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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.

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    $\begingroup$ 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. $\endgroup$ – Pondlife Nov 4 at 5:12
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    $\begingroup$ @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. $\endgroup$ – Sean Nov 4 at 5:20
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    $\begingroup$ 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. $\endgroup$ – Sanchises Nov 4 at 6:50
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    $\begingroup$ 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. $\endgroup$ – Jamiec Nov 4 at 8:00
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    $\begingroup$ 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 $\endgroup$ – Bob says reinstate Monica Nov 4 at 14:53
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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.

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    $\begingroup$ +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 $\endgroup$ – Dave Gremlin Nov 6 at 10:05
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    $\begingroup$ 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. $\endgroup$ – Martin Bonner supports Monica Nov 6 at 10:29
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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.

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    $\begingroup$ @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. $\endgroup$ – Bianfable Nov 4 at 9:31
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    $\begingroup$ @Koyovis, look at the graph for dominant wind direction for AMS: 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 $\endgroup$ – Brilsmurfffje Nov 4 at 9:36
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    $\begingroup$ @Koyovis, LHR is a lot more consistent as can be seen from the graph: windfinder.com/windstatistics/london-heathrow this is also logical given the close proximity of AMS to the ocean $\endgroup$ – Brilsmurfffje Nov 4 at 10:01
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    $\begingroup$ 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. $\endgroup$ – Oscar Bravo Nov 4 at 13:36
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    $\begingroup$ @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 $\endgroup$ – llama Nov 4 at 18:35
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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.

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    $\begingroup$ 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) $\endgroup$ – Dave Gremlin Nov 4 at 17:43
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    $\begingroup$ @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. $\endgroup$ – Harper - Reinstate Monica Nov 4 at 18:16
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    $\begingroup$ 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. $\endgroup$ – Harper - Reinstate Monica Nov 4 at 18:19
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    $\begingroup$ 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... $\endgroup$ – Harper - Reinstate Monica Nov 5 at 7:40
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    $\begingroup$ +1 for "gouged out of history.". An excellent description of pretty much any non-trivial civil engineering project anywhere in the UK. $\endgroup$ – DrMcCleod Nov 5 at 13:15
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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.

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    $\begingroup$ 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 $\endgroup$ – Chris H Nov 4 at 14:09
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    $\begingroup$ "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. $\endgroup$ – Dave Gremlin Nov 4 at 17:38
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    $\begingroup$ @DaveGremlin "East-west" here refers to both east to west and west to east (as in 09/27) as opposed to, say, 02/20. $\endgroup$ – PerlDuck Nov 4 at 18:06
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    $\begingroup$ 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. $\endgroup$ – Simon Richter Nov 4 at 18:57
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    $\begingroup$ Aberdeen has the one runway and three helipads - it's basically a huge heliport (for the oil industry) with some fixed wing facilities, $\endgroup$ – Rich Nov 5 at 1:20

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