Investigation Into Hold-ups on the approach.
Basically for a university assignment we have to perform a presentation, I have teamed up with some buddies and our given topic was
"Investigate the Causes and effects of aircraft being held up for long periods during the approach to major airports." We already have a few topics covered such as the PNB system, but if anyone with relevent experience could give us a bit of guidance or information, we would be very grateful! Many thanks The Team! |
Quite simple really...
Imagine a large car park with only one exit, which leads to another large car park. Everyone from one car park wants to get into the other car park at the same time...however, obviously only one can use the exit at a time. Holding is created because everyone wants to land at the same time. |
For a minute there I thought you were talking about a modern day Highwayman...
Then I thought you might be talking about the underwear preference of the Cabin Crew. Turns out you just want someone to confirm that the airports often run at near capacity |
Gaps for departures,vortex wake spacing,bad weather causing increased spacing,varied traffic mix and too much traffic.Fog below landing limits,snowclosed,runway blocked or getting inspected.There you go.Oh and my bad vectoring.:ok:
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Turns out you just want someone to confirm that the airports often run at near capacity |
Wow thats a nice topic...
Reasons, as being said... Equipment
If you want more ... just tell me :O |
Bookworm - there will always be holding.
Being held on the ground before departure is OK for short flights, but not for medium to long haul flightsd - too many variables en-route. flying more slowly and efficiently enroute. Complete rubbish because all it did was made the same aircraft turn up to the holds in a bunch, just a couple of minutes later than they would have normally. You need speed differentials to prevent holding. Yes, sequencing could be done from further out - NATS are developing equipment thta will give the EAT of every A/C inbound to LTMA airfields - this may help en-route to stream them more efficiently for TC (by the time A/C hit TC airspace, there is little time/room to stream effectively). However the problem will still exist to an extent as AC get the A/C late (and the very fact that UK airspace is actually pretty miniscule for what it achieves). Similarly, different AC sector groups control A/C inbound to the same hold, but you can bet they won't consult each other about streaming 3 or 4 flows into one, because they have not got the time. Some improvements are possible, but your answer is too simplistic. In theory, a good idea, but to achieve it... BravoMike idea of flow is to keep us controllers working with a constant flow ( maximum traffic without holding) Obviously when something happens to that runway, for example as mentioned in your very good post, then holding starts to increase hugely. On Normal dyas, flow worksto a degree, but putting measures on to counter say, an incident, take time - and are only really effective for short haul flights... everything else is already in the air and inbound!! Saying that, the message could be passed down th eline to external agencies to slow things up for us, but that does not always work, as they either want to get rid of traffic ASAP, which means getting it our of their airspace, or they have their own issues to deal with i.e. it is just to difficult. |
Some improvements are possible, but your answer is too simplistic. In theory, a good idea, but to achieve it... |
Not negative, just realistic about what can be achieved in the LTMA!! As a TC controller I would love to have a bit more of the streaming done earlier on and correctly for what will happen at the end, i.e. on the runway. However the AC guys don't have the time nor the huge blocks of airspace within which to achieve this.
