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Almost all of the major airports in the United Kingdom are single-runway (or functionally-single-runway) installations, with only two of the very busiest (Heathrow and Manchester) having as many as two runways (although Heathrow has a third under construction).

(In addition, even for the three major UK airports that have two runways, the two runways are always a parallel set, with no provision made for crosswind operations.)

This is - with few exceptions - far fewer runways than would be normal for airports of their size. Taking the seven airports in the UK with more than ten megaemplanements in 2018 and comparing them to similarly-sized airports elsewhere:

  • Heathrow (two runways, with a third under construction) v. O'Hare (seven runways, with an eighth under construction)
  • Gatwick (two [functionally one] runways) v. Newark (three runways)
  • Manchester (two runways) v. la Guardia (okay, two runways)
  • Stansted (one runway) v. Baltimore-Washington (two air carrier runways1)
  • Luton (one runway) v. Calgary (four runways)
  • Edinburgh (one runway) v. Norman Mineta (two runways)
  • Birmingham (one runway) v. Raleigh-Durham (two air carrier runways1)

Having so few runways not only increases congestion and severely limits the number of flights that can use the airport without infringing on safe separation distances between aircraft, but also poses the risk, for the four single-runway airports,2 of an unserviceable runway (for instance, due to snowplows, potholes, trespassers, flocks of birds, wayward deer, or a disabled aircraft) shutting down the entire airport, potentially for a prolonged period of time.

Why do the UK's major airports have so few runways compared to the norms for airports of their sizes?

1: Plus one general-aviation runway each for Baltimore-Washington and Raleigh-Durham.

2: And, to a lesser degree, for functionally-single-runway Gatwick, as its emergency backup runway is close enough to the main runway for a single debris event to potentially affect both.

Vikki
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    For one thing, the USA is roughly 35 times larger than the UK. Texas alone is more than twice the size of the UK. When it comes to land use, the "norm" in the US isn't necessarily comparable to other countries, especially much smaller ones. – Pondlife Nov 04 '19 at 05:12
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    @Pondlife: I am aware that, due to the US's far greater size, a far greater proportion of people choose to fly (rather than drive or take a train) in the US versus in the UK. That's why I compensated for that by specifically matching the busiest UK airports to other airports with very similar traffic levels. – Vikki Nov 04 '19 at 05:20
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    I think Pondlife is referring to land use rather than average travel distance. Land value in the UK is more than double that in the US. – Sanchises Nov 04 '19 at 06:50
  • @Sanchises: Oh. Good point. – Vikki Nov 04 '19 at 06:58
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    Heathrow has a third under construction - not yet it doesn't. And if certain politicians get their way, there never will be. Should it go ahead, you'll note that it is (you guessed it) another east/west runway. – Jamiec Nov 04 '19 at 08:00
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    Possibly worth noting that in WWII a number of airbases were constructed in the UK with a 3-runway configuration, see e.g. en.wikipedia.org/wiki/Class_A_airfield – Bob says reinstate Monica Nov 04 '19 at 14:53
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    @Bob, and many GA fields still have non-parallel runways, but airliner take-off and landing speeds are probably double that of WWII and GA aircraft, so they are less affected by side-winds. – Robin Bennett Nov 04 '19 at 14:59
  • @Sean are all those runways in use at the same time though? Or they they pick the one or two that are most usable in current weather conditions? – stripybadger Nov 04 '19 at 16:10
  • @stripybadger: Well, for the first comparison on the list, Heathrow has two parallel runways (soon to be three), whereas O'Hare has five parallels (soon to be six). – Vikki Nov 05 '19 at 03:00
  • Potentially historical - smaller runways were harder to target with bombs in WW2 and its simply stayed that way ? – Criggie Nov 05 '19 at 03:28
  • If you divide the area of the UK by the total number of runways that serve international flights you will find that it actually has proportionally more runways than the US. That is: the average service area of UK runways is smaller than for US runways. – blues Nov 05 '19 at 08:14
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    @Sean, you are talking "the norm for airports of these sizes", yet all the examples you give are the USA (and one in Canada). Is there any reason that the "norm" couldn't be either or neither of these countries' models (especially given that the USA is the 3rd most populated country in the world, they likely don't represent any worldwide norm in their sizing needs)? –  Nov 05 '19 at 08:21
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    An interesting look at the history of London's airports can be found here - https://www.youtube.com/watch?v=AbAal7jIWQ4. Not really a direct answer to your question, but an interesting insight nontheless. – Vitani Nov 05 '19 at 12:17
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    @Pondlife While that's absolutely true, even Schiphol (AMS) has 5 runways (6 if you include the non-international one). That's in the Netherlands in an area where land is just as much at a premium as around the large UK cities. – Mast Nov 05 '19 at 19:56
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    @Criggie not really, during the Blitz most RAF fighter command airfields were just that, fields. There were no marked runways, aircraft would take off in whatever direction was most convenient from a flat area of grass. – jwenting Nov 07 '19 at 10:52

