Go Back  PPRuNe Forums > Ground & Other Ops Forums > ATC Issues
Reload this Page >

270KT outer speed limit for london TMA

ATC Issues A place where pilots may enter the 'lions den' that is Air Traffic Control in complete safety and find out the answers to all those obscure topics which you always wanted to know the answer to but were afraid to ask.

270KT outer speed limit for london TMA

Old 3rd Jun 2008, 12:48
  #61 (permalink)  
wizad
Guest
 
Posts: n/a
if they want to save money and the planet (in that order) get cracking with more environment friendly aircraft.
the billions airbus and boeing must rake in, car companies are getting onto it so im sure it must be top of the agenda.
rather than looking outward at what an overstretched ATC can do in very confined, busy and complex airspace, that given time im sure will attribute to a safety error of some sort, how about looking inward at the people they are buying these aircraft from and demanding a greener solution.
Seemingly now every month we turn up to work to find our procedures changed via the EBS, jesus.... the national curriculum gets changed less than that.

W
 
Old 4th Jun 2008, 12:03
  #62 (permalink)  
 
Join Date: Apr 2008
Location: At home
Posts: 2
A/C today calling well over France 25 miles before RFD/RDT requesting descent.
If this trial is to be done then the French sectors at Brest and Reims need to get these a/c down earlier.
Do the office bods want us to call the French when we receive an estimate and tell them it cannot be accepted. Maybe the Watch sup should do it at the start of a shift, even better NOTAM the restriction for the remainder of the trial and cap all KK + LL inbounds to max level 280. See how that goes.
yoCu is offline  
Old 5th Jun 2008, 13:41
  #63 (permalink)  
 
Join Date: Dec 2000
Location: Samsonite Avenue
Posts: 1,520
This is an extract from NATS....

Modelling and simulations have indicated that approximately 1 minute of airborne holding can be avoided with an earlier and consistent application of econ descent speeds. By reducing the speed earlier, this procedure simply transfers part of the anticipated stack holding delay to the descent phase, thus reducing fuel burn and aviation related emissions. Total potential savings for LTMA arrivals are expected to exceed 12,000 tonnes of fuel per annum.
Mister Geezer is offline  
Old 5th Jun 2008, 15:08
  #64 (permalink)  
 
Join Date: Feb 2006
Location: southampton
Posts: 225
Reducing emissions is all very well and good but i can't see how it'll save holding time. Instead of all the inbounds arriving at the holds at 300kts at the same time they will all arrive at the same time at 270kts. If they are all arriving at the same time how does it reduce holding?

At the end of the day it's all about reducing fuel costs and burn, nowt to do with CO2 emissions, the fact that they may reduce is a bonus that the airlines and NATS will be able to trumpet later on when they announce their save the planet scheme.

If certain airlines want their pilots to fly more economically then thats fine i will accomodate them aslong as they let me know. But i'm an ATCO not a pilot, its not for me to impose a descent speed on an aircraft when its not for streaming purposes. I'll leave the flying to the guys in the cockpit thanks. I'll stop them from getting too close and to do that i need all the tools that i can get, having a imposed speed restriction (cos thats what it will turn into) reduces the amount of flexibility that i have.
1985 is offline  
Old 7th Jul 2008, 07:48
  #65 (permalink)  
 
Join Date: Dec 2003
Location: UK
Posts: 214
I've been subjected to this 270kts trial a few times now and frankly I wish it would be withdrawn immediately. Some observations:

1. The trial is costing fuel. When we were allowed to use our own speeds, if I was going high on the profile I'd add accelerate a bit and conversely if I was starting to get a bit low I would reduce speed thereby altering the glide angle. This would be done with the thrust levers remaining at idle.

Under the new regime the only options available to me are to use speedbrake if I am high or thrust if I am low. During some descents I am now having to use speedbrake to meet (say) the TIGER restriction yet I am also having to apply power to fly level at FL120 at 270kts. Previously I would have dived off the excess height and reduced speed below FL150 to either prevent levelling off at FL120 or to level off, thrust at idle and start slowing down for the hold.

