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How dangerous is a single runway, major airport?

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How dangerous is a single runway, major airport?

Old 21st Dec 2020, 11:14
  #41 (permalink)  

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Originally Posted by deltahotel View Post
Flight Detent is right - PRG has a long way to go to compete with LTN as a destination!
Depends if the bike stand in front of Perfect Chicken, East India Dock Road, E14 0ED is part of the destination Luton experience. But that is not appropriate to this thread.

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 Estádio do Dragăo with anything in PRG, that's a different sport altogether!

Last edited by FlightDetent; 21st Dec 2020 at 11:32. Reason: grammar, grammar and still no luck
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Old 21st Dec 2020, 15:26
  #42 (permalink)  
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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.
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Old 21st Dec 2020, 15:47
  #43 (permalink)  
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When I was involved in assessing runway capacity and safety back in the 1990s, Gatwick was the most efficient runway in Europe in terms of both safety and capacity at a time when the parallel taxiway was not being used as a second (backup?) runway. And it appears from this link it still is:-

There are also a number of single runways on remote ocean isands - Bermuda and Seychelles spring to mind. They were operated safely as far as I remember. Single runways are definitely not inherently dangerous.
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Old 21st Dec 2020, 17:44
  #44 (permalink)  

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Happy thread with people keen on facts. So shall we endure...

The Prague airport re-construction of 1960-1963 that overlapped the original triangular, British-military-like runway configuration and enlarged its area to the north significantly already planned for a parallel set of 24R/L. Only the northern one (present 24/06) outside the contemporary boundaries had been built, as the construction of the southern one would had shut down the whole airport for about 2 years, intersecting the original triangle in half, and the need for it was not foreseen for some decades then.

The Prague City Master Urban Planning document entered the southern parallel runway - the faulty PR for which is this thread's topic - in 1972. In a sense, the OP is very correct that no new plans for airport development were brewing in 2002, as what had been signed and sealed 30 years before his purchasing time is sufficient even today.

Incidentally, when building new runways in Europe, a quarter of century timeframe is par for the course. Cue the development history of F.J. Strauss Airport (MUC) opening in 1992 having been approved by the Bavarian government in 1969.

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Old 22nd Dec 2020, 15:46
  #45 (permalink)  
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So in that spirit of seeking facts - or at least opinions of professionals in the field - I have some more questions on the subject.

a) Given that I've just discovered Stansted turns 28m passengers now on a single runway, is it too simplistic to suggest publicly that if Stansted can manage that, then Prague can certainly manage 21m on a main runway plus a reserve? What are the other possible variables when comparing the movement capacity of the two airports?
b) to whom is that question aimed? or rather, who might accidently take it as a criticism? I am wondering if the ATC organisation would be the ones that stipulate how many movements the Airport can schedule in, so they might be the ones who feel they are being unfairly compared with Stansted. Which then leads to the question, which authority regulates how many movements Stansted can safely handle?

2. Different question. Prague's prevailing wind is overwhelmingly westerly, and usually, to someone used to London, benign. So they use 6/24 90% plus times. But they switch to 12/30 when the winds make a rare shift. So what happens if they replace 12/30 with a parallel 6/24?. What if there is a nasty northerly? Do you pilots then just have to cope with the crosswinds? How big a deal is that, in flying terms? (this question applies to all single runway airports I guess)
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Old 22nd Dec 2020, 16:07
  #46 (permalink)  
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No comment on Q1.

2. If there’s a nasty Northerly then yes, we would! Modern ac have pretty chunky crosswind limits (my 757 is 40kts) and it’s a challenge but trained for. To exceed that would be rare. Be based in Birmingham (BHX) 15/33 and crosswind landings become the norm.
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Old 22nd Dec 2020, 20:00
  #47 (permalink)  
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Q1 - Stansted's 28m passengers (pre-COVID) are based mainly on medium sized aircraft such as B737-800 movements with high load factors and scheduling 50 movements per hour at peak times. Gatwick on the other hand had over 40m passengers (pre-COVID) with a single runway with up o 55 movements per hour at certain peak times. A mixture of wide-bodied and medium size aircraft and also two passenger terminals.

To achieve this runway capacity and passenger throughput there are a number of considerations:
- Have rapid exit turn-offs (RETs) angled and located at the correct distance from the runway landing threshold for the majority of aircraft types likely to use the runway
therefore minimising runway occupancy time.
- Have sufficient taxiways, including runway holding areas to sequence departures and parking stands infrastructure to match the runway capacity otherwise delays will
- Have a passenger terminal building or more than one terminal to achieve the passenger throughput.
- Have airspace design so ATC delays for departing and arriving aircraft are minimised.
- Another factor with number of movements is environmental and night noise restrictions (normally 2330 to 0600hrs local time in UK) where for example London Heathrow,
Gatwick and Stansted airports have different quotas for each season with Heathrow being the lowest and Gatwick having the highest number.

21m is easily doable on a single runway provided the above issues are considered.
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Old 22nd Dec 2020, 20:25
  #48 (permalink)  
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Good thread - an interesting read!