4 Answers4

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There are perhaps 101 non aviation-related reasons why the UK does not have larger airports, such as space consideration (we're only a small island!), politics (NIMBY!), civil engineering (Airports are commonly near urban centres and are often surrounded).

However, the most aviation-related related reason I can think is that we just simply rarely need cross runways. If you look at most large airports in the UK their runway(s) are east-west(ish). The reason for this is over 70% of the prevailing wind direction in the UK is West or SouthWest.

In addition, we rarely have extremes of wind - those exceeding the crosswind capabilities of common commercial airliners. Heavy snow is even rarer. I can probably count the number of times a runway at a large airport has been closed due to any of the reasons you mention in the last 20 years on two hands.

Bottom line; it's just not necessary. There is no socio/political/weather climate to warrant it.

Jamiec
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    Amsterdam shares has much the same climate as London has, yet Schiphol Airport has 6 runways. – Koyovis Nov 04 '19 at 09:27
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    @Koyovis I assume Amsterdam has much more variance in the wind direction. They usually use the 3 North-South runways (or 2 of them and 06/24), so winds are probably not "West or SouthWest" most of the time. – Bianfable Nov 04 '19 at 09:31
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    @Koyovis, look at the graph for dominant wind direction for AMS: https://www.windfinder.com/windstatistics/amsterdam-schiphol there is a lot of variation in wind direction and some runways are used to allow for flight paths that cause less noise polition for the surrounding citizens – Brilsmurfffje Nov 04 '19 at 09:36
  • @Brilsmurfffje Indeed, my point as well. I wonder how different the wind direction scatter at Heathrow is. – Koyovis Nov 04 '19 at 09:39
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    @Koyovis, LHR is a lot more consistent as can be seen from the graph: https://www.windfinder.com/windstatistics/london-heathrow this is also logical given the close proximity of AMS to the ocean – Brilsmurfffje Nov 04 '19 at 10:01
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    OTOH old UK airports used the triangle style runways (also Heatrhow, you may still see on areal photo the old runways), so wind was a factor. -- Amsterdam has only one large airport, London has 4 (to 6). Italy seems to use the same method: an additional airport, instead of increasing the size of the larger one. I think local authorities has much more weight (let's get new job, but also: we have enough departures). – Giacomo Catenazzi Nov 04 '19 at 10:56
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    The North Atlantic Oscillation ensures that westerly winds predominate over most of Great Britain. A non-aviation consequence of this is that in most British cities, the West End is the posh district. This came from the days of coal fires, when the windward west-side had the cleaner air. Eastenders had to choke in the smog. – Oscar Bravo Nov 04 '19 at 13:36
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    @Koyovis The climate is "much the same", but the devil is in the detail. For example Schiphol has an average of 26 snowy days per year. LHR has an average of 4. – alephzero Nov 04 '19 at 17:08
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    @OscarBravo oh, that explains the name of that TV show with the awful theme song that always made me dive for the remote after the news was over – llama Nov 04 '19 at 18:35
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    @OscarBravo Thank you! I've been wondering about that ever since I lived in Sheffield, years ago, and noticed the pattern. – owjburnham Nov 04 '19 at 21:25
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    @Koyovis Also, that might tie in with the land value point. When the Netherlands is short on land they just make more. – owjburnham Nov 04 '19 at 21:26
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    Possibly airports in places like the US have more GA / small airline traffic. Major UK airports discourage GA (and small airlines - it's fairly impossible to get a scheduled flight between most UK cities), Airliners are happy with a single/paired runway, so that's what gets built, with taxiways and terminals where cross runways would go. – Rich Nov 05 '19 at 01:17
  • @Brilsmurfffje: Going by that wind rose, it seems like Heathrow should have its runways oriented northeast-southwest, rather than east-west. – Vikki Nov 05 '19 at 02:56
  • @Sean - I think it did, originally. https://en.wikipedia.org/wiki/History_of_Heathrow_Airport#cite_note-18 – Dave Gremlin Nov 05 '19 at 10:37
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    @OscarBravo Huh, I never realised that about the West Ends. Nice! – Lightness Races in Orbit Nov 05 '19 at 14:31
  • @owjburnham: The same goes for pretty much any coastal airport (look at Logan, Kansai, Hong Kong...). – Vikki Nov 06 '19 at 01:50
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    @Sean And, of course, the proposed Thames Estuary Airport! – owjburnham Nov 06 '19 at 12:00
  • @Rich While the U.S. does indeed have more GA traffic, most major U.S. airports tend to discourage it as well. Major U.S. airports do have far more aircraft movements than almost anywhere else in the world (last I looked pre-Covid, 8 of the top 10 by movements were in the U.S.,) but they're still mostly just passenger jets at the major airports. Just a whole lot of passenger jets. ATL and ORD both had around double the aircraft movements of LHR before Covid, for example, virtually all of which was scheduled airline flights. ATL and ORD each have 5 parallel runways. – reirab Oct 11 '21 at 10:50
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It's ALL about land use.

