Which London Airport Should Get an Extra Runway?

Officially, Gatwick has only one runway. The more sharp-eyed of you might wonder that concrete structure is immediately to the right of its “official” runway….

London has needed at least one more airport runway for years, if not decades, most visibly/obviously at Heathrow, but lesserly so at the other airports ringed around London too.

I’ve never been sure if Britain’s sorry saga of self-inflicted economic harm, in the form of limiting the passenger capacity of Heathrow airport and adding greatly to the tax cost of flying in/out/through all its airports, both ostensibly in the name of “saving the planet”, should be viewed as tragedy or comedy.

It is tragic because the net “planet saving” achieved is as close to zero as one can get – plenty of airports in Europe and elsewhere are eager to take over from Britain and become the major hub for traffic in and out of Europe.  This might perhaps now be a greater consideration than before, due to Britain leaving the EU, making the loss of air service and revenue a more stark national win/lose outcome than before.

It is comedic not only for its futility but for its pacing – plans to add more runways at Heathrow date all the way back to 1947 when the first runway at what was then a new airport (Heathrow opened to the public on 31 May 1946) was already being supplemented by the construction of two more runways, with another three more runways planned to follow, for a total of six runways.  To put that in perspective, O’Hare in the US has seven runways, Amsterdam has six, and both Frankfurt and Paris (CDG) have four.

The two extra runways being built in 1947 became just one runway plus a taxi-way, and the three additional runways were never built, leaving Heathrow unhappily frozen in size with only two runways.

Back in 1946 it would have been relatively easy to build more runways because Heathrow was located in a low-density area, more or less countryside, compared to the heavily built-up area it has become in the 75 years since then (with of course, much of that density being the result of the airport).  Heathrow has wanted a third runway (and ideally a fourth and so on runway too – but these days it dares not to even hint at such concepts) pretty much for its entire life, but struggles on with just two runways handling way more flights every day than was once thought possible.  That is why flights are so often delayed, and why “slots” (approvals to operate flights in/out of Heathrow) are so expensive.

After extensive planning, submissions, and reviews, Heathrow was granted permission by the government in 2009 to construct a third runway.  You might think that to be the end of the story, but rather than the end, it was nothing more than perhaps the end of the beginning.  Since that time, the government has changed its mind several times, and the occasional approvals for a third runway have been greeted by protests and legal maneuvering to delay or prevent the runway being constructed.

In December 2020, Britain’s Supreme Court dismissed the latest appeal (against the airport expansion, ie allowing the runway to proceed) but that doesn’t mean the bulldozers started work the next day.  Oh no.  It just frees the airport to now start an entire new submission/request for approval to the government for a third runway.  Yes, back to square one.

Further underscoring the glacial pace of “progress”, ten months later, as of mid September 2021, the airport has yet to re-submit.  You’d have thought, if they really wanted another runway, they’d have had most of a submission already prepared, awaiting the Supreme Court decision, and could have finished it off and sent it in within a couple more months.

A cynic might wonder whether Heathrow’s owners really want another runway at all or if they just want to maintain a “spoiler” role, stopping the one runway that the government might be willing to pass out, from being awarded to any of the other airports.  This is not an impossible notion, especially when one considers the costs involved.  The official cost of the third runway has been stated as being £14 billion, and unofficially estimated at £38 billion, and of course, that was then, and what the new cost will be when the new submission is filed and whenever work actually gets underway is anyone’s guess, but £50 billion (about US$70 billion) seems far from unlikely.

So, in 2021, 12 years after the runway was “approved”, and whatever the reason, Heathrow finds itself no closer and maybe even further away from being able to “break ground” and start a third runway development than it was in 2009.

Alternatives to Heathrow’s Expansion

In addition to the greenies trying to save the planet, the third runway is running afoul of another issue as well – the UK government wants to de-concentrate the current cluster of airport services around London and give better service to Britain’s regions.  This is part of their broader policy of boosting regional development; on the one hand it makes sense and is a vote winner for the regions that stand to benefit; but on the other hand, it is an operational challenge.  Britain – and England in particular – is so small that it makes little sense to have multiple major international airports, all within a couple of hours traveling time of each other.  But it would further “harm the planet” by requiring people to first take a short connecting flight to a major hub before flying on from the hub.

