How dangerous is a single runway, major airport?
I gave this some thought when I was still flying, and I did wonder about arriving back at, say LGW or MAN (before the second runway was built) at peak periods, with management trying very hard to get us to carry ‘plog’ fuel.
My concern was that if the main drag was blocked then all would have to divert. But to where, given that Liverpool, our primary diversion would be very busy with the lowest cost carriers? Leeds would have very little capacity to offer and Doncaster had not yet opened. Much the same with LGW and the airfields there.
I reckoned there would have been some very tight ‘sphincters’.
My concern was that if the main drag was blocked then all would have to divert. But to where, given that Liverpool, our primary diversion would be very busy with the lowest cost carriers? Leeds would have very little capacity to offer and Doncaster had not yet opened. Much the same with LGW and the airfields there.
I reckoned there would have been some very tight ‘sphincters’.
I have no experience with Gatwick however I bet The second runway there can be used to increase capacity. At such airport where parallel rwys are too close to allow for simultaneous approaches, One is used for departure and other for arrivals. This increases capacity because it allows for one aircraft to line up while the other is still on approach. As the landing aircraft touches down, the departing aircraft can commence takeoff.
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The only way I could see that happening is to use 26L for take-off and 26R for landing. But I think the taxiway too is close to 26R. I suppose you could put a large holding area where the fire training is so a few aircraft could land and hold, and then all taxi in one behind the other while 26L was used.
Lots of debate on the detailed workings here on PPRuNe when the plan was first unveiled about 2 years ago.
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Only half a speed-brake
while at the same time
completely close 12/30 and thus remove the noise burden on the west side of the city
sounds like a fair one.
The argument about single runway being not safe does sound silly, however. Apart from the the reasons already mentioned, also because if 24L will not be built the 12/30 is not getting closed!
Anyway, back to your dilemma: If there is a major accident that closes a runway, the attending fire and rescue services cannot provide sufficient cover to sustain operation on the other runway anyway. They will re-group but for a certain period of time 20-40 minutes at least nothing else moves. Some will not be allowed to depart on time, some will need to divert or decide to wait and then divert anyway. The ops will be culled in the immediate wake of an accident but the effect is operationally incovenient, not itself a safety issue.
Last edited by FlightDetent; 20th Dec 2020 at 10:43.
How dangerous is a single runway, major airport?
Well I guess that was catastrophically demonstrated at Los Rodeos, Tenerife on a Sunday in March 1977.
Sunday was a busy day anyway at TCI (as Tenerife Norte Airport was known then) with many holiday jets coming in all day from all over Europe, Scandinavia, and the UK, often including many big jets 707's CV-990's, DC-8's, VC-10's and the new wide bodies 747, DC-10 and TriStar's.
TCI has a single runway operation 12/30 that had been lengthened to 3,000m, with ILS and a parallel Taxiway. No ground radar.
Throw in the mix on that day a terrorist incident on the nearby island of Gran Canaria meant that the Las Palmas Gando airport there was closed to all inbound traffic (again, Las Palmas is very busy on a Sunday) thus TCI saw many aircraft diversions coming to land there.
LPA ATC would not allow inbound aircraft to hold over the sea, even if they had enough fuel reserves (Of which Pan Am evidently had)
The consequences were was that TCI was soon swamped with very large jets parked up to a maximum on all of the available apron ramps, with the taxiway now also used for parking both the KLM and Pan Am 747 diversions.
KLM's passengers were disembarked into the Terminal but Pan Am's did not.
LPA soon re-opened and clearances were given to start clearing departures, and during this time the notorious foggy weather and low visibility started to close in over the airfield.
Pan Am was ready to go but did not have wing tip clearance to taxy safely past the KLM parked in front.
KLM reboarded, but 4 pax were lost in the terminal.
The KLM Captain then decided to tanker fuel to save time fuelling at LPA thus caused Pan Am more delays whilst KLM now waited for a fuel bowser.
The lost 4 pax (a family) were rounded up and were boarded on the KLM 747.
KLM was finally ready to go...But by now the weather was appalling, fog had quickly closed in, and the Tower could not now see the aircraft.
The controllers plan was for the 2nd 747 (Pan Am) to taxy down the runway behind the KLM and then exit it using one of the transverse taxiways which should clearly/ideally have been at exit C4, a 45 degree left turn, ideal for a 747. This would clear the runway for the KLM plane to take off.
