The business lobby wants it. The government wants it. The mayor, Boris Johnson, is just gagging for it. Anyone who is anyone seems determined that London needs a "hub" airport.
And, following this morning’s news that the UK government’s Airports Commission had rejected Johnson’s proposals for a new airport in the Thames Estuary, it seems increasingly likely that one of London's existing airports will be it. This has delighted the big two, and the bosses of both Heathrow ("the only hub left in the race") and Gatwick ("Britain's choice is now clear") are now going around busily explaining why they are the only serious candidate left in the race.
It's clear what these guys get out of it: airports are also businesses, and business want to grow. Why the government or business should be so keen, and what exactly the rest of London gets out of it, perhaps takes some more explaining.
What is a hub?
Let’s start with the science part. "Hub and spoke" is a way of modelling a network in which most journeys go via a few central points. Here's an example:
Image: Elwood64151, via Wikimedia Commons.
There are 15 different airports there. To link them all directly, through “point-to-point” flights, you'd need (quick bit of maths) 120 different routes. But relatively few people want to fly from, say, Albuquerque to Salt Lake City: it’s just not worth an airline’s while to frequently fly the route.
So, instead, a couple of the airports, in this case Denver and LA, are designated “hubs”, which have a disproportionate number of flights routed to them. The outlying airports, which have relatively few, are the “spokes”.
At first glance, this looks like it might be annoying if you happen to be the guy who wants to fly from Albuquerque to Salt Lake City. Actually, though, it might be better even for him. The greater efficiency of the network makes it profitable for the airline to run more frequent planes: the guy might have to change in Denver, but at least he won’t have to wait several days and pay a fortune to make the trip.
Real aviation networks are a bit more complicated than this, of course. And while individual airlines may designate their own, personal hub (Emirates has Dubai, Lufthansa has Frankfurt, etc.), there's no universal definition of the term. It basically just means "big airport with a lot of direct flights". This is the status that Heathrow is determined to maintain.
What are the benefits?
It's obvious why an airport wants to be a hub. It's pretty clear why a hub/spoke model would benefit an airline, too: the greater efficiency makes it possible to replace large numbers of half-empty routes with fewer, fuller ones.
What's more, any airport with spare capacity will be less subject to delays (it’s easier to catch up after problems); and one with large numbers of scheduled flights can offer a wider variety of connections. On the whole, then, a big hub should work better than a small one.
And if you’re not in the aviation industry...?
There are basically three reasons to want to be in the catchment area of a major international hub airport.
1) More destinations. Hub airports, by definition, have more flights to more places. That's good for holiday makers, and good for London's large international population. But it should also be good for...
2) The economy (domestic). London is a major centre for finance, media and several other multinational industries: the more places you can easily get to from London, the more likely companies in those industries are to think it worth setting up shop here. Air freight is also a thing, so this doesn't just apply to services either. There's also...
3) The economy (transient). Any thriving airport is a source of GDP in itself. Even if passengers or freight are only travelling through London, rather than getting off and walking around, that's money that comes into the country that would otherwise be going to Amsterdam or Paris. In other words, the better our air connections, the richer London should be.
So, whether you're a business traveller, or are holidaying on an obscure Pacific island, or just like living in a country with some sort of economy, the hub airport works for you. So we should all be cheering it on, right? Hmm.
What are the downsides?
The arguments in favour of hubs, alas, are not as clear as the aviation industry would like us to think. Many connecting flights are now going via places like Dubai and Doha, which are less out of the way than northwestern Europe: it’s not clear if this will mean a reduction in demand in London and other nearby cities, but it might. New planes such as the Boeing 787 or the Airbus A350 can also do long-haul flights with relatively small number of passengers, making it profitable to fly more point-to-point routes. That could undermine the entire hub/spoke model anyway.
Perhaps most damagingly, some studies suggest that simply increasing the range of destinations on offer doesn’t boost growth at all. What really matters is the number of passengers who actually arrive and leave: being a stopping point for the transient may not benefit the local economy at all.
That’s a problem, because any major airport development will have a pretty nasty downside: noise, air pollution, traffic congestion, all of which will be borne overwhelmingly by those on the flight path or near the airport itself.
This is why decisions about aviation capacity are so incredibly hard. The benefits are widely shared between us; the costs are concentrated among a few. Those few will get angry, and those few can vote.
If you want an explanation for why the Airport Commission won't be releasing its final report until after next year's election, this is it.