runway change from ATC's point of view
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runway change from ATC's point of view
Hi folks,
I was wondering if someone could explain the whole process of a runway change from atc's perspective in big airports with lots of incoming traffic. For example, let's say the wind changed 180° and tower changes from rwy.18 to rwy.36, my questions are:
-What happens to the ones already flying the STAR for the old rwy, do they get vectors for the new one? or still land on the old one although with some tail wind?
-From which point on the map does atc say which airplane still lands on the old and the rest on the new one?
-How do they avoid conflicts between possible go arounds from the old rwy and approaches into the new one?
-How do they deal with departures?
-And last, is there some kind of established criteria or checklist for the controllers to say "ok, now we're switching rwys"?
As you can tell I have little clue of what proceeds in this case, but i'm sure it has to be a big deal for atc!
Thanks in advance for the help
I was wondering if someone could explain the whole process of a runway change from atc's perspective in big airports with lots of incoming traffic. For example, let's say the wind changed 180° and tower changes from rwy.18 to rwy.36, my questions are:
-What happens to the ones already flying the STAR for the old rwy, do they get vectors for the new one? or still land on the old one although with some tail wind?
-From which point on the map does atc say which airplane still lands on the old and the rest on the new one?
-How do they avoid conflicts between possible go arounds from the old rwy and approaches into the new one?
-How do they deal with departures?
-And last, is there some kind of established criteria or checklist for the controllers to say "ok, now we're switching rwys"?
As you can tell I have little clue of what proceeds in this case, but i'm sure it has to be a big deal for atc!
Thanks in advance for the help
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The STAR for most major airports is good to the holding fix. After that it's usually radar control. However, without radar the traffic would simply hold until the new runway was available and then commence approach.
The decision about which aircraft use the new runway is usually based on time. I.e. a decision is made to change runways at 14:35, so everything up to about 14:34 lands on the old runway and from 14:35 onwards they use the new one. It's very easy to do that under radar control but without radar there would usually be some delay.
Go-arounds against opposite direction arrivals... ATC would issue appropriate instructions to separate the aircraft.
How do they deal with departures?? The last one takes off at 14:34 from the old runway and the first one on the new runway goes a minute or so later. ATC provides separation between any conflicting traffic.
Runway changes depend on the weather. When a decision is made to change runways ATS usually has a long checklist of agencies to inform, eg the ATC Centre, safety services, etc. Runway changes at a major airport can take half an hour or more..
The decision about which aircraft use the new runway is usually based on time. I.e. a decision is made to change runways at 14:35, so everything up to about 14:34 lands on the old runway and from 14:35 onwards they use the new one. It's very easy to do that under radar control but without radar there would usually be some delay.
Go-arounds against opposite direction arrivals... ATC would issue appropriate instructions to separate the aircraft.
How do they deal with departures?? The last one takes off at 14:34 from the old runway and the first one on the new runway goes a minute or so later. ATC provides separation between any conflicting traffic.
Runway changes depend on the weather. When a decision is made to change runways ATS usually has a long checklist of agencies to inform, eg the ATC Centre, safety services, etc. Runway changes at a major airport can take half an hour or more..
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Heathrow Director's experience is of British STARs of course! Elsewhere, they often (perhaps usually) go all the way to the Final Approach Course Fix, around 10 nm final, or to a Downwind Termination Waypoint abeam final to a specific runway.
For us, there are two basic scenarios for a runway change. The planned change occurs when the wind is light enough to allow downwind operations until traffic allows, or when we expect the wind to shift significantly and we have the opportunity to change runways in advance.
In this case, the key is to find a natural gap in the arriving traffic, such that no more than one or two aircraft will have to hold outside the CTA. Coordination with the tower should result in the right number of departures heading for the existing runway direction to fit the arrivals in or close to the CTA which will stick with the existing runway direction.
An unplanned runway change will usually occur when the wind has suddenly shifted, perhaps leading to one or two go-arounds. In this case, the first reaction is to stop more arrivals entering the CTA. The hold is the safest place for them if the CTA is already close to capacity. If there are departures which can accept the tailwind component and which are more efficiently dealt with by getting them airborne from the exisiting runway direction, the likelihood is that they will be kept fairly low while the arrivals are vectored for the other end. Other departures will either be taxied for the other end or kept on stand until the runway change is complete.
Conflictions between go-arounds and arrivals really should not occur. If the published go-around is to 3,000 ft, arrivals will be kept at or above 4,000 ft until the last arrival has landed on the original runway. Likewise, arrivals will be kept 1,000 ft or more above the altitude to which departures climb on the SID.
As HD says, there is a checklist involved so that everyone is in the loop. While a quick runway change mandated by weather can be hard work, it is not a seat-of-the-pants thing. Separation is assured not just against the traffic you currently have, but also against departures not yet airborne and against possible go-arounds.
For us, there are two basic scenarios for a runway change. The planned change occurs when the wind is light enough to allow downwind operations until traffic allows, or when we expect the wind to shift significantly and we have the opportunity to change runways in advance.