There can be some improvements, but not to the extent of cancelling holding in normal day to day operations. If the UK had huge amounts of airspace to allow for lots of track miles, streaming would be better, but it doesn't. If we can get Functional Airspace Blocks, whereby the procedures routes etc of surrounding ANSPs etc were all tied up togwether, then it would help... can't see that happening for a while though. |
First of all Holdings are not meant to be used in a normal circumstances. For some reason London is the only ANSP that consider them as a part of the approach. Trying to sequence A/C from holding patterns could cause major problems in case something goes wrong. We have seen that several times so far. CFMU is giving them 45 A/C per an hour but in reality they are only landing 37 A/C. Somebody mentioned before in one of the chats that London is developing the software to act on the A/C coming from the Europe in order to "stream "them. I have to say that this is exactly what CFMU has been doing for the last 15 years. I have a feeling that CFMU and London should sit down and try to find compromise on how to go ahead in Air Traffic Flow Management for the future.:)
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Not negative, just realistic about what can be achieved in the LTMA!! |
Bookworm,
you are correct... large scale 'joined up thinking' with all the european states would be needed to make the best go at a decent system... it might happen in the future, but one of the difficulties will be getting countries to relinquish sovereign airspace... Flowman the system NATS is bringing in is more along the lines of an extended EAT display, allowing controllers to see what the EAT is for each aircraft and to (hopefully) allow them (the controllers) to issue speed instructions etc that tie in with the EAT, to minimise or negate holding. The problem could be getting adjacent stand alone sectors talking to each other when they are controlling aircraft inbound to the same hold facility... it could cause more problems for the TC guys instead of alleviating them, time will tell. If it goes to plan, it will actually be a great benefit. As for holding in the LTMA - to gain the best and most efficient use of a runway that has over 90% occupancy rates, you need to have a constant supply of aircraft to vector onto final. That is why Heathrow runs best (most efficiently) when it has a few aircraft in the hold. Remember we are purely talking about the efficiency of runways here, when you have a dedicated landing runway. |
If you do research on the following:
"Investigate the Causes and effects of cars being held up for long periods during the approach to major cities" .....you will probably end up with the same core results! |
Altho a humble pax I think it is worth adding that many major airports delay approaching aircraft but do not use holding as muchas say LHR does. The reasons for this are I am sure those explained here that there is ahuge concentration of aircraft movments in SE England .I belive London as a city has the most air ransport mvements f any city in the world.
Also a very large proportion of the traffic comes from the South or EAst where the airtraffic control boundaries with France Netherlands etc are in terms of the speed aircraft virtually adjacent to the London Terminal Area. In many other countries the main city is well away from the borders and theres often more space to sort ths out in. I make ths comment because going to Frankfurt fairly often we fly past the airport at quite a height and contine heading away from t for miles and miles and miles. No holding patern which passengers notice but just a huge detour so ATC can sequence everybody for the runways Good luck with your project but I think yoare going to find that its no different to the M25 ona friday-two many vehicles not enough space PB |
As for holding in the LTMA - to gain the best and most efficient use of a runway that has over 90% occupancy rates, you need to have a constant supply of aircraft to vector onto final. That is why Heathrow runs best (most efficiently) when it has a few aircraft in the hold. To create a constant supply of aircraft to vector on to final, you don't necessarily need holding stacks (stock). But you do need a more joined up ATC system than we have today, with its own form of Kanban. |
Bookworm, your analogy isn't great. With a dedicated landing runway a 'stock' of aircraft is required to provide the most efficient landing order in terms of wake vortex categories (and keep up the pressure on FIN!)
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Bookworm, your analogy isn't great. With a dedicated landing runway a 'stock' of aircraft is required to provide the most efficient landing order in terms of wake vortex categories Come on guys, use a little imagination... |
Too many aircraft trying to arrive and land at the same airfield at the same time. It happens at every airfield sometimes (even the much vaunted AMS) because demand is higher than capacity at that time.
The reason there is always holding at EGLL is due to lack of runway space, lack of airspace to stream in and that it is always operating at close to capacity. One little delay of any sort can cause problems. Somebody mentioned before in one of the chats that London is developing the software to act on the A/C coming from the Europe in order to "stream "them. I have to say that this is exactly what CFMU has been doing for the last 15 years. I have a feeling that CFMU and London should sit down and try to find compromise on how to go ahead in Air Traffic Flow Management for the future The new software for the LTMA will only be a good as the people using it. What happens if the kit tells me that ABCXXX should be infront of BCDXXX and its physically impossible to do that? |
1985
even worse - don't know what sector you work, but how is it going to work when you have two totally stand alone sectors (23 and 22) sorting out between them an order for say the OCK stack - they would have to be constantly in communication with each other!! Constantly second guessing each other will not work - as if you had the time for it anyways!! |
I think 1985 might try to work Clacton at some point :E
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