Would it make more sense to land on the inners and depart on the outers
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Would it make more sense to land on the inners and depart on the outers
I know...the outers are shorter than the inners at CDG and LAX but what if the outers could be extended. For even runway lengths, is it better to have inevitable runway incursions on the landing runways where you can at least go-around instead of the present where a heavily loaded widebody is basically going have an accident of some sort if somebody cuts in front of them.
Opinions?
C-GTSO, an Airbus 330-342 aircraft operated by Air Transat, was conducting flight TSC397 from Paris/Charles de Gaulle, France (LFPG) to Montreal/Pierre Elliott Trudeau Intl, QC (CYUL) with 11 crew members and 308 passengers on board. After receiving their takeoff clearance and while lining up on Runway 27L at LFPG, the flight crew of TSC397 observed an Airbus 320 landing on Runway 27R. Before commencing their take off roll, both TSC397 flight crew heard ATC instruct the Airbus 320 flight crew to hold short of Runway 27L, and this restriction was read back correctly.
During TSC397's takeoff roll, at approximately 120 knots, ATC asked the Airbus 320 flight crew if they were stopped and instructed them to hold short a second time to which the flight crew replied that they were stopped and holding short of Runway 27L. When TSC397 passed the Airbus 320, the flight crew observed that it had stopped on the wrong side of the hold line.
Opinions?
C-GTSO, an Airbus 330-342 aircraft operated by Air Transat, was conducting flight TSC397 from Paris/Charles de Gaulle, France (LFPG) to Montreal/Pierre Elliott Trudeau Intl, QC (CYUL) with 11 crew members and 308 passengers on board. After receiving their takeoff clearance and while lining up on Runway 27L at LFPG, the flight crew of TSC397 observed an Airbus 320 landing on Runway 27R. Before commencing their take off roll, both TSC397 flight crew heard ATC instruct the Airbus 320 flight crew to hold short of Runway 27L, and this restriction was read back correctly.
During TSC397's takeoff roll, at approximately 120 knots, ATC asked the Airbus 320 flight crew if they were stopped and instructed them to hold short a second time to which the flight crew replied that they were stopped and holding short of Runway 27L. When TSC397 passed the Airbus 320, the flight crew observed that it had stopped on the wrong side of the hold line.
Well, if you land on the inners, then departing traffic has to cross the threshold of your runway to get to the departure runway. If the weather is IFR, they won’t be able to do that because they could interfere with the ILS. I’ve asked an ATC manager the same question and apparently there’s data that supports safer and more efficient ops overall with landings on the outers and departures on the inners.
It's generally accepted that landing on the outers and departing on the inners provides more runway capacity than the other way round.
Don't ask me why - maybe it's related to the considerations described in the previous post.
Don't ask me why - maybe it's related to the considerations described in the previous post.
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Well, if you land on the inners, then departing traffic has to cross the threshold of your runway to get to the departure runway. If the weather is IFR, they won’t be able to do that because they could interfere with the ILS. I’ve asked an ATC manager the same question and apparently there’s data that supports safer and more efficient ops overall with landings on the outers and departures on the inners.
It would be no interference if we can perform RNAV approach - unfortunately not available.
Usually TWR informs arriving traffic about crossing in progress but it does not help much.
And taxi out times are much longer nowadays.
So definitely less efficient runways' use. But maybe at least it's safer...
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Best solution is for landing traffic to land on the outer, take a central taxiway to the end and cross the departure runway at the very end - or even have the taxiway loop around beyond the runway. Amsterdam has that kind of arrangement on 18C/36C. Barcelona land on the inner and depart on the outer. They had so many runway incursions that they too introduced a system whereby departures would taxi across the landing runway only at the very end. In other words, no mid runway crossings.
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The world's busiest airport (by movements) is ATL. Land on the outers, then cross behind the departure runway to get to the terminal. With 883,680 movements last year (according to Wikipedia) they're obviously doing something right.
That number is down from 900,000+ in 2010
That number is down from 900,000+ in 2010
If you have traffic landing on the outer then queueing up on to cross the inner on multiple taxiways / crossing points, you can clear them all to cross the inner after a heavy / super departure effectively closes the inner runway for a couple of minutes to smaller traffic due wake.
The world's busiest airport (by movements) is ATL. Land on the outers, then cross behind the departure runway to get to the terminal. With 883,680 movements last year (according to Wikipedia) they're obviously doing something right.
That number is down from 900,000+ in 2010
That number is down from 900,000+ in 2010
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Landing on the outer and taking off on the inner is the standard procedure in busy airports in Asia. And it does make sense to me. If you are on short final on the inner, there is a serious risk of collision if let’s say you are on short final in IMC and at the same time an aircraft on ground is inadvertently crossing the inner runway to join the outer runway for take off.
When you land on the outer, you usually vacate close to the end of the runway, and even if you cross the inner runway by mistake and bad luck, an aircraft is taking off on the inner runway at the same time, he will probably be already airborne by the time he reached your position. You will be in big trouble but most important, probably still alive. xD
Plus using inner runway is more fuel efficient for departing aircraft.
When you land on the outer, you usually vacate close to the end of the runway, and even if you cross the inner runway by mistake and bad luck, an aircraft is taking off on the inner runway at the same time, he will probably be already airborne by the time he reached your position. You will be in big trouble but most important, probably still alive. xD
Plus using inner runway is more fuel efficient for departing aircraft.
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If I was designing the system, it would be predicated on the consequences of the most critical type of error. Obviously whoever uses the outer, has to cross the inner, and the error we're looking at is a runway incursion.