Other aircraft were waiting on C1 and C2 to also join the runway and backtrack, after both 747's had departed.
One of the 747's Crews was completely unfamiliar with TCI airport, it's ATC and that 3 languages were being used.
Most of the rest of that Sunday afternoon is infamously ingrained to History, save to say that would we today allow in almost zero Vis & poor RVR two 747's full of passengers to both taxi down an active single runway together to backtrack the full length ?
Well I guess that was catastrophically demonstrated at Los Rodeos, Tenerife on a Sunday in March 1977.
Sunday was a busy day anyway at TCI (as Tenerife Norte Airport was known then) with many holiday jets coming in all day from all over Europe, Scandinavia, and the UK, often including many big jets 707's CV-990's, DC-8's, VC-10's and the new wide bodies 747, DC-10 and TriStar's.
TCI has a single runway operation 12/30 that had been lengthened to 3,000m, with ILS and a parallel Taxiway. No ground radar.
Throw in the mix on that day a terrorist incident on the nearby island of Gran Canaria meant that the Las Palmas Gando airport there was closed to all inbound traffic (again, Las Palmas is very busy on a Sunday) thus TCI saw many aircraft diversions coming to land there.
LPA ATC would not allow inbound aircraft to hold over the sea, even if they had enough fuel reserves (Of which Pan Am evidently had)
The consequences were was that TCI was soon swamped with very large jets parked up to a maximum on all of the available apron ramps, with the taxiway now also used for parking both the KLM and Pan Am 747 diversions.
KLM's passengers were disembarked into the Terminal but Pan Am's did not.
LPA soon re-opened and clearances were given to start clearing departures, and during this time the notorious foggy weather and low visibility started to close in over the airfield.
Pan Am was ready to go but did not have wing tip clearance to taxy safely past the KLM parked in front.
KLM reboarded, but 4 pax were lost in the terminal.
The KLM Captain then decided to tanker fuel to save time fuelling at LPA thus caused Pan Am more delays whilst KLM now waited for a fuel bowser.
The lost 4 pax (a family) were rounded up and were boarded on the KLM 747.
KLM was finally ready to go...But by now the weather was appalling, fog had quickly closed in, and the Tower could not now see the aircraft.
The controllers plan was for the 2nd 747 (Pan Am) to taxy down the runway behind the KLM and then exit it using one of the transverse taxiways which should clearly/ideally have been at exit C4, a 45 degree left turn, ideal for a 747. This would clear the runway for the KLM plane to take off.
Other aircraft were waiting on C1 and C2 to also join the runway and backtrack, after both 747's had departed.
One of the 747's Crews was completely unfamiliar with TCI airport, it's ATC and that 3 languages were being used.
Most of the rest of that Sunday afternoon is infamously ingrained to History, save to say that would we today allow in almost zero Vis & poor RVR two 747's full of passengers to both taxi down an active single runway together to backtrack the full length ?
This overlooks that both were departures, so on the segregated scenario discussed would both have been using the same runway anyway.
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rog747 - Another TCI problem was not having appropriate procedures and facilities/equipment in place to operate more than one aircraft at any one time safely in low visibility. The Milan/Linate runway collision in early 2000's involving the SAS MD87 and biz-jet crossing the runway again highlighted this where the biz-jet took a wrong turn, ATC couldn't see the aircraft, inadequate signs, lighting etc.
Regarding close parallel runways used in segregated mode, another capacity constraint is if an arriving aircraft on one runway needs to go around and one is departing on the other runway at the same time then there is an immediate risk of airborne conflict.
Regarding close parallel runways used in segregated mode, another capacity constraint is if an arriving aircraft on one runway needs to go around and one is departing on the other runway at the same time then there is an immediate risk of airborne conflict.
rog747 - I'm not sure that TCI would count as a 'major airport', except that night, when it was very unusually, and excessively, overcrowded.
The single runway was only one of several 'holes in the cheese' that resulted in the crash; a parallel runway wouldn't even necessarily have prevented an accident under those conditions - under which, as you say, the airport shouldn't even have been operating. Apart from the ones you've mentioned, an important 'hole in the cheese' was the impatience of the KLM captain who attempted takeoff in appalling visibility, such that he couldn't see a 747 backtracking towards him although he knew it was there, without making certain that it was clear of the runway (it wasn't, of course), and despite the attempt of the more experienced, but junior, flight engineer to warn him.