2. Because of the trial I am more likely to be further from the ideal profile than before the trial. At 270kts we need to be starting down before we enter London airspace. Typically we ask the French for descent, they (quite rightly) QSY us to London and by the time we check in we are above the profile. Because we are restricted to 270kts diving the height off is not possible so out comes the speedbrake.

In recent years the boffins at NATS/SRG have come up with some schemes which probably seem reasonable and sensible in a meeting room, but which operationally aren't so smart and risk introducing a lack of respect for the UK ATC system (eg. current taxiway position included in line up clearance, new ATSOCAS, 270kt trial, full spiel given to GMP when details passed during DCL request etc.). The 270kts trial falls in to this category because it quite plainly does not achieve its stated aim yet we persist with it. Because we can end up above the profile the risk exists that people will carry on towards TIGER, for instance, knowing that they will not meet the restriction but confident that the next controller will issue a lower level thereby cancelling the previous restriction. Alternatively people will use the expression "on transition" to their own advantage and choose to "transition" at FL150!

3. The 270kts seems to be increasing the workload for some ATCOs. I have had the restriction applied and then the controller has used vertical separation against the preceeding traffic. If I am close enough to the preceeding traffic that vertical separation is required instead of just speed control, it stands to reason that if they are on the correct profile, I must be above it. Furthermore because we must fly AT 270kts, we can no longer give you guys bursts of high ROD (to do that we used to dial the speed up and pull the speedbrake out). So waiting until we are almost on top of a level restriction before issuing it will now lead to non-compliance.

4. The trial seems to remove the ability for ATCOs to take maximum tactical advantage from a given traffic situation. Coming off the Atlantic recently with the 270kts in place we were given to TC OCK who not only lifted the restriction but asked us for high speed to help with the flow in to LL. We gratefully gave them and INT S 330kts. I don't mind doing that, but I could have arrived at the same point and time in space if I'd been allowed to fly my normal speeds. Not only that, I could have done it at idle thrust the whole way.

Conclusion: This trial is costing me fuel, time and grey hairs.

G W-H
Giles Wembley-Hogg is offline  
Old 7th Jul 2008, 10:06
  #66 (permalink)  
 
Join Date: Nov 2000
Location: Dre's mum's house
Posts: 1,432
Time to revise the route structure?

as one who is forced by the present route structure which hasn't changed in years - not since OTR etc vanished in 02 - maybe it would be beneficial to revamp the route structure and enlarge the London TMA.

When I depart EMA in my 737NG I invariably have to fly through London to go anywhere south or east: I have to explain to the newbies why we always get a radar heading t the west and then vectors to BIG or DVR or SAM.

There doesn't exist a route that I can take from the North towards norwich and then out over Amsterdam to avoid London if I'm going to Poland or Germany.

If I'm going to Spain or the Canaries I can't take a diagonal SW towards Brecon to go around the TMA.

Similarly inbound i have to be at FL270 35 before LAM to be FL220 by HEMEL from the east when I could route further north and keep out of your way.

From Spain and the Canaries I have to route around the west of London - normally smack over the top of LHR to make 220 by HEMEL again.

It strikes me that working with old routes with modern high performance jet aircraft ( most of them don't like low speed descent as they simply don't go down!) with very accurute nav kit ( 2 x GPS, 2X IRs, DME DME upadting and 2 x FMC) is creating huge mounts of unnecessary work for you.

Is there a meachanism whereby you can, based on your knowledge of the inbound stream schedule, allocate a time and level at an inbound "gate" to each arriving aircraft?

The crew can then just plug that in to the FMC and let the airplane calculate it's cruise speed to make that "gate"; if it was done early enough, e.g. when BAW / VIR XXX calls for clearance to LHR at JFK and is given the gate time / FL as part of the clearance it makes the job easy as there is a lot of time to make adjustments.

Obviously slightly tricker for a shorter flight time e.g LBA to LHR or GLA to LHR but they can absorb the delay on the ground.

