Will London Heathrow airport ever get a third runway? Does London Heathrow airport actually need a third runway? If it did get a third runway, would that be enough - or will Gatwick or Stansted need more tarmac, too? Or, how about really solving the London airports capacity problem with an all-new four- or five-runway hub airport out east in the Thames estuary? Clearly, London needs that - or maybe not? Is there even a London airports capacity problem?

While this debate rolls on - and it has been rolling for at least 30 years, through two major review studies and, now, a third timetabled to report late in 2015 - airlines jostle for slots, flights stack up in bad weather, passengers grumble, business people moan about not having direct flights to everywhere, Heathrow area residents despair that there might actually be more flights and more noise and politicians dip in and out of the fray, usually with no reward but a bloody nose.

Some comfort may be taken from the fact that, in 2013, the issue is being debated with some urgency. That was in evidence at the recent Royal Aeronautical Society in London, where the Westminster Energy, Environment and Transport Forum hosted a packed house to hear heavy hitters from all sides - politicians, airlines, airports, environmentalists - take a "fresh look at UK airport capacity" and ask: it is time for a third runway at Heathrow?

However, anyone who expected to walk back outside with an answer to that question must have been disappointed; on this issue, it is entirely reasonable to be absolutely convinced by the last person to make their case - and then, on reflection, to be uncertain.

Heathrow airport chief executive Colin Matthews opened proceedings by - hardly surprisingly - making the case for Heathrow as the pre-eminent London airport. Noise and air quality, he argues, are not major issues (poor air quality being more a product of diesel road vehicles in and around the airport than aircraft emissions) and the airport is well-connected by rail to London. Airlines like to fly long-haul services from Heathrow, he says, because they make more money there, partly owing to access to transfer passengers. As for calls to better open the market to competition from other London airports, he adds, bring it on - though Heathrow's real competition are the Continental hubs at Amsterdam, Paris and Frankfurt.

London airports traffic 
Note: London City Airport figures: 2.0m in 2005 growing to 2.9m in 2011

Game, set and match to Heathrow, then? Not exactly. As Matthews readily concedes, there are significant economic and environmental costs to "every option".

Environmental costs, indeed. HACAN ClearSkies chair John Stewart - whose group represents the interests of the 275,000 people who live under Heathrow flight paths and the 150,000 who will join them if a third runway is built, is understandably opposed to making Heathrow any bigger. "That number [425,000] should be decisive. It is very, very difficult to argue in the face of those numbers that Heathrow should be expanded."

Moreover, he argues, while the "noise impact should rule out the third runway", air quality is also a show-stopper. Dismissing Matthews' casual dismissal of the issue, Stewart notes that with 480,000 flights at Heathrow yearly today, many local areas exceed European air pollution limits - so growth to 700,000 or so sounds like a legal non-starter.

Then, there's climate change. Stewart was not the only speaker to observe that the UK can meet its aviation CO₂ emissions reduction targets and expand Heathrow - but only by freezing or even cutting traffic at all other UK airports.

Again not alone, Stewart also koshed the notion that Heathrow capacity constraints are holding back the UK economy by restricting flight transfers - because for an astonishing 93% of passengers, Heathrow is origin or destination. Any connectivity crisis, he argues, can be met by shifting short-haul flights to other London airports.

As for so-called mixed-mode operations, which would increase Heathrow capacity by having aircraft take off and land from the same runway, Stewart reckons 80,000 flights yearly could be added. But, he forecast: "If mixed mode took place there would be a revolution in [wealthy West London district] Richmond."

So, in Stewart's assessment runway three cannot happen for environmental reasons, is not needed for economic reasons and will not happen for political reasons.

Which sounds like the end of the story until one hears from Tim Yeo MP. Yeo - who should know, being chair of the British Parliament's energy and climate change select committee - sees no particular issue with expanding aviation and meeting the UK's CO₂ commitments. Meanwhile, he says, passengers arriving at a London airport from Hong Kong must think they've come to the "third world". Something needs to be done, Yeo argues, and London needs a proper hub airport. Heathrow, he adds, is where expansion can happen most quickly and most cheaply.

Or, maybe not. London Gatwick chief executive Stewart Wingate is adamant there is no capacity crisis, and certainly no connectivity crisis. Heathrow may be full, he says, but Gatwick, Stansted and Luton all have capacity to spare: "We just need to use it more effectively." Ultimately, Wingate believes that effective use will see second runways at Gatwick and Stansted.

But as for worries that London-bound passengers are entering some third world darkness, Wingate notes that one-runway, two-terminal Gatwick has, since it was sold in 2009 to break Heathrow owner BAA's monopoly of London airports, invested heavily in facilities and has another £1.1 billion lined up to spend in 2014-2020.