If the lander crosses while an A/C taking off is in a "line up and wait," there's less pressure on ATC since they are free to wait as long as they need to, before issuing the takeoff clearance. That puts less pressure on the situation since there's no time limit for the crossing plane to finish. If the crossing plane accidentally turns onto the runway instead of crossing (or simply gets stuck), the other plane on the runway is just sitting.
If, instead, the takeoff plane is crossing in front of a lander, there's a time limit forced by the approaching lander. So if the crossing plane stays on the runway too long, that forces a goaround which opens up the potential for the lander missing the goaround instruction, or starting it too late, etc.
So both of these reasons point to taking off on the inner and landing on the outer. I think every airport I've been to in the Eastern US does this, except Philadelphia.
If the lander crosses while an A/C taking off is in a "line up and wait," there's less pressure on ATC since they are free to wait as long as they need to, before issuing the takeoff clearance. That puts less pressure on the situation since there's no time limit for the crossing plane to finish. If the crossing plane accidentally turns onto the runway instead of crossing (or simply gets stuck), the other plane on the runway is just sitting.
If, instead, the takeoff plane is crossing in front of a lander, there's a time limit forced by the approaching lander. So if the crossing plane stays on the runway too long, that forces a goaround which opens up the potential for the lander missing the goaround instruction, or starting it too late, etc.
So both of these reasons point to taking off on the inner and landing on the outer. I think every airport I've been to in the Eastern US does this, except Philadelphia.
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The problem is if a lander crosses the departure runway while the takeoff is well started..
A flying airplane is much more manoeuverable than an airplane somewhere between 80kt and V1.
V1 guarantees you can brake and stop before the end of the runway, but not before the intermediate taxiway which the lander has used to misguidedly cross your takeoff runway.
A flying airplane is much more manoeuverable than an airplane somewhere between 80kt and V1.
V1 guarantees you can brake and stop before the end of the runway, but not before the intermediate taxiway which the lander has used to misguidedly cross your takeoff runway.
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That's true. It's a much more severe consequence of something that we're almost never exposed to (the safeguards against entering the runway when you're not supposed to, largely work.) On the other hand, the situations I described have less severe consequences, but we're exposed to those crossings virtually every flight. So I guess the final answer is trickier than I thought, because we'd have to actually get some numbers to plug into the risk equation.
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Best solution is for landing traffic to land on the outer, take a central taxiway to the end and cross the departure runway at the very end - or even have the taxiway loop around beyond the runway. Amsterdam has that kind of arrangement on 18C/36C. Barcelona land on the inner and depart on the outer. They had so many runway incursions that they too introduced a system whereby departures would taxi across the landing runway only at the very end. In other words, no mid runway crossings.
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As departures would cross the runway at the other end (2-3 km) from the localizer, the blockage would be limited, but would indeed be an issue under CATIII conditions. However, I do not think you are able operate closely spaced parallels under those conditions anyway.
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There is also a capacity issue to consider.
Crossing through a departure stream impacts less on the departure rate, as that can be adjusted quite finely to give the crossers sufficient time to get across
Crossing through an arrival stream means that the arrival - arrival separation must include time buffers in case the crosser takes longer than originally planned to get across. You always need to consider the worst case scenario.
With departures, you may need to occasionally delay take-off clearance if a crosser is dawdling, but you only need it for those rare situations, not every time.
The other consideration, in line with the Prevention of Runway Incursion document from ICAO, is that runway crossings should happen at a low energy point of the take-off run (i.e. as close as possible to the start of roll, not half way down the runway).
Cheers.
Crossing through a departure stream impacts less on the departure rate, as that can be adjusted quite finely to give the crossers sufficient time to get across
Crossing through an arrival stream means that the arrival - arrival separation must include time buffers in case the crosser takes longer than originally planned to get across. You always need to consider the worst case scenario.
With departures, you may need to occasionally delay take-off clearance if a crosser is dawdling, but you only need it for those rare situations, not every time.
The other consideration, in line with the Prevention of Runway Incursion document from ICAO, is that runway crossings should happen at a low energy point of the take-off run (i.e. as close as possible to the start of roll, not half way down the runway).
Cheers.
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In other words, no mid runway crossings.
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Interesting that nobody has noted that the real problem is the design of the airport terminals that require all aircraft to cross active runways to the central terminal buildings.
From a throughput point of view it would be far better to have multi-mode runways so as an aircraft touches down a departure lines up and as the arrival clears the runway the departure takes off to be airborne before next inbound is at 2 miles. There are no wake turbulence delays as the departing aircraft wake is not interfering with the landing aircraft and vice versa. Imagine if you like 4 Gatwicks alongside each other. So the airport has widely spaced non-interfering approaches to widely spaced runways with terminal buildings between each pair of runways linked by underground rail to the other terminals. Each terminal has two potential multi-mode runways alongside that will not require runway crossing after landing or before takeoff.
But why think about airport design let's make do with the way it's always been done.
From a throughput point of view it would be far better to have multi-mode runways so as an aircraft touches down a departure lines up and as the arrival clears the runway the departure takes off to be airborne before next inbound is at 2 miles. There are no wake turbulence delays as the departing aircraft wake is not interfering with the landing aircraft and vice versa. Imagine if you like 4 Gatwicks alongside each other. So the airport has widely spaced non-interfering approaches to widely spaced runways with terminal buildings between each pair of runways linked by underground rail to the other terminals. Each terminal has two potential multi-mode runways alongside that will not require runway crossing after landing or before takeoff.
But why think about airport design let's make do with the way it's always been done.