Re 1, i'd suggest there are thousands of variables that would keep airport planners up at night, but some that immediately spring to mind;
  • ability to get to/from the runway quickly - that would include minimising dead time on the runway before turning off at an intersection and also the ability to get to it quickly/efficiently. For the latter, think of a junction on a major road - if that junction cant cope with the amount of traffic coming at it, it wont be able to efficient shove traffic onto the motorway, even though the motorway might have stacks of capacity remaining. Having rapid exit taxiways, for example, in just the right spots for the major aircraft types will speed things up hugely.
  • aircraft handling - or in effect everything from getting off the runway to getting back on the runway, including all of the aircraft servicing. I don't know the short/long haul split, and how that compares to, say, Stansted, but any myriad of reasons from employment contracts to facilities to x or y or z could impact the ability to turn aircraft around quickly
  • number of stands - are there enough, incl. of the right type?
  • weather - Gatwick operates more or less flat out every day throughout the year with no real weather issues. Does Prague suffer (at all) when its snowy? I'm not saying it falls over completely, but if everything takes a couple of minutes longer that amounts to a substantial reduction in capacity
  • seasonality - UK airports are fairly busy all year round, particularly in London. Is Prague the same?
  • Planning restrictions - 21m might be on the basis of noise etc. agreed many years ago. It could be argued (Heathrow do) that having another runway allows that noise impact to be spread out so could be a reason to explore it?
  • Resilience - i think this is common in the US. FLL for example managed to get a new runway because delays on its existing runway were causing (evidenced) knock on delays across the entire USA, despite only having half the number of passengers of, say, Gatwick. (as an aside, wouldn't it be good if the EU managed airspace/airports across Europe and could use this argument to expand airports this side of the pond, so the 'knock on delays' argument might actually have some legs - maybe Heathrow might happen in a reasonable timescale then!)
There are bound to be more. All of which is to say that it wont be easy to compare two different airports.

As a further thought, talking about passengers may be a bit of a misnomer. Perhaps you could consider ATMs. Do they have dedicated cargo flights, for example? or perhaps they are full to busting in terms of number of aircraft they can land/service a day, but they are all tiddlers (i.e. the passengers per aircraft figure is very low). Having a second runway could allow a diversification of destinations, e.g. allowing more long haul into the mix on bigger aircraft.

To go off on a bit of tangent, a similar debate can be had re active traffic management, e.g. controlling the flow of traffic to maximise capacity/throughput - the principle used on Smart Motorways, for example. This video is useful;

The reason i raise that is this - if you leave a road as it is, with ever increasing traffic, safety begins to be an issue, normally commencing with nose-to-tail collisions. Increasing capacity, whether through technology to better manage the flow or through building extra infrastructure, allows that traffic to flow better, and safety improves (to a point).
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Old 22nd Dec 2020, 21:28
  #49 (permalink)  
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LessThanSte - Some good points

Regarding weather, it's interesting how it can vary so much at the London airports on a winters day, particularly fog and snow. From my experience Heathrow being west of London tends to get less snow than Gatwick and Stansted with Stansted more likely getting snowfall being over 300ft elevation and it's further east location influenced by north/north east cold winds bringing showers inland from the North Sea.

Gatwick is situated in a valley with a river running nearby so perfect for lower temperature overnight and formation of fog yet at the same time Heathrow and Stansted are clear with higher temperatures. Although Stansted does suffer from fog occasionally in winter in certain weather patterns due to it's rural location and elevation and often Gatwick and Heathrow are clear at the same time.

Another issue with single runway is an alternate in case of diversion. For example if one of Heathrow's runways experienced an unplanned closure the alternate is the other runway but with a single runway airport the alternate would be to another airport, provided of course the ground handling and parking capacity at the alternate is available. I believe with single runway airports aircraft may uplift more fuel at the origin so in the event of a diversion they have sufficient fuel for the alternate airport.

Another issue with the very busy London airports, which includes Luton, if there is an unplanned closure of any of these airports runways then a situation quickly develops where many aircraft are looking to divert at very short notice to other airports and in the space of a few minutes this can cause significant increase in ATC workload. Also some of these airports may not be able to accept these diversions for reasons already mentioned.

Altogether a very interesting and complex subject
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Old 23rd Dec 2020, 10:46
  #50 (permalink)  
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My perception (which I'd love to examine with data) is that Prague really is a quite benign airport, both re capacity and weather, compared with say Stansted

- when thinking about the runway issue, it suddenly occurred to me that I could not remember the last time I was stacked coming into Prague, whereas coming into LHR it's a red-letter day if I am not. Is that a reasonable indicator of real capacity issues? (and would I be able to request data to underpin it?)
-there is not even that much snow any more (rather sadly) last significant falls were I think 2011 or 2012. I was stuck for three days that year before heading back to London for Xmas, but the problem was snow at LHR not here. Prague has all the gear. No brooms...
- winds as a I said, usually benign. Nary a bump, and i notice these things.
- It is badly located for fog, and it took years after the fall of the communists to get Cat 3 autoland (correct?) . But now that isn't an issue, and indeed the fog itself seems less common, it might have been pollution - fuelled in the past.