London airports snapshot: 2011

Passengers

Aircraft movements

Heathrow 69.4m 481,000
Gatwick 33.7m 251,000
Stansted 18.0m 148,000
Luton 9.5m 98,000
City 3.0m 69,000
Southend .04m 25,000

Source: UK CAA

Just to complicate the decision matrix, Gatwick's notion that private sector investment and competition will resolve London's air traffic problems was a perfect set-up for the next speaker: Birmingham airport chief executive Paul Kehoe.

Underscoring the complexity of the issue, Kehoe essentially suggests a redefinition of the term "London". If planners would "listen to the consumer" rather than to airlines, politicians and airport chief executives, says Kehoe, it would be crystal-clear that the prospect for making greater use of his Birmingham airport is being ignored. Passengers, he argues, clearly like to fly to Amsterdam to change aircraft but barriers to competition ranging from the UK's steep air passenger duty to bilateral deals are preventing Birmingham from fulfilling the same role. By breaking open bilateral deals and offering an air passenger duty holiday for start-up routes, Birmingham airport "could be a London airport".

Those like Kehoe who urge caution before breaking ground on new airport development will have heard just what they want to hear from Cait Hewitt. The deputy director of the Aviation Environment Federation dismisses the "myth" of London's airport capacity crisis, noting that official traffic forecasts have been falling - the half-million flights demand mark has been pushed back into the 2050s long grass - while "aviation's value to the economy is considerably overstated". Moreover, says Hewitt, connectivity is a business issue, but does not have to be from a hub, or point-to-point and in any case the proportion of air travel for business has been falling.

Daniel Moylan did not then stand up to start his presentation with the phrase, "Oh, please" - but he might have done. Moylan is London mayor Boris Johnson's aviation advisor, and Johnson is the number-one advocate for building an all-new super-hub east of London in the Thames Estuary. Moylan dismisses investment in Heathrow as "trying to squeeze a quart into a pint pot" and in any case a stopgap at best - what's needed is four runways, not just three, and the "scale of the environmental catastrophe" already imposed on west London by two-runway Heathrow makes expansion "impossible".

Starting from scratch to the east, though, would positively transform an area blighted by unemployment and poor connectivity to London and the rest of the UK. As for recent estimates that the scheme would cost the UK taxpayer £30-35 billion, Moylan observes that for a 15-year project, £2 billion a year or so is "doable", and no adequate option is much cheaper than any other. The mayor, he added, would also consider turning Stansted into a modern hub, a project that would also help transform east London.

In any case, he stresses a third runway at Heathrow "is a chimera - we're really talking about a fourth runway". And, he adds, when places ranging from Dallas and Atlanta to Paris and Hong Kong have concluded that they need a single, coherent hub it is just possible that they are right; London notions of "knitting together" several airports with transport links to make a "virtual hub" don't sound viable in the face of such modern examples.

Which really did shut the book - until Robin Cooper took the podium. The director of regeneration, community and culture at Medway council, which oversees the Estuary region, dismisses various plans for siting a new, 12 million passengers a month airport, suggesting that planners do not appreciate the scale of the disruption they are proposing. Bulldozing nine villages housing 23,000 people and importing the 100,000 workers supporting Heathrow is bad enough, before considering the estimated £75 rail fare from central London to the new hub.

Moreover, hub plans assume that Heathrow will close - but, wondered Cooper, which government thinks it has the authority to tell privately owned Heathrow to close?

Hence, Cooper puts his weight behind those calling for better use of existing capacity - including east London's Southend airport: "Support regional airports. They have a part to play."

Ultimately, the debate was well summed up by by Flightglobal Ascend chief economist Peter Morris. First, he says, learn from others; remember, for example, Montreal Mirabel international airport. Opened in 1979 56km from the city, it was at the time the world's biggest airport - and it closed 20 years later, unloved by passengers and airlines.

Second, by all means keep the scheme feasible. UK aviation has been largely privatised: "There is no 'public money' so the plan must work for the stakeholders - investors, operators and users."

Third, do bear in mind that "we start from here". Nobody today would build a major airport on the southwest side of London, with prevailing southwest winds - but that's what London has, and there is an enormous amount of physical and human capital tied up in it.

Fourth, there will be no agreement without recognising that on many issues the parties must agree to differ; policy should be based on evidence, but some people will always rate, say, noise issues while others look at economic benefits.

And critically, said Morris: "There is a real problem here". For decades, inefficiency has been layered in to schedules for passengers and airlines. There is cost to that, perhaps £1 billion a year.

Morris, like other speakers, calls for cross-party consensus. But as there has been no consensus for a generation or more it may be wishful thinking to expect the Davies review to provide a clarity that unites the various interest groups passionately attached to the "third runway" issue.

Source: Air Transport Intelligence news