Something has to be done as the capacity of the airspace to absorb all the traffic is limited by the ATC capability.
The Real Slim Shady is offline  
Old 7th Jul 2008, 13:06
  #67 (permalink)  
 
Join Date: Mar 2006
Location: Swanwick
Age: 39
Posts: 43
Slim,
In some ways, I totally agree with you. As a TMA Controller, there is some limitations to what we can do as controllers. But there have been airspace developments, and there will continue to be...
To say that you cant go east without flying over london from EMA is not true, P155 goes east... via a point called SIVDA i think. This was a development a while back. Its true that if you want to go to DVR, you gotta go over london, but if you drew a straight line from EMA to DVR, I dont think you'd find it goes far away from LHR, and it would fly right over the top of stansted...

Your gate idea sounds grand... And very simple for you as pilots... Just type it into the FMC and bobs your fathers brother... But the route structure around London is a little more complicated than that. EMA is lucky, its right out of the way... But if you want to go south, its slap bang in the way. Outbound, you must climb through every TMA inbound, inbound, you've gotta go through every TMA outbound. At night, you are pretty much routed direct from the south coast for a 10 mile final at EMA, during the day its not that easy unfortunately. Not only for us, but for LMS, LUS and the host of other London sectors that try and get you and your 737NG from 380 to ground level.

And you're 737ng is a great performing aircraft, and we as controllers love their performance. But what about the 747s of this world? Great planes, but not great performance. Will they have to route a different direction just because you can outperform them? Should you get a more direct routing because you can do 4000ft a min? The route strucutre is there so every aircraft can make all the level restrictions across the board... (Oh and the LHR-GLA aircraft are gonna love delays on the ground, thats really gonna cheer them up lol)

Something is being done about the capacity issue... PRNAV... But thats a whole other topic for a whole other day...

Any more specific questions about why things happen, please PM me, I'll try and explain it best i can...
Medway Control is offline  
Old 7th Jul 2008, 13:41
  #68 (permalink)  
 
Join Date: Feb 2006
Location: southampton
Posts: 225
Slim, medway is right you can route via sivda and UP155 to either somva or redfa on the london/maas boundary that would take you way from london.

as for the FL270 35 B4 Lam restriction, its hard we are aware its restrictive and that you would like to stay higher but the idea is to get you below all the crusing traffic over london at FL300 plus, it would be an absolute bugger to get you down when you want. Routeing you further north is not really an option as you would crossing the tracks of and be descending into the teeth of all the departures from the TMA going east. And obviously we don't have the option leaving you high and descending later because of the military/uncontrolled airspace over East anglia, lincolnshire etc. The mil wouldn't want to know and we are too busy to provide you with a RIS/RAS and against the traffic out there. We are simply too busy with the stuff inside CAS to do that.

you should be able to route SW to BCN on weekends and in the evenings if you are happy with a service from the mil, EGBB departures do it so i can't think why EMA depts can't. I'm sure someone else will tell me if i'm wrong.
1985 is offline  
Old 7th Jul 2008, 19:51
  #69 (permalink)  
 
Join Date: Nov 2000
Location: Dre's mum's house
Posts: 1,432
Guys, sorry I probably didn't make myself clear enough.

We do route via SIVDA and I'm not complaining about the routings I'm given because I have a small understanding of the route structure inbound to the TMA from the north and how we, on our departures, tend to be in the way of arrivals and departures north.

Our arrivals from the east though often chuck us in to a sector, Clacton probably, when we are descending towards LAM, where the mate working the sector can hardly draw breath he / she is so busy. Any soltion to take non essential traffic away from these busy areas must be welcome.

I just feel that with the quality of navigation accuracy now, laterally and vertically, a massive restructure of European, not just UK airspace, which would offer benefits all round, is long overdue.

Any discussion / plan, however, should be done in close consultation with the workers at the coalface who have to implement the procedures.
The Real Slim Shady is offline  
Old 7th Jul 2008, 23:15
  #70 (permalink)  
 
Join Date: Dec 2004
Location: Down South
Posts: 294
This is an extract from NATS....

