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forget about saving fuel

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forget about saving fuel

Old 11th May 2010, 10:55
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Originally Posted by rubik101
It would be interesting to see if such a system would work for all the London airports, 2 hours of just arrivals, then 2 hours of just departures. It would certainly make flow control a lot simpler
This is, of course, a variation on what effectively happens at Hub airports in the US, where carriers based there schedule a massed arrival over a short period of both mainstream and commuter flights, employing as many runways as practical, followed by connecting passengers all interchanging, and then mass departures in similar style. The arrivals at the larger points tend to be concentrated in about a 30 minute window, then 30 minutes with all gates occupied, and 30 minutes of departures. A little later the whole cycle starts again.

Possibly someone at Berlin in 1948 looked out and said "one day my grandson will organise the same as this at Dallas".
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Old 11th May 2010, 11:03
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What would really helpm is if the Loco''s (harps and slezy and the yorkshire puddings) would stop requesting directs to try and make up time in their unrealistic schedules!
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Old 11th May 2010, 11:29
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What would really helpm is if the Loco''s (harps and slezy and the yorkshire puddings) would stop requesting directs to try and make up time in their unrealistic schedules!
What's wrong with asking for direct routings? What's the worst can happen - ATC says no. After all, Eurocontrol are paid for their services. And a direct routing can be as equally helpful to them as it is for the aircraft in question.
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Old 11th May 2010, 14:13
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Originally posted by BOAC:
had to make landing and departure windows (primarily due to apron space)
This is one important element in the mix that a lot of people forget.

If you arrive 10 minutes ahead of schedule it will probably mean that your stand will be occupied by someone else.

If your airport is shifting 60 movements an hour and you have 60 stands, and your average turnaround time is 60 minutes, then everything is hunkey-dorey.

Add another movement, brought about by direct routing, into this equation making 61 movements and then someone is always going to be waiting, be it on the ground or in the air.

When circumstances outside the norm happen involving inbound diversions then your 60 stands, which couldn't cope before with 61 movements now lead to parking on taxiways or even runways.

Most major airports around the world are currently working at or close to capacity, which for them means that if ATC increase the movement rate then the airport infrastructure can't cope and delays occur. Unfortunately, these tend to get blamed on ATC when in a lot of cases this is not the true picture.

I've lost count of the number of times that I've flown into Heathrow early and had to hold on the taxiway waiting for a stand to become available.

Direct routings only help if they get aircraft back on schedule. If they get you ahead of schedule then you better check ahead to see if the stand at your destination is available. That's why airports have scheduling so that they don't accept more aircraft per hour than can be handled on the ground.

At a lot of airports the theoretical ATC movement rate far exceeds the airports actual ability to handle these movements.

So, although ATC can and do frequently offer direct routings, the end result may not be what you were expecting.
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Old 11th May 2010, 14:15
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With many years of flying for both easy and Ryanair I have to say that the schedules are fairly generous. Even departing 5-10 minutes late we would almost always arrive on time, not that we ever laft late of course! I'm sorry if some of you in the real airlines choose to believe otherwise but the truth is that everyone asks for direct routings and whenever possible, ATC will comply.
But this dispels the myth held by the likes of 'unablereq....er?' and others like him that the 'Locos' are some sort of inferior, squalid and always unproffessional beings and should be frowned upon and for that I can only apologise on their behalf.
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Old 11th May 2010, 14:43
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What's wrong with asking for direct routings? What's the worst can happen - ATC says no.
The problem is, in most cases these days its impossible to give a rational and reasoned response to such requests as an individual controller working a small piece of airspace.
Sure you might sound like the good guy at the time giving direct to every exit point in your airspace but have no idea of the problems you may have caused downstream, as noted by On the Beach.
The point is, in the absence of sufficient information to the contrary, why not just fly the flight plan?

All too often the phrase " Track direct xxxxx [expect to get in the terminal area]" seemed to come true in my 34 years of experience as an ATC and ATPL.
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Old 11th May 2010, 15:19
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P.S. Showing my age, but it brings to memory my early days as radar controller on the Melbourne-Sydney route. Instead of tracking via the published route, most jets would ask for the direct track from one VOR to another VOR about 200 miles apart, shaving off about 3 or 4 miles theoretically. Due to the mountainous terrain,the radials scalloped so badly that we would watch most aircraft add about 10 miles to their track instead of accurately tracking via the perfectly good intermediate navaid.

Although navigation is obviously vastly better these days, the overriding principle remains that in most cases a lack of available information and blind hope make for totally irrational decisions while making you feel like you're achieving something.

Last edited by bekolblockage; 11th May 2010 at 15:29.
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Old 11th May 2010, 15:28
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The problem is, in most cases these days its impossible to give a rational and reasoned response to such requests as an individual controller working a small piece of airspace.
I'm not looking for a rational or reasoned response. If they oblige my request I extend my thanks, if they decline then I respect the fact that they have every jurisdiction to do so.