In this case, the key is to find a natural gap in the arriving traffic, such that no more than one or two aircraft will have to hold outside the CTA. Coordination with the tower should result in the right number of departures heading for the existing runway direction to fit the arrivals in or close to the CTA which will stick with the existing runway direction.
An unplanned runway change will usually occur when the wind has suddenly shifted, perhaps leading to one or two go-arounds. In this case, the first reaction is to stop more arrivals entering the CTA. The hold is the safest place for them if the CTA is already close to capacity. If there are departures which can accept the tailwind component and which are more efficiently dealt with by getting them airborne from the exisiting runway direction, the likelihood is that they will be kept fairly low while the arrivals are vectored for the other end. Other departures will either be taxied for the other end or kept on stand until the runway change is complete.
Conflictions between go-arounds and arrivals really should not occur. If the published go-around is to 3,000 ft, arrivals will be kept at or above 4,000 ft until the last arrival has landed on the original runway. Likewise, arrivals will be kept 1,000 ft or more above the altitude to which departures climb on the SID.
As HD says, there is a checklist involved so that everyone is in the loop. While a quick runway change mandated by weather can be hard work, it is not a seat-of-the-pants thing. Separation is assured not just against the traffic you currently have, but also against departures not yet airborne and against possible go-arounds.
Where I work (Oz) runway changes are normally a coordinated change between Tower and Approach and this will often be after Approach has advised pilots of the downwind component and ascertained if they can still accept the old runway or not. Occasionally, the wind change is drastic enough for an immediate change of runway to be required.
So, normal procedure is we agree on which arrival will be last to use the old runway. Aircraft for current runway keep their STAR (Our STARs continue to the instrument approach or all the way to the runway for visual approach).
Departures will use the current runway until the runway change. If they can't accept the downwind component they will have to wait til the runway change occurs. Arrivals have priority over departures.
Arrivals that can't accept the downwind will be given a new landing slot to the new runway and would normally be given a new STAR. If they are close in they will just be vectored to the new runway.
There are various criteria for deciding if a runway change is required. Some examples are: More than 5 Knots downwind; Any downwind on a wet runway.
Most jet pilots will happily accept 10KT downwind (and often considerably more on a dry runway) especially, if it means you keep your landing slot.
This is the basics only, there are a lot more variables in the decision.
So, normal procedure is we agree on which arrival will be last to use the old runway. Aircraft for current runway keep their STAR (Our STARs continue to the instrument approach or all the way to the runway for visual approach).
Departures will use the current runway until the runway change. If they can't accept the downwind component they will have to wait til the runway change occurs. Arrivals have priority over departures.
Arrivals that can't accept the downwind will be given a new landing slot to the new runway and would normally be given a new STAR. If they are close in they will just be vectored to the new runway.
There are various criteria for deciding if a runway change is required. Some examples are: More than 5 Knots downwind; Any downwind on a wet runway.
Most jet pilots will happily accept 10KT downwind (and often considerably more on a dry runway) especially, if it means you keep your landing slot.
This is the basics only, there are a lot more variables in the decision.
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While a quick runway change mandated by weather can be hard work, it is not a seat-of-the-pants thing.
When the thunderstorms roll through in the summer months it is not uncommon to go through all 4 runway configs in the space of 30 mins (05/06s to 15s to 24s to 33s) as you desperately try to chase an into the wind landing...or avoid lightning and CBs on final. In these cases we are just using vectors and altitude as the STARS will have been cancelled (as they usually fly right into the storms) and departures will be stopped (as they want to turn right off the deck thus not being on the SID).
Outwith the "extreme" scenario I agree with everything else mentioned. A standard runway change will normally be coordinated between tower and the terminal..and in the case of YYZ can normally be arranged when there is a "gap" in arrival traffic. Procedures are then as mentioned by other posters.
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Not meaning to contradict you, M-A-Canuck, but by "not seat-of-the-pants", I certainly don't mean a runway change can't be fraught and take all concerned to the limits of their abilities! What I DO mean is that assurance of separation is NOT thrown away.
Ludocivo's original post appears to assume that an arrival for the opposite end might be cleared for an approach when their is still the possibility of a go-around from the original end. I hope I can speak for all of us when I say that if an aircraft is put on final to the new, opposite end, when there is still an aircraft on final to the original end, it will NOT be cleared for the approach and it will be kept at an altitude vertically separated from the go-around altitude. Where terrain separation as well as traffic is not an issue, the go-around altitude may be altered from standard to allow a lower altitude, still separated above, for the aircraft on final to the new end, but separation will still be assured until the aircraft in the original direction has landed.
Ludocivo's original post appears to assume that an arrival for the opposite end might be cleared for an approach when their is still the possibility of a go-around from the original end. I hope I can speak for all of us when I say that if an aircraft is put on final to the new, opposite end, when there is still an aircraft on final to the original end, it will NOT be cleared for the approach and it will be kept at an altitude vertically separated from the go-around altitude. Where terrain separation as well as traffic is not an issue, the go-around altitude may be altered from standard to allow a lower altitude, still separated above, for the aircraft on final to the new end, but separation will still be assured until the aircraft in the original direction has landed.