I'm very open to getting reality checks on my perceptions - it's why I am here - but so far I come away from this thread even more convinced that at least technically, the parallel runway is a solution searching for a problem.
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Old 23rd Dec 2020, 12:29
  #51 (permalink)  
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Looking at Musket post, fully agree with paras 1,2,4.

Don’t think using a second rwy at destination as an alternate stacks up. If 27L at LHR is out due weather then so will 27R and at the planning stage the weather requirements for alternate are more stringent than for destination.

That said we are allowed to do it but the weather has to be pretty good (2000’+, vis 5k+) but I can’t remember it in the last 20 years.


ps. Who doesn’t love Cat3 ops?!
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Old 23rd Dec 2020, 18:59
  #52 (permalink)  
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deltahotel - What I meant by unplanned runway closure was an aircraft emergency/disabled aircraft or perhaps runway surface breakout. It would be extremely unusual for both 27L and R to be out due fog. All LHR runways are CAT III equipped in respect of ILS and lighting, however the IRVR (instrumented runway visual range) for each runway can differ greatly so ATC would likely adjust the landing and departure runway to suit. The downside with fog is runway capacity is reduced due to the need to increase the arrival spacing on approach so ILS signal integrity is not affected. The reduced landing rate figures based on the IRVR value are published in the UK AIP. This results in ATC flow control measures which can result in flight cancellations, mainly short haul, particularly flights where there is more than one daily frequency to/from a particular destination.
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Old 23rd Dec 2020, 19:17
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Sure. Maybe I misunderstood - my point just that even with a two rwy destination we would still carry fuel for a different alternate.
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Old 23rd Dec 2020, 19:50
  #54 (permalink)  
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Had a situation at Heathrow back in the early noughties, when I was waiting for a BA flight to Paris mid afternoon.
A KLM 767 blocked 09R with a wheel bearing failure and a few minutes later a Virgin aircraft taking off from 09L blew a tyre and closed that runway. I don't how many diversions there were but the T4 departure screen suddenly went to all flights cancelled.
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Old 26th Dec 2020, 10:14
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One of the problems is single runway airports without parallel taxiways so aircraft have to taxi down the active runway - LTN & LCY come to mind but there must be many other examples.

Going off topic another major issue the configuration in which runways are operated. La Guardia for example is interesting with take offs and landings on intersecting runways allowing around 70 movements per hour, but this works ok and there are plenty of examples particularly in the US. The most complex I have seen is SFO which combines two sets of intersecting close parallel runways - two almost simultaneous take offs in one direction followed by two not simultaneous but closely spaced landing (presumably a heavy must follow a lighter aircraft rather than the reverse). This allows up to 90 movements per hour including a number of heavies which works ok in good visibility but I have seen delays due to "bad weather" in conditions that wouldn't raise an eyebrow at airports like Heathrow.

Taxiing aircraft having to cross active runways is always an issue (ATL, LAX, etc). ATL is interesting in that it is the only example I can think of of a "grade separated" taxiway. (If you haven't seen it aircraft taxi past the end of the runway and an aircraft that is landing off or landing could be directly overhead.)

Last edited by Peter47; 26th Dec 2020 at 10:29.
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Old 26th Dec 2020, 11:30
  #56 (permalink)  
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One of the problems is single runway airports without parallel taxiways so aircraft have to taxi down the active runway - LTN & LCY come to mind but there must be many other examples.
Before parental bankruptcy forced my employer's closure three years ago, my civil and structural engineering colleagues were working on a further major upgrade to facilities at London City, including decking over the dock to carry a full length taxiway. This work was successfully handed on to another consultancy to complete (think my some of my colleagues transferred too) and looking at Google maps, the decking is being constructed so presumably it won't be too long before the taxiway is in use.
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Old 26th Dec 2020, 18:52
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Peter47 - In Luton's case whilst the parallel taxiway doesn't extend to the runway ends most departures which are not performance limited can accept the reduced distance when departing from an intersection so avoiding a backtrack of the runway to the full length. I believe in USA airports like SFO use the automated "runway status lights" system (red lights) which hopefully mitigates runway conflict issues. There's a video on YouTube about Paris CDG runways status lights which may be the only European airport to provide them.
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Old 26th Dec 2020, 20:44
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Originally Posted by Peter47 View Post
Taxiing aircraft having to cross active runways is always an issue (ATL, LAX, etc). ATL is interesting in that it is the only example I can think of of a "grade separated" taxiway. (If you haven't seen it aircraft taxi past the end of the runway and an aircraft that is landing off or landing could be directly overhead.)
I suspect you are referring to "End-Around" taxiways (grade-separated means one passing over/under the other). ATL is one of a dozen or so US airports with EATs, and there are a number in Europe including AMS, BCN, FRA and MXP.

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