Quote:
Modelling and simulations have indicated that approximately 1 minute of airborne holding can be avoided with an earlier and consistent application of econ descent speeds. By reducing the speed earlier, this procedure simply transfers part of the anticipated stack holding delay to the descent phase, thus reducing fuel burn and aviation related emissions. Total potential savings for LTMA arrivals are expected to exceed 12,000 tonnes of fuel per annum.
What no one seems to have pointed out to the office jockey that thought this up is that if everyone arrives at the holding stack doing 270 kts and one minute later, then the problem still isn't going to go away.

Personally, I've not used it and won't unless I'm forced to. More often than not, traffic patterns won't allow me to do this - if the front aircraft I'm streaming is doing 270kts, then the back one will have to be doing 220 which isn't going to work. If there's no need for speed control, then I'll let the plane fly its own speed
The Many Tentacles is offline  
Old 8th Jul 2008, 10:43
  #71 (permalink)  
 
Join Date: May 2001
Location: London,England
Posts: 1,323
Personally I don't really care what speed we fly in the descent, the priority at $1300 a tonne is to make an efficient descent which now generally means slow not fast.

The really important thing is to know what speed is required BEFORE you start down, planning a 250kt descent and then having to fly at 300kts for spacing is hugely inefficient, you need to add power to stay on profile (bad) or fly level at the bottom (even worse). Conversely having planned a fast descent and being told to slow down means you have spent a few minutes more in the cruise (100+kgs even for a small Airbus) and have to speedbrake the height off to stay on profile. In an A320 the difference between an efficient descent and a bad one (power on to keep the speed up etc.) can be 200+kgs which is around $260 per descent at today's prices.

I would think we (bmi) do about 30,000 sectors a year into LHR so we are talking about huge sums of money that can potentially be wasted or saved and we really need ATC on side to help us out. If it's possible to tell us what speed you want before we start the descent it's a big help.
Max Angle is offline  
Old 8th Jul 2008, 15:28
  #72 (permalink)  
 
Join Date: Feb 2006
Location: southampton
Posts: 225
Max, i understand that. I am willing to do my bit to help you save fuel etc but what i am not willing to do is have my hands tied by a directive from some wally in a office telling me i must do it this way. It isn't sensible and they've tied it into environmental issues which it isn't about at all. The request for the trial AFAIK came from some of the airlines and is obviously about saving fuel while it costs so much. If you want to fly an economical speed then tell us. If you are at the front of a large queue then expect to be told to go faster than you want, but the number of times you are the front will be equalled by the number of times you are at the back.

Don't forget though that this is being treated as EGLL arrivals only, when infact the trial is for all LTMA inbounds. Whats the point of EGGW's doing 270kts when there is no holding and they are going straight in? Or EGLC's when 270kts is right at the top of their speed range? Its the blanket "All LTMA's must be doing 270kts to save the planet" rubbish that hacks me off.
1985 is offline  
Old 9th Jul 2008, 13:09
  #73 (permalink)  
 
Join Date: Oct 2005
Location: England
Posts: 2
Folks,

this proposal originally came from BA. Funnily enough, the points at which they proposed the 270 SLPs just happened to coincide with the EAT capture box for the TMA; in other words, BA (suits) were happy to fly balls-out to the capture box, then reduce speed to save a marginal amount of fuel (when compared to a transatlantic flight for instance), thereby guaranteeing their place in the queue. This matter was then raised at the OPA and the other airlines apparently agreed to it. The environment angle was introduced at a later stage, as initially the concern was the high cost of fuel.

As far as the speed restriction itself goes, it is NOT mandatory; ATCOs should only apply it in accordance with the current traffic situation. For example, if you have a bunch and are endeavouring to get them into a stream for the TC boys, then sod the 270kts - do what you have to do!

The first time i used the 270kts restriction, i had a BA pilot bitching at me about the reduction - not appreciated as i was very busy at the time. Said pilot was then advised (once the RT had quietened down a bit) about the origins of the restriction and sounded suitably embarrassed. Since then, i have refused to issue the instruction - if the airlines want this, why don't they instruct their pilots to do it and if it fits with my plans, great!!!