The plan to boost regional airports is understandable, but it will only create originating and destination traffic for each region.  It won’t benefit from any hubbing, because there won’t be the rich selection of convenient connecting flights to other parts of Britain/Europe/beyond such as can only be offered at a reasonably sized hub.  This weakens the traffic airlines can expect from regional airports, which in turn means fewer flights, which then means less appeal to travelers, less revenue for the airport, and so on, and generally creates no-win situations for the airlines, the airports, and the would-be passengers.

None of these issues seem to have been adequately considered in the UK government’s plans to boost regional airports.

As an alternative, the government might do its bit to appease the greenies by only allowing Heathrow to grow if there is a matching reduction in flights from regional airports.  That would seem to be the exact opposite of its primary policy of boosting regional airport traffic, but let’s not let logic (or creating the best national infrastructure) interfere with the concept of winning the most possible votes.

Suffice it to say, the battle for another runway at Heathrow is far from over, and the necessary government approval for the next time an application is submitted – never very reliable or constant – remains uncertain.

The entire process is also comedic in the sense (if that is the right word) of some of the alternate propositions being offered, instead of growing Heathrow’s capacity.  Britain’s Prime Minister, Boris Johnson, was very keen, when he was Mayor of London (2008 – 2016), to create an entirely new airport in the Thames Estuary to the east of London.  This would probably not be in addition to Heathrow, but instead would replace Heathrow, which would then be closed.

The kindest thing to say about that concept is that the land cost would have been low.  But the development cost would have been high, as would the related costs of then “connecting” it by road and rail to London, and the “below the line” related costs of all the infrastructure suppliers needing to relocate.  Thankfully, now he is Prime Minister, he seems to no longer be as keen on that concept.

London’s airports, clockwise from the top, are Stansted, London City, Gatwick, Heathrow and Luton.

But Heathrow is far from London’s only airport.  It is just one of five major airports in London, and others not all that much further out of the city are also eager to be considered as London airports too.  Some of the other four airports would like an extra runway, too – currently three of the other four have only one runway, and Gatwick sort of has a sort-of second runway.  Stansted, currently with one runway, applied for permission to add a second in 2008, with the application being withdrawn in 2010.  It is unlikely that London City Airport could add another runway.

Luton has been growing its traffic, and plans to grow still further, but has not actually come out and said it wants a second runway.  It hints at it, and is certainly planning to make its one runway as productive as possible by increasing taxiways to it, but has not dared actually come out and directly ask for another runway.

In 2015 an official Airports Commission concluded that Britain needed to add an extra runway to one of its London area airports (something that had been obvious to everyone else in the world for years if not decades), and recommended it be given to either Heathrow or Gatwick, and then eventually nominated Heathrow as being the better choice.

Gatwick Wants Another Runway – And Already Sort of Has It, Awaiting Official Blessing

Gatwick, notable for being the busiest single-runway airport in the world, is eager to get another runway.

It was constrained from doing so because of a 40 year agreement it had with the local council (the West Sussex County Council) not to expand, running from 1979 through to 2019.  But now that 2019 has passed, Gatwick has apparently not only decided to toss its hat in the ring and ask for government permission for another runway, but has secured the support of the local and regional councils to do so.

Gatwick has the benefit of sort of having a second runway already, which it has not counted as a second runway as per its agreement with the local council, and has refrained from using it concurrently with the current runway in a manner that would cause it to be obviously an operating second runway, not least because the two runways are slightly too close together at present, preventing both runways from being in use simultaneously.

In September 2021, it announced plans to modify its second “northern” runway, shifting it 40 ft to one side (from the present 656 ft separation to 696 ft separation) to improve the separation between it and the other “main” runway up to a point where it meets official distance requirements.

