There is no possibility of a third Heathrow runway being built without controversy.

Against the boons identified in the report from Sir Howard Davies and the Airports Commission, there are serious questions. Contrary to the impression sometimes given, the latter are not the preserve of people living and working in the south-east of England.

One detail often overlooked in the argument over Scotland's referendum was the issue of transport, specifically of air transport. The uncomfortable fact was that, even with independence, the country would have relied on the Heathrow hub for its links to the world. These links have been bad enough for long enough, a source of complaints for which no remedy has been provided. The idea that a third runway could make matters worse for Scottish travellers is therefore worrying.

The commission is clear about this. If demand for landing slots for lucrative long-haul flights trumps the claims of domestic services, Scotland will see its share, one that has been diminishing for years, shrink further. Yet if Heathrow is locked in competition with overseas hubs - already a fact of industry life - the pressure to restrict Scottish services will intensify.

It is, in one sense, an argument between local and international. All of the world's great airports are in competition for customers and capacity. The claims being made by Sir Howard on Heathrow's behalf rest, in large part, on the fact. According to his commission, a £17 billion investment could aid "the UK economy" to the tune of £147bn. It could create 70,000 jobs by 2050. But what should we say if Scotland's connections to the world are restricted as a result?

We can already guess the chief beneficiary of a third runway. Even as it worries over air quality, noise pollution and the bulldozing of almost 800 homes, London would take the lion's share of the spoils. In one view of the United Kingdom, that might seem inevitable, even fitting. The idea that a hub for an entire country might leave a significant "region" at a disadvantage is, on the other hand, impossible to justify. Heathrow would be failing in its advertised purpose.

The proposal to create a start-up fund to support new routes, like the demand for a cut in landing charges for passengers using UK routes, is fine and well. It surely would not hurt. The commission's belief that the Government might be able to circumvent European competition rules and use "public service obligations" to guarantee slots for domestic services is, on the other hand, creative. No one knows whether such a scheme would be countenanced.

If it failed, hopes for the "economic and social development" of the entire UK thanks to Heathrow would be forlorn. That problem, when it arises, will not be resolved with rhetoric, whether Unionist or Nationalist. The benefits of union would come into question if barriers were raised to travel and Scottish trade, especially if they were raised because Scotland's interests were not in Heathrow's commercial interest. But in the matter of hubs and links, no purely Scottish alternative exists, none is envisaged, and none is thought feasible.

As David Cameron's government gingerly accepts the Airports Commission report, it should remind itself that Heathrow is supposed to be an asset for all the UK. No other view is acceptable.