Look at Mirabel, Denver's new airport, or Dulles (at the time it was built). They basically razed some farmland. America had the opportunity to do a whole lot of that.

Whereas in the UK, you have an ancient civilization dotted with villages, the entire system of landed [owns land] gentry (as seen on Downton Abbey; Highclere Castle has been in the same family for 300 years), and the social systems involved the land itself: the land was owned by the lords (literally "land lords"), and leased to the occupants; that's where for instance Mr. Darcy's "income exceeding ten thousand per year" came from.

And the House of Lords is still a political force.

In the UK, airport sites aren't selected, so much as gouged out of history.

So it is not lightly that they expand an airport.

Personally, I think in this kind of situation, the entire exercise is folly; they should site airports on land that could not possibly have been developed except with modern methods, such as the proposal to put London's airport in the Thames estuary. Oh wait, there's history there too.

Harper - Reinstate Monica
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    I've downvoted this because it uses fictional sources as references and ignores the fact that many, many airfields have been built in the UK (especially England) for military use and have since become civilian airports (and brownfield sites) – Dave Gremlin Nov 04 '19 at 17:43
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    @DaveGremlin It's rather harsh to downvote for that. The reason for fictional sources is this is what the reading public can relate to. Why shouldn't we use readily available social metaphor to describe how things worked? Answers should be accessible. If you want to downvote me for that, you should be prepared to show how the concepts can be gotten across non-fictionally. Please write your own answer and we will let the readers decide. As far as the former military use, military exigencies can get a military airport established, but that does not help build or expand a civil one. – Harper - Reinstate Monica Nov 04 '19 at 18:16
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    Also you do realize Highclere Castle is real? So is the world of nobles and gentry portrayed in the Jane Austen books. She didn't invent the English class system. – Harper - Reinstate Monica Nov 04 '19 at 18:19
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    I'm not sure why the wreck of the Richard Montgomery is brought up specifically in opposition to the idea of a Thames Estuary airport; it's going to go boom sooner or later, airport or no, and better to have it happen now and get it over with than wait until the surrounding area is even more built-up and crammed with people and development than it is now. – Vikki Nov 05 '19 at 03:22
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    Why @Sean, I do believe you have the plot of a James Bond movie there! Evil genius aims to blow up the Montgomery so we can get on with building the airport, which he profits from somehow... – Harper - Reinstate Monica Nov 05 '19 at 07:40
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    @Harper Are you saying that I can only criticise points in your answer if I provide one of my own? Whenever I read a bad novel do I have to rewrite it to be allowed to criticise it? – Dave Gremlin Nov 05 '19 at 10:24
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    +1 for "gouged out of history.". An excellent description of pretty much any non-trivial civil engineering project anywhere in the UK. – DrMcCleod Nov 05 '19 at 13:15
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    Heathrow: 4.74 sq mi. O'Hare: 11.9 sq mi. - you're going to need a bigger plot. Also, there's no comparison to be made to the city that once had both the largest and busiest airports at the same time. – Mazura Nov 06 '19 at 04:58
  • Sorry but this is basically a bunch of stereotypes. The House of Lords is now almost completely non-hereditary. It's hard to see how Jane Austen is relevant, given that she died most of a century before the first powered flight. And, really, it doesn't much matter who owns the land or how long they've owned it. Demolishing a section of London to expand Heathrow really isn't much different from demolishing a section of Queens to expand JFK. – David Richerby Nov 06 '19 at 21:06
  • @DavidRicherby: Except that you don't need to demolish any sections of Queens to expand JFK, since it's right next to Jamaica Bay and you can just make new land to expand the airport onto. – Vikki Nov 07 '19 at 22:55
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When Heathrow was opened as a commercial site it had THREE different runways in a triangle and by 1955 it had SIX runways - You can see them here: Wikipedia commons - arranged to allow parallel operation on any 2 runways no matter what the wind direction was.