It is a shorter runway (8,415 ft long, compared to 10,879 ft on the main runway), so would not be able to handle all the same planes as its existing runway, although it is relevant to note that this shorter runway is still considerably longer than Luton’s single runway (7,087 ft).  It seems it would be possible to lengthen the runway, as you can see from the picture at the top – there is some room at the “bottom” of the runway (as seen in the picture) but there isn’t any mention of that yet – clearly Gatwick is trying to make its proposal as easy to approve as possible.

The 40 ft shift is laughably trivial compared to adding another runway to Heathrow.  Sure, other changes would be needed as well, but this is a very easy solution.  To put it in context, the runway is almost 150 ft wide, so it needs to be shifted by merely a quarter of its width – have a look at the picture above, and then imaging shifting the runway by one quarter of its width.  That’s almost a nothing movement, isn’t it.

This and other related improvements would increase the airport’s passenger handling capacity up to 75 million passengers a year.  Its present level of around 46 million passengers a year is already exceeding its current designed capacity.

What is Best for Britain?

Should Britain have one super-airport or several slightly smaller airports?  Airports definitely benefit from economies of scale, which is why Heathrow has always dominated the London airport scene so thoroughly.  In 2018, Heathrow had 480,339 flights and 80.1 million passengers.  The second largest London airport, Gatwick, had 283,926 flights and 46.1 million passengers.  Heathrow is close to twice the size of Gatwick.

Relieving the pressure on Heathrow (and Gatwick) by adding capacity at other airports in the country is only moderately effective, because it doesn’t address the needs of people flying in/out/through London, which is where the main capacity crunch exists.

Allowing Heathrow to grow even larger would give even more potential connections and flight times, both for people flying in and out of Heathrow and for people connecting through and changing planes in Heathrow.  That would help Heathrow (and therefore Britain) to maintain its European primacy in the face of threats from Paris/CDG, Amsterdam and Frankfurt, and less obviously from smaller airports but with growth potential in Europe, and also with other hubs in further away places.  For example, a passenger in a secondary city in the US, seeking to fly to a secondary city in Europe, can choose either to fly to a US hub and then directly from there, or to a European hub, and then directly from there.  So, while seemingly counter-intuitive, major US hubs such as ATL, ORD and JFK are also competing with Heathrow, as are regional hubs such as Hong Kong, Singapore, even Bangkok.

Growing Gatwick instead of Heathrow helps relieve the pressure on flights to service the London (and secondarily, England in general) market alone.  If you’re simply flying from somewhere to London, you shouldn’t really mind too much if you go to LHR or LGW, other than from considerations about the “last mile” travel between the airport and your ultimate destination in London or elsewhere in England; the Heathrow Express is a slightly faster way to get into reasonably central London than the Gatwick Express, but what is 15 minutes on a journey that probably (including all delays and stages) took you perhaps 15 hours (from North America)?

However, to frame this in “either/or” terms is ignoring a third alternative, and I don’t just mean considering the other three airports – Stansted, Luton, and London City.  The third alternative is to more closely couple Heathrow and Gatwick airports, to create a virtual single airport.

Currently, the two airports are about 25 miles apart, as the crow flies.  As the car or bus drives, however, they are 33 – 40 miles apart, with the longer distance (taking the M25 motorway) actually giving the faster travel time (if you’re lucky, 40 minutes; but during the day, more like an unpredictable hour, and often much longer).  By train, well, forget about that.  There are no easy ways to travel by train – you’d need to travel in to London by one train, then across London by another train or taxi, then from another rail station, on to the other airport.  Slow, complicated, and very inconvenient if you have much luggage or are traveling during rush hours.

There have been proposals mooted for direct fast train service to connect the two airports.  With trains at up to 180 mph, on a new line designated “HS4Air“, this could shrink the travel time down to possibly as little as 15 minutes.  The rail line would actually run 87 miles, starting at the Ashford stop on the HS1 (Eurostar) line most of the way from London to the Channel Tunnel, and then going to Gatwick, Heathrow, and a little way further north to connect with the under-construction new HS2 line that goes from London north.  The concept was very quickly rejected when proposed in 2018 (probably due to the government feeling over-extended on the current HS2 development), but could be revived at any time.