The single runway was only one of several 'holes in the cheese' that resulted in the crash; a parallel runway wouldn't even necessarily have prevented an accident under those conditions - under which, as you say, the airport shouldn't even have been operating. Apart from the ones you've mentioned, an important 'hole in the cheese' was the impatience of the KLM captain who attempted takeoff in appalling visibility, such that he couldn't see a 747 backtracking towards him although he knew it was there, without making certain that it was clear of the runway (it wasn't, of course), and despite the attempt of the more experienced, but junior, flight engineer to warn him.
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Thanks all for the comments. I'm delighted to receive so many.
In case your are interested - maybe some of you know Prague Airport - here is the back-story.
The planned new runway would be to the south of the terminal buildings whereas the current one is to the north, so as I understand it, there would be no need to cross one to reach the other. However the noise issue is that the new runway would bring the trajectory 1.5kms closer to the urban area. The Airport likes to claim that by closing 12/30 it will relieve noise for 200,000 residents but we discovered that in 2019 only 5% of flights used 12/30, whereas 50% of flights would use the new southern 6/24. They have just recently started playing the 'safety' card. One politician last week claimed that it was, in this respect "ordered by Brussels". I'll be on his case!
I am sure it's just a straight business issue, but without any evidence of need. They claimed the capacity would be reached based on growth figures by 2028, but they had no evidence of their own for where this growth was coming from, as I discovered by pressurising them under the Freedom of Info law - the Airport is State owned. I also discovered that Eurocontrol is open and helpful to members of the public who seek help understanding their data. Their forecasts, even pre Covid, didn't support the Airport's growth figures. It looks like a case of "build it, then we'll find some airlines to use it".
I'm a fairly regular flyer (how else would I get back to family and friends in London, especially when i got the call that my Mum had been given 24 hours to live? BA helped get me to her hospital bedside 6 hours after I got the call) and I appreciate Prague needs a good modern airport. But there are other airports in the country which lose money because they are underused, and in regions which need economic investment. And yes, I live in the zone where we would be disturbed by the new flights. But we bought the house in 2002 and as a Londoner of course I tried to do due diligence, with the airport so close, and we were told 'no plans to expand'. Grr.
Basically I supposed that if you guys are happy to fly in an out of Prague, or a similarly configured airport, then the "safety" rationale for a parallel runway is pretty low down the list, and you seem to generally confirm that. For which I, once again, thank you.
In case your are interested - maybe some of you know Prague Airport - here is the back-story.
The planned new runway would be to the south of the terminal buildings whereas the current one is to the north, so as I understand it, there would be no need to cross one to reach the other. However the noise issue is that the new runway would bring the trajectory 1.5kms closer to the urban area. The Airport likes to claim that by closing 12/30 it will relieve noise for 200,000 residents but we discovered that in 2019 only 5% of flights used 12/30, whereas 50% of flights would use the new southern 6/24. They have just recently started playing the 'safety' card. One politician last week claimed that it was, in this respect "ordered by Brussels". I'll be on his case!
I am sure it's just a straight business issue, but without any evidence of need. They claimed the capacity would be reached based on growth figures by 2028, but they had no evidence of their own for where this growth was coming from, as I discovered by pressurising them under the Freedom of Info law - the Airport is State owned. I also discovered that Eurocontrol is open and helpful to members of the public who seek help understanding their data. Their forecasts, even pre Covid, didn't support the Airport's growth figures. It looks like a case of "build it, then we'll find some airlines to use it".
I'm a fairly regular flyer (how else would I get back to family and friends in London, especially when i got the call that my Mum had been given 24 hours to live? BA helped get me to her hospital bedside 6 hours after I got the call) and I appreciate Prague needs a good modern airport. But there are other airports in the country which lose money because they are underused, and in regions which need economic investment. And yes, I live in the zone where we would be disturbed by the new flights. But we bought the house in 2002 and as a Londoner of course I tried to do due diligence, with the airport so close, and we were told 'no plans to expand'. Grr.
Basically I supposed that if you guys are happy to fly in an out of Prague, or a similarly configured airport, then the "safety" rationale for a parallel runway is pretty low down the list, and you seem to generally confirm that. For which I, once again, thank you.