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Regarding CDG (quite a busy airport I may say), two situations may occur :
- the pilots start reporting some tail wind, and the weather forecasters (who said fortune tellers ?
) tell us that it's not temporary and the wind is actually shifting ; then we'll wait for the end of the arrival peak if any and only afterwards perform the runway shift : it's easier to block departures on ground for 10-15 minutes during the shift than to keep 60 incoming aircrafts in the holding patterns while they weren't initially suppose to hold...
So, coordinating approach and tower, we decide of an hour for the shift, say 14:30. Around 14:15, 14:20, regarding to the traffic, the ground will start rerouting the departures to the new rwy holding point (well, not too close to avoid blocking the last arrivals vacating the rwy)... At 14:15, the incoming arrivals will be hold in the stacks. At 14:25, the approach will release the first arrivals in the new configuration ; the last arrival should land at 14:30, just afterwards the take-offs start again...
- the wind shift is stronger, with aircrafts going around due to the back wind for example, or when a thunderstorm front has swept the airport. Then we have no choice but to act immediatly, everybody is stacking until the new runway configuration is available ! In case of a thunderstorm, it may happen that we need to shift twice in a row... I've seen once an Alitalia lining up, but refusing to take off due to the back wind... he was to be the last taking off facing West... "No problemo", he vacates the rwy, taxies to the other end, queues behind the other... but when it's about to be his turn... the wind has turned again, and we have to face West once again... so he taxies back to his initial holding point... and happens to be number 15 when he arrives there... When we've been able to start departing facing west again... we've allowed him to backtrack the rwy a short while to pass the others and to depart as #1 : he had been fair play all along, never complaining, we couldn't do less !
- the pilots start reporting some tail wind, and the weather forecasters (who said fortune tellers ?
) tell us that it's not temporary and the wind is actually shifting ; then we'll wait for the end of the arrival peak if any and only afterwards perform the runway shift : it's easier to block departures on ground for 10-15 minutes during the shift than to keep 60 incoming aircrafts in the holding patterns while they weren't initially suppose to hold...So, coordinating approach and tower, we decide of an hour for the shift, say 14:30. Around 14:15, 14:20, regarding to the traffic, the ground will start rerouting the departures to the new rwy holding point (well, not too close to avoid blocking the last arrivals vacating the rwy
)... At 14:15, the incoming arrivals will be hold in the stacks. At 14:25, the approach will release the first arrivals in the new configuration ; the last arrival should land at 14:30, just afterwards the take-offs start again... - the wind shift is stronger, with aircrafts going around due to the back wind for example, or when a thunderstorm front has swept the airport. Then we have no choice but to act immediatly, everybody is stacking until the new runway configuration is available ! In case of a thunderstorm, it may happen that we need to shift twice in a row... I've seen once an Alitalia lining up, but refusing to take off due to the back wind... he was to be the last taking off facing West... "No problemo", he vacates the rwy, taxies to the other end, queues behind the other... but when it's about to be his turn... the wind has turned again, and we have to face West once again... so he taxies back to his initial holding point... and happens to be number 15 when he arrives there... When we've been able to start departing facing west again... we've allowed him to backtrack the rwy a short while to pass the others and to depart as #1 : he had been fair play all along, never complaining, we couldn't do less !
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In Oslo we do it the easy way
We determine the minute of last landing/Departure and who this will be. (Normally time for change is set 20 minutes after TWR inform us we need to change RWY)
Then we just hold at start point of STAR for 10 minutes (little depending on the lenght of the STAR) and start arrivals into the new runways at normal rate. This way we will have first landing on new RWY at about 20trackmiles from Touchdown when last opposite departure is airborne..with the arrival "pressure" up again to normal from first landing.
In low traffic periods, we do it more manually and find a good time in traffic to do it with some delaying vectors on the innbounds.
However the "fun" starts on the days you have to make instant changes due to rapid windchange from CB's and so on
Then we will normally have planes on vectors everywhere in a controlled caos 
We determine the minute of last landing/Departure and who this will be. (Normally time for change is set 20 minutes after TWR inform us we need to change RWY)
Then we just hold at start point of STAR for 10 minutes (little depending on the lenght of the STAR) and start arrivals into the new runways at normal rate. This way we will have first landing on new RWY at about 20trackmiles from Touchdown when last opposite departure is airborne..with the arrival "pressure" up again to normal from first landing.
In low traffic periods, we do it more manually and find a good time in traffic to do it with some delaying vectors on the innbounds.
However the "fun" starts on the days you have to make instant changes due to rapid windchange from CB's and so on
Then we will normally have planes on vectors everywhere in a controlled caos
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Have you noticed how the CB love to bother with your stack patterns, so that you have to create stacks in the middle of nowhere, with an acft choosing to make it right hand, the next left hand, the third one... makes some "8" patterns...
Of course, if the traffic is really low, we'll also do it fast and manually... but the CBs are of a curious character, and always want to see what happen when they visit us at hub times...
Of course, if the traffic is really low, we'll also do it fast and manually... but the CBs are of a curious character, and always want to see what happen when they visit us at hub times...