Especially if the link is “air-side” – ie, on the departure/arrival gate side of security – the 15 minutes, which of course is predictable and unvarying during the day, rather than dependent on traffic – effectively joins the two airports together, making it nothing more than a slightly longer time to get from one gate in one terminal to another gate in another terminal.

Noting the massively lower cost of modifying Gatwick’s second runway compared to buying the land and building an entire new runway at Heathrow, it would seem the same money would more than pay for both the Gatwick runway modifications plus a high speed rail connection, even if only for the 35 or so miles between the two airports, and the net result would be a super-airport unlike anywhere else in the world.

The resulting airport – sometimes jokingly described as “Heathwick” – would be convincingly larger than any other airport in the world.  Using 2019 numbers, we see airport rankings

RankAirportAnnual Passengers (2019 – millions)
1Heathrow & Gatwick127.5
3Beijing Capital100.0
4Los Angeles Intl88.1
5Dubai Intl86.4

Heathrow already scores as the “most connected” airport in the world in terms of the number of destinations served, and the added flights and destinations currently served by Gatwick would reinforce the combined airport’s primacy by that measure, too.

Obscured in those numbers is the added growth potential by adding an extra runway, at either airport, and with the location of the added runway no longer quite so critical, the lower cost location (almost certainly Gatwick) could be chosen.  The new combined operation could handle over 155 million passengers a year.

This would not primarily encourage more Brits to fly, because for originating and arriving passengers, the airport choice isn’t as important.  It would instead encourage more international travelers to use London as a hub, and of course, some of those passengers transferring from one flight to another will choose to stop-over enroute, bringing tourism benefits to London and England and Britain as a whole.

All five London airports primarily serve international markets.  The busiest five routes are to Dublin, Amsterdam, New York, Dubai and Madrid.  The most recent statistics I can find show in 2011 there were 30 international routes to/from London with over 1 million passengers a year, but only three within the UK.

With good rail service within Britain, and with 85% of the population of the UK being in England, travel distances between major population centers are too short to justify flying (for example, the second largest city in England is Birmingham, an easy 108 mile/under 2 hour drive from Heathrow).  It is unfortunate that Heathrow in particular, and lesserly Gatwick, are not well integrated into the national rail system, and giving both airports better connections to the main rail lines would allow more people to make more of a journey by rail and less of the journey by car or air.

Conbining the two airport locations would also give the combined airport an improvement in bad-weather or emergency response.  It is possible that weather challenges at one airport might not be so severe at the other airport, or at least, one location could be given a robust set of snow-clearing equipment to ensure it can always stay open.

If a crash or other disruption closed down a runway or terminal or entire airport, at least some of those flights could divert to the other part of the Heathrow-Gatwick combined airport.  Yes, that can happen at present, too, but if it does, there are problems transferring passengers to the other airport if they need to collect their car, or make a connection, whereas, with the two airports joined together, it becomes trivial, easy, and quick.

There would be one amusing reversal needed, in combining the two airports.  Until 2009, one company owned both airports (and others too).  The company was required to sell Gatwick to avoid it having a monopolistic position in the London airport market; combining the two airports would need ownership to also be amalgamated, and give the combined airport owner great market power again.


London’s five airports, between them, clearly need at least one more runway.  In truth, all five airports would probably each like another runway (or even two more), but it is unlikely the government will generously allow airports to have the runways they want, due to national and political considerations and the strong anti-airport movement in the country.

With perhaps only one runway “up for grabs”, the two contenders are either Heathrow or Gatwick.  Heathrow has historically been the favored solution, but Gatwick has a “stealth” second runway that could be made into an official “real” second runway relatively quickly and at relatively low cost and matchingly low impact, unlike the very high costs and impacts that all the land acquisitions and development costs would have at Heathrow.

As part of allowing Gatwick to activate its second runway, it would make good sense to amalgamate the two airports into one super-airport, with high-speed rail service providing an easy 15 minute connection between the two airports.  This would allow for further benefits of scale and reinforce London’s role as the crossroads of the world.


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