More runways = more runways.
More planes = more planes. End of story.
Potential capacity is only that, POTENTIAL. If people don't fly in the numbers required, economics will limit the flights. Big stadia don't pull big crouds, it is what happens in them that does.
At least there will be less fuel burned on taxi and waiting for a take-off slot, and less burned while stacking to land.
We lament about extra lanes on the motorways, but we sloth along in the middle one and waste the extra one, cause jams, and waste so much fuel daily in unnecessary congestion that it makes aeroplanes jealous.

Ian, Gosport,

it is an inevitable phenomenon that is to happen in the future.people are more and more in need of the convenient and time-saving transportation while train and long-distance coach maybe die down gradually.what becomes more blank is ground.on the contrary, the sky is to be more congested with aircrafts even other vehicles to be invented in the coming days

samuel lv, Suzhou, China

It is crazy to build a third runway at Heathrow - not only is it totally out of sync with our general obligation to protect the environment, but the noise and pollution levels would be unbearable for millions of people. A new airport should be built in the Thames estuary with flights coming in over the sea. The total number of flights should be strictly capped and flights out of Heathrow / Stansted / Gatwick / Luton / City airports should be reduced. Build a proper high speed link from the new Thames estuary airport to London and on up to Birmingham, Manchester and through to Scotland.

Sam, London,

with another runway - would this not enable more planes to land sooner rather than have them circling waiting for a slot?

Gary Clayton, Wimbledon,

I love my country fervently(England)but wish we had more of a "can do" approach like the U.S.If we did there would be a fine new airport out in the Thames estuary by now.(Hong Kong has the knack,too!)

HD, WsM,

Maybe if the government actually had some foresight & invested in a highspeed rail network at affordable rather than rip off prices like many European countries we could at a stroke free up airspace that is made up of all those pointless domestic flights.

A Quinn, london,

When they were proposing terminal 5 at Heathrow they said no third runway. Now they're talking about a third runway and (it seems) a sixth terminal)

This is sheer madness. Do our politicians think that we have no memory, and that we don't see them as hypocrites. No wonder trust in Labour is so low at the moment

Rob, Birmingham, UK

Scottish PM now Head of UK Clearances. Take this idea back home Gordon.

Noise is terrible
Pollution a real health hazard
Danger from crash unacceptable
Ecconomic ruin as more money leaves UK than comes in
NO ONE has right to a job at the expense of wellbeing of others.
Heathrow should REDUCE in size, not expand

N Warren, E. Twickenham, Middx

It is sheer madness on several grounds to allow any expansion of flights. The planet is running out of fuel so we should freeze flight numbers and airport size at current levels. Do any of us really want cheap flights if the price is aircraft flying over all our villages and houses, let alone rocketing heating bills and food bills.
Enough is enough. I would be happy to stop travelling if this is the cost.
Madness

Michel, Guildford,

More runways = less planes in the sky waiting to land!

Marcus, Guangzhou, China