Only half a speed-brake
It is always awkward when "safety" enters the discussion. Cutting to the chase, most of the time you can recognize a professional and truthful presentation of facts by the author's abstinence from the use of the S-word.
In a traditional case of damned if you do and exactly the same otherwise, any action's benefits have consequences on the negative side and weighing them against each other borderlines with the metaphysical. Sorting facts from chaff according to their relevance for any particular situation becomes impossible on purely technical grounds, without a "just cause" sense of direction.
In this respect, the only universal truth is that absolute safety can only be achieved once we simply stop flying. No airports, no machines, no humans.
As safety is of literal paramount importance what we use in the contemporary discourse (post-1985) is the terms "safety level" or "margin from error". That's the Columbus' egg: A change is to be reviewed relatively to what we already have, or against another possible choice. And this actually gives a good pivot point that even an informed outsider to the industry can use properly.
For your particular case:
1) For a given amount of movements at an airport, does a parallel dual runway configuration provide more room for error margins over
- a) a crossed double runway configuration
- b) a single runway configuration?
It is yes on both accounts. If you listed the genuine benefits of a parallel runway setup, the additional safety factor has a rightful place on it.
At the same time: If someone attempts to use "for better safety" call to justify building a secondary runway on top dubious capacity increase claims, they are destroying their credibility and blowing holes below own waterline.
In a traditional case of damned if you do and exactly the same otherwise, any action's benefits have consequences on the negative side and weighing them against each other borderlines with the metaphysical. Sorting facts from chaff according to their relevance for any particular situation becomes impossible on purely technical grounds, without a "just cause" sense of direction.
In this respect, the only universal truth is that absolute safety can only be achieved once we simply stop flying. No airports, no machines, no humans.
As safety is of literal paramount importance what we use in the contemporary discourse (post-1985) is the terms "safety level" or "margin from error". That's the Columbus' egg: A change is to be reviewed relatively to what we already have, or against another possible choice. And this actually gives a good pivot point that even an informed outsider to the industry can use properly.
For your particular case:
1) For a given amount of movements at an airport, does a parallel dual runway configuration provide more room for error margins over
- a) a crossed double runway configuration
- b) a single runway configuration?
It is yes on both accounts. If you listed the genuine benefits of a parallel runway setup, the additional safety factor has a rightful place on it.
At the same time: If someone attempts to use "for better safety" call to justify building a secondary runway on top dubious capacity increase claims, they are destroying their credibility and blowing holes below own waterline.
Last edited by FlightDetent; 21st Dec 2020 at 08:03.
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FlightDetent thanks, that's an excellent articulation of the necessary trade-offs, which I shall shamelessly steal.
In the case of Prague, the trade-offs would swing more easily behind "build it", if it were to the north of the existing one, since it would be further away from the city. That raises another point that maybe people can clarify. I have often heard it said that current practice is for new runways, or new airports to be located further away from the urban centres they serve, rather than nearer to them. Is that anything more than just a vague convention? (e.g. has anyone heard of "Brussels" seeking to enshrine it in a directive?). And if so is there a 'safety' element in that convention as well as environmental?.
As far as I know Prague Airport does not consider this because quite simply it does not own land to the north. I found that the northern perimeter fence is also the City boundary. That ought not to matter legislatively for a national asset, but planning law here is not fit for purpose. All kinds of transport infrastructure projects here are delayed interminably because the State cannot easily requisition land.
deltahotel thanks for list of single runway UK airports, very helpful. If anyone can think of similar configurations in North/West/Central Europe for an airport of similar importance, I'd be very grateful. Prague serves a city of 1.3m, has 2 public terminals, and is claiming a current passenger capacity of 21m. I'm not sure about aircraft movement capacities, but I'm only looking for general analogous airports which transport people would see as facing similar challenges.
Again, thanks so much, and I promise to clear off shortly
In the case of Prague, the trade-offs would swing more easily behind "build it", if it were to the north of the existing one, since it would be further away from the city. That raises another point that maybe people can clarify. I have often heard it said that current practice is for new runways, or new airports to be located further away from the urban centres they serve, rather than nearer to them. Is that anything more than just a vague convention? (e.g. has anyone heard of "Brussels" seeking to enshrine it in a directive?). And if so is there a 'safety' element in that convention as well as environmental?.