But with the coming of larger transport aircraft having higher landing speeds and greater crosswind tolerances, the need for the extra runways was diminished - and by the end of the 1950s only the east/west runways were being used - they got extended into the 2 runways in use today, whilst the other runways were closed - they're used as taxiways today.

Heathrow is adding a third runway - east/west for capacity.

Most other airports are single runway or "functionally single runway" - which means that only one runway is ever in use at a time because that's all they need to be, or because that's what they've been limited to by planning restrictions.

Gatwick is in the middle of trying to open up its second runway for parallel operations - this was part of the original plan when it was opened, but is being fought hard by locals on noise grounds.

In other areas one of the ways to quell opposition has been for airports to quietly buy up land under the approach paths for 15-20 miles in each direction and ensure it stays as farmland.

This is not economically possible in the UK - and even if a brand new airport was to be opened away from a major city and rail/road links magicked into place for it (which have proven very hard to get established - even a decent north/south rail link into Heathrow is near-impossible), the odds of being able to acquire affected land at any price are slim to negligable.

Federico
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Stoat
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    +1 It's very difficult to get planning consent for new runways, it takes years to go through the process, the appeals, public enquiries, judicial reviews etc. Also, Doncaster airport (the former RAF Finningley) is a great example of the point you make in the last paragraph - big airport with little traffic – Dave Gremlin Nov 06 '19 at 10:05
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    Buying land even THREE miles west of Heathrow is going to be tricky. Some of the land there last changed hands just short of a thousand years ago - and William the Bastard's current successor is not going to sell Windsor Castle now. – Martin Bonner supports Monica Nov 06 '19 at 10:29
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The wind in the UK is fairly constant east-west, thus there is no need to construct runways in other directions. The only reason to construct extra runways, is for the case where the capacity of the current runway system is insufficient. LHR shows that you can handle a large number of yearly flights with just two runways. LHR is currently operating at max capacity, thus there are plans for a third runway. The other airports you are mentioning are not even seeing half the traffic of LHR and are thus fine with using just one runway.

If you are currently running an operation with just one runway, your capacity can more than double if you construct another runway, since you can then use one for take-off and one for landing.

LHR has some graphs indicating how the wind influences the operation: https://www.heathrow.com/noise/heathrow-operations/wind-direction

Airports closer to the ocean, such as Aberdeen, have more runways since the wind direction is less constant.

TLDR; dominant wind direction dictates the orientation of the runways and the number of yearly flights dictate the number of runways. This is all within political/environmental/spatial limits.

Toby Speight
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Brilsmurfffje
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    LHR does use easterly operations sometimes. It's 20 years since I worked there, but the switch between westerly and easterly operations uses up pretty much all of the slack in their scheduling. This means the fact that the wind doesn't change direction often is crucial to operations – Chris H Nov 04 '19 at 14:09
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    "The wind in the UK is fairly constant east-west" needs to be corrected. The wind in the UK is usually a south westerly, not east to west. However it can be from any direction. I'm not sure what you mean by 'constant' in this context, neither the wind speed nor the direction have much constancy about them. – Dave Gremlin Nov 04 '19 at 17:38
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    @DaveGremlin "East-west" here refers to both east to west and west to east (as in 09/27) as opposed to, say, 02/20. – PerlDuck Nov 04 '19 at 18:06
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    Adding a third parallel runway usually only gives a marginal increase in capacity, because you need traffic patterns for arrival, departure and missed approach for each, which is why middle runways are rather seldom in the world. – Simon Richter Nov 04 '19 at 18:57
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    Aberdeen has the one runway and three helipads - it's basically a huge heliport (for the oil industry) with some fixed wing facilities, – Rich Nov 05 '19 at 01:20
  • @PerlDuck - Even using that interpretation, 'east-west' is still incorrect. – Dave Gremlin Nov 05 '19 at 10:20