Quite frankly, whenever i can, i give 'when ready' clearances, thereby shifting the onus onto the flight deck to determine their optimum profile (i am not a pilot); unfortunately, sometimes i am unable to to do this and so have to use the ATC tools at my disposal to achieve a safe and orderly flow of traffic. It comes down to the fundamental question: efficiency vs capacity

With regard to the comment above about routeings, airspace changes/ old routes/new navigation: remember, it's not only Commercial Air Traffic that uses UK airspace - the military must also be given the space to do what they have to do, otherwise how can we as a country expect them to fight on our behalf? Also, any new airspace route changes are subject to the Airspace Change Process, which can be lengthy and costly, as well as being subject to public scrutiny - and let's face it, regardless of the environmental benefits a more direct route would realise, realistically, the general public only consider noise/visual pollution and have a 'Not In My Backyard' mentality.

Nuff said!
londoncontrol1 is offline  
Old 9th Jul 2008, 15:31
  #74 (permalink)  
 
Join Date: Jun 2001
Location: southampton,hampshire,england
Posts: 833
Selective benefits

Doubtless "Big Airways" will benefit from NATS preferential treatment. Others do not. I reckon Baby/Easy burn at least a third of a ton extra on every flight from Bristol to Scotland due level capping, and Ryan/Easy/Baby must burn at least an extra half a ton from Bristol to NI capped at FL240. I suggest that two days a week the level capping should be reversed and selected London-Scotland/NI's should be capped in favour of Bristol/Cardiff deps.
So far my personal experience of "270knots" indicates that there has been no effect on reducing stack holding....but there has been an increase in R/T loading on already congested frequencies.
Additionally....for years I've used my professionalism and experience to monitor stack delays....and my colleagues and I have informed the crews in timely manner and applied speeds as required.....but only when required.
055166k is offline  
Old 9th Jul 2008, 22:37
  #75 (permalink)  
 
Join Date: Apr 2000
Location: earth
Posts: 299
Regulated Airspeed trial - All flts inbound to LONDON TMA
will be required to fly a designated IAS in the descent of
270kts within an 80-100nm radius. Level clearances as
directed by ATC will not change and are mandatory.
This will result in improvements to average holding times
on arrival. Crews should note that holding and landing
sequences are set 40mins prior to arrival.This procedure
will not disadvantage your place in the arrival sequence

...may be look similar to an extract from our NOTAM brief

I don't like it from a pilot pov for reasons mentioned with regard to energy management. As LH we don't do this every day so there is some confusion as some pilots pre-plan a 270 kt descent and others the normal 300 kts ish (777) Sounds like its a roaring success. Mmmm
mr ripley is offline  
Old 17th Jul 2008, 13:06
  #76 (permalink)  
 
Join Date: Oct 2006
Location: Somewhere where I can watch you
Posts: 81
Originally Posted by dogma(elsewhere)
This involves flying the jet towards the best glide speed. Thomsonfly have worked with Nats to come up with a compromise speed for the London TMA of 270 kts in the decent.
- so now the ATC coal face knows who to blame Which dreamy-eyed, Latte-swilling suit at TF did this without airline-wide consultation? Hardly 'decent'
Flagon is offline  
Old 19th Apr 2021, 12:44
  #77 (permalink)  
 
Join Date: Jan 2012
Location: World
Posts: 68
I know this is an old subject, but does anyone know if the 270 kts instruction still applies on the London TMA?
Thanks!
busav8r is offline  
Old 20th Apr 2021, 06:52
  #78 (permalink)  
 
Join Date: Dec 2004
Location: Down South
Posts: 294
Not at the moment

In more normal times, it was a blanket 250kts if your delay went above 5 minutes at the holds unless we needed different speeds for the gaps. Delay predictions have got a lot better since 2008 though - there's tools that look out to 500 odd miles and start working out the order. It's not perfect, but it's way better than what we had 13 years ago.
The Many Tentacles is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.