Direct routings only help if they get aircraft back on schedule. If they get you ahead of schedule then you better check ahead to see if the stand at your destination is available. That's why airports have scheduling so that they don't accept more aircraft per hour than can be handled on the ground.
I respect what On the Beach has to say. Totally true but very dependent upon where you are operating to and the time that you are operating. Obviously the likes of LHR, MAD, CDG etc are lost causes because becoming ahead of schedule ultimately ends up on schedule or behind due to capacity.
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Old 11th May 2010, 16:57
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Angry

Most 'professionals' here just do not grasp the magnitude: one flight from India to Europe will save an average of 8 minutes of flight time thanks to short cuts, one way; on an A340 this amounts to approx. 800kg of fuel, and an all over average saving of about 280 Euros. Multiply this by 365 flights per year, you come up with some 100,000 Euros saved, on one single route, or vv. 200,000 Euros. This is s.th. to write home about, alas we do it every day.
IMHO only people who cannot understand this may be called locos etc.
(How I wish this forum was reserved for real pro pilots! )
Hic!
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Old 11th May 2010, 17:42
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. . .why not just fly the flight plan?
. . . because most pilots wish to avoid making turns in cruise. The worst, totally pathetic airway structure are the high altitude sectors between KBL-LHE-DEL-AGG. All the turning would even make a cat dizzy.
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Old 11th May 2010, 18:07
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Today 55-60a/c per hour per sector is max. So if the less busy sectors down the route give a direct to everyone , some will get early and a sector-funnel down the line will get 65 or 70 and that becomes a safety issue.
Same reasoning with RFLs. If everyone request 350+ cruising to CFMU , you get delays, but if the mid sector 290-340 is less busy , airline X might want to refile a lower cruising level to get no delay through that area.
Pilot still like higher of course, but if the controller obliges the system no longer works.
Difficult transition times between controllers trained the old way and the maximizing capacity issues of today
Atcwatcher, I'm just a simple soul.
You say that me arriving 2 minutes earlier at your sector might take you over the max. That's easy to understand, if all traffic was strictley time-scheduled.

However, would you not agree that other factors have a far far greater impact on this? If by some miracle everyone shows up on time at the gate I'll depart five minutes ahead of schedule. Combine that with departing from runway 26L in stead of 08R in LGW and I'll be over your sector a full 15 minutes earlier than planned. That totally dwarfs the effect of directs in my view. Correct? But these directs still give me a significant fuel saving.
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Old 11th May 2010, 19:29
  #32 (permalink)  
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Penko :
departing from runway 26L in stead of 08R in LGW and I'll be over your sector a full 15 minutes earlier than planned.
Not quite correct ,because in this example/configuration with that capacity , my sector will be regulated and you'll be on a CTOT.

Again I am fully for direct routes, did it for 30 years, problem is that saving fuel ( the title and subject of this post) is no longer the airline's #1 priority. Departing/Arriving on time without delay is, and that changes the game.
Longer routes and lower cruising FL are filed by your OPS to avoid delays, requesting direct or higher while in the air and the system no longer works.

In my years as a controller my "custommer" was the pilot, today it is he aircraft operator . Big , big difference.
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Old 11th May 2010, 19:50
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While passenger in a UA flight to Heathrow, and listening to the cockpit transmissions on Channel 9, I heard an American Airlines pilot ask for Direct to Bovingdon.....

The London Controller said he couldn't approve that because it would take the AA flight directly through a Military Danger Zone...

Whereupon another Yank on frequency suggested "Go for it!"

Lovely!
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Old 11th May 2010, 20:46
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ATC-Watcher, thabks for the explanation

I think it is time for another ATC centre visit/ATCO''s visiting the flightdeck!
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Old 11th May 2010, 22:08
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Sitting on the taxiway with one engine shutdown and the other at ground idle is a lot cheaper per minute than any airborn flight schedule.
I couldn't agree more, Gus, and the point I was trying to make was that it's the lack of ground infrastructure in many cases that is causing your and many other airlines to waste money burning fuel unnecessarily.

Direct routings, as I've said before are often offered by ATCs, but there's not much point if it just gets you into the hold 2 minutes earlier and you then spend an extra 2 minutes holding, or it gets you on the ground 2 minutes earlier and you then wait for 2 minutes for your stand to become available.

I appreciate you would prefer the ground holding option to the airborne option, as I'm sure most ATCs would, apart from the Ground Movement Controllers, of course.

As traffic starts to get back to pre-banking crisis levels it will be airport infrastructures and not ATC that will be the cause of most of your delays, so enjoy your direct routings whilst they last.
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Old 12th May 2010, 08:09
  #36 (permalink)  
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I do not see why, in this 21st century, we cannot develop a system whereby a/c are allocated and issued en-route with 'gates', either at FIR entry or at holding beacons. It will take some significant software writing to absorb all the inputs but certainly do-able from an ATC p.o.v. I would have thought. It would just be a step forward from the Pristina plan I posted earlier. and not too different to (from for the purists) EOC's/EFC's.

Get there early you hold until, get there late you hold and re-join the queue later. Most crews and equipment should be capable of monitoring progress, adjusting speeds and hitting the window. Not rocket science. On second thoughts, from what I have seen.....................................
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Old 12th May 2010, 08:24
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BOAC, your "gate" proposal already exists. It is your filed flight plan including filed requested levels and filed mach number combined with your CTOT.

IF2
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Old 12th May 2010, 08:41
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Direct routings, as I've said before are often offered by ATCs, but there's not much point if it just gets you into the hold 2 minutes earlier and you then spend an extra 2 minutes holding, or it gets you on the ground 2 minutes earlier and you then wait for 2 minutes for your stand to become available.
The point I was trying to make earlier is that there's no guarantee that you won't get the 2 minute hold and the 2 minute gate hold anyway. Flow management is not that precise (yet). So, you might as well take the direct. You stand just as much chance of avoiding delay further down the line as you do getting it.
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Old 12th May 2010, 08:47
  #39 (permalink)  
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Itchy - I am talking PRACTICAL flow control, not THEORETICAL, as per this thread?
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Old 13th May 2010, 04:01
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CTOT is variable from -5 to +10 minutes, that is a 15-minute period, and this game will never be more precise. Then you might take off in the wrong direction due to wind, which might add another 10 minutes, and your actual flight plan is of CTOT+20, and so on. I reckon ATC must learn to live with that...
At least, depriving aviation of fuel savings by denying directs will not improve anything.
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