation flight scheme.
I urge you and fellow pilots to add comments to your voyage report.....if your chief pilot considers the accumulated reports to be significant...forward them to the CAA. You are customers and you really must lodge a complaint or comment to ATC whenever the service provision has been less than ideal...and I suggest that anything over 70% R/T loading is a justifiable safety concern [studies done in 80's].
Help us to help you, and remember that not all controllers have an interest in aviation, some just do it for the money.

[SMOC]

As a counter comment, can I outline the pointlessness of saying 'Request Descent', receiving a clearance and then just sitting there for another 15nm or, worse, saying "Is that when ready?". I know you want to set the level in the MCP and allow the aircraft to follow the VNAV path, but we have probably amended our plan to allow you to descend when you asked for it, and if you do not, you mess up the plan. So in the same way as some ATCOs do it by numbers, some pilots behave as computer operators and not pilots.
If you ask for descent, descend as soon as you receive the clearance!!
The problem arises when you can't get a word in when you want to descend, so put one in early when you hear a gap.
Would you prefer "request descent when ready" or "request descent in 2 min or 15 miles"? I'd say if there's a lot of ATC chat going on most guys would be calling early and would like to hear "when ready" in the reply, otherwise the two in the cockpit start saying to each other "is that now or when ready, better ask and find out" :rolleyes:.

You're right about being computers, or creatures of habit, not in glass so my descent point is to the mile and going down early means I have to think a little :{ to regain the profile, which brings me to the point of, do you take into your plan that we will probably being going down at 500FPM until we intercept our original descent profile? That way I can set idle thrust and lock onto a speed and just monitor or for glass get onto the VNAV profile and monitor.

Off topic, can you visit ATC or is that all over since 911?

Regards

[PPRuNe Radar]

Visits to ATC units are not usually a problem to arrange for bona fide visitors from the industry. A previous issue of CHIRP had a list of contacts, but you can also glean numbers from the AIP or Jeppesens, etc.

Other folks can also be accomodated if you have someone on the inside who makes the arrangements and shows them around.

[Scott Voigt]

I'm probably going to get a bit flamed for this, but when you are up to your ears in airplanes and trying to get keep everything moving and apart, you really don't care about fuel, you are just trying to keep it all together and moving with the least amount of delay...

regards

Scott

[NigelOnDraft]

Scott...

I wouldn't flame you ;) of course. Just trying to say the airline, and hence myself, are obviously doing all we can to reduce fuel consumption. So for instance, the suggestion above to try and "beat" the ATC system and get an early descent from the previous sector just won't happen.

[250 kts]

If I know I'm going to have to put a speed on early then I always give an indication of what I'll need. eg. Plan on a 280kt descent or whatever I decide . At least then you have some idea to plan your profile.
If there's holding at LAM I can't really undertsand why they would still need the 150 at SABER as that is there to ensure you make Min Stack at LAM and 250 kts. If there's holding you wouldn't need to achieve Min Stack.

[Slippers]

250,

The FL150 level Saber restriction is not only there to ensure the inbounds make min stack by LAM, it is also there to assist in providing separation against the Gatwick departure climbing out towards CLN. These are climbed to FL170 by TC North and pointed 5-10 miles west of Saber. If the inbounds are floating down over Saber at FL180 or above, this makes this cross over much more tricky.

[REVOLUTION]

I think part of the problem stems from aircraft being slowed to 270/280kts miles out for the purposes of streaming. We've had 'discussions' about this before and CLN sector (based at Swanwick) are obsessed with trying to put everything in trail, TC East and Lambourne (based at West Drayton) do not want aircraft in trail, particularly when there are lots of inbounds. If aircraft where not streamed and restricted to slow speeds they would make the standing agreement levels. Pilots must find it a bit odd when they are transferred to TC East and are told 'no speed restriction fly heading....' after they've been slowed to 27okts for the last 30 miles but the above is the reason why.

Everyone knows aircraft 'can't slow down and go down'.

Having said that though for an ATCO to say descend FL150 be level by Saber when an aircraft is clearly not going to make it is poor, and I've heard it said.

The priority in the London TMA is for aircraft to make their standing agreement levels, then they can slow down.

[MancBoy]

Revolution, CLN doesnt just deal with TMA inbounds now does it?

Traffic has to be streamed in order to make room for all the european outbounds that we get. Remember 5 miles makes a lot of a difference compared to three miles and because of the tunnel effect of sectors 13 and 14 you can rapidly run out of space if you've got more than 4 aircraft abreast.

I agree that too many people use speed control when it is unnecessary but when you've got 747s and 777s etc hoovering f100s, 737s what else are we supposed to do? If we just give you traffic in the hope that you descend it so we can descend other traffic then things will rapidly come unstuck.

When TC join us at Swanwick as one of the training officers on our watch i'm gonna really push for TC bods and AC bods to sit in on each others sectors more and to even have a go. I remember when one of my old friends in TC came down for a look see on CLN as he did TC east and his eyes were opened to just how little space we've got to achieve what we have to.

If you dont want everything in trail then get your ops dept to set it in stone i n the part 2 and then everyone will know what TC want, as we are there to serve you obviously!

[250 kts]

250,
The FL150 level Saber restriction is not only there to ensure the inbounds make min stack by LAM, it is also there to assist in providing separation against the Gatwick departure climbing out towards CLN. These are climbed to FL170 by TC North and pointed 5-10 miles west of Saber. If the inbounds are floating down over Saber at FL180 or above, this makes this cross over much more tricky.
Thanks for that slippers. I don't actually do the sector but assumed the restriction was just for descent purposes.

REVOLUTION.

If you really want them upto 4 abreast just say-not a problem! I will usually only use the 270/280kts if I know there is holding and at that speed they will all make the appropriate level as long as they're pre-warned. I can't believe you would take off that sort of speed if you're holding anyway.
I do agree that one or two of the watches are completely obsessed with streaming but it ain't all of us by any means.