As far as I know Prague Airport does not consider this because quite simply it does not own land to the north. I found that the northern perimeter fence is also the City boundary. That ought not to matter legislatively for a national asset, but planning law here is not fit for purpose. All kinds of transport infrastructure projects here are delayed interminably because the State cannot easily requisition land.
deltahotel thanks for list of single runway UK airports, very helpful. If anyone can think of similar configurations in North/West/Central Europe for an airport of similar importance, I'd be very grateful. Prague serves a city of 1.3m, has 2 public terminals, and is claiming a current passenger capacity of 21m. I'm not sure about aircraft movement capacities, but I'm only looking for general analogous airports which transport people would see as facing similar challenges.
Again, thanks so much, and I promise to clear off shortly
Only half a speed-brake
As a citizen and national of the region, I openly declare being insulted by putting PRG and LTN in the same basket.
It is besides the point anyway, because reducing PRG to single runway is not on the cards. As it should not, along with its peers of VIE, BUD, WAW, BER perhaps also OTP, BEG and ATH if you will.
It is besides the point anyway, because reducing PRG to single runway is not on the cards. As it should not, along with its peers of VIE, BUD, WAW, BER perhaps also OTP, BEG and ATH if you will.
Last edited by FlightDetent; 21st Dec 2020 at 09:32.
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Just looking at last night’s destinations comes up with 10+ single rwy airports. Not all huge it is true, but serving big cities GVA BSL SOF. others OPO BLL VNO NTE ORB AOI RIX SKP.
Flight Detent is right - PRG has a long way to go to compete with LTN as a destination!
Also true is (can be) the effect of losing one of the rwys. A few years ago the ac ahead of me on approach declared a Mayday, engine failure, continuing to land. We went around and asked for the other rwy and were told that due fire services involved on the S rwy that the airfield was closed.
Flight Detent is right - PRG has a long way to go to compete with LTN as a destination!
Also true is (can be) the effect of losing one of the rwys. A few years ago the ac ahead of me on approach declared a Mayday, engine failure, continuing to land. We went around and asked for the other rwy and were told that due fire services involved on the S rwy that the airfield was closed.
Only half a speed-brake
GVA and SOF on your list would count, the others come nowhere close comparable.
2019 data for PRG show
- 10x weekly mainland China (direct to 4 different cities)
- 14x weekly DXB, half T7 half A380
- 7x weekly ICN A380/T7/B747
- 15x daily Russian Federation.
Still a petty regional airport viewed from the seat of the empire but markedly different than the other listed ones. Now comparing Est�dio do Drag�o with anything in PRG, that's a different sport altogether!
Last edited by FlightDetent; 21st Dec 2020 at 10:32. Reason: grammar, grammar and still no luck
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I just looked up the passenger numbers for Stansted and Luton. I was staggered to find that in 2019, Stansted, with a single runway, processed 28m passengers.
Prague in the same year managed 17.6m. Luton beat that too, albeit "only" by 1m. From the list of European airports mentioned above, Geneva is already handling slightly more than Prague and there is no talk there of the need for a 2nd runway.
Obviously there are passengers and then there are flight movements, but when I see the Stansted figure, and then the Prague Airport mgmt. bleating that they will hit *capacity* of 21m by 2028, and there won't be any more slots...well I'm just a SLF specimen, but something there doesn't seem quite right. Am I not entitled to say to Prague: "should try harder with the runways you have"?.
I would admittedly prefer to be flying to and from Prague rather than Stansted or the hell-hole that is Luton, but that's about the terminals. And nobody has any problem with Prague investing further in the terminals, which is also part of the plan.
Prague in the same year managed 17.6m. Luton beat that too, albeit "only" by 1m. From the list of European airports mentioned above, Geneva is already handling slightly more than Prague and there is no talk there of the need for a 2nd runway.
Obviously there are passengers and then there are flight movements, but when I see the Stansted figure, and then the Prague Airport mgmt. bleating that they will hit *capacity* of 21m by 2028, and there won't be any more slots...well I'm just a SLF specimen, but something there doesn't seem quite right. Am I not entitled to say to Prague: "should try harder with the runways you have"?.
I would admittedly prefer to be flying to and from Prague rather than Stansted or the hell-hole that is Luton, but that's about the terminals. And nobody has any problem with Prague investing further in the terminals, which is also part of the plan.