The Government is to choose which scheme to back after a review of the UK's airport capacity. Here are the three shortlisted options:
- A third runway at Heathrow
Sir Howard Davies's Airports Commission recommended a third runway should be built at Heathrow in July last year.
The plan would cost £17.6 billion but an additional £5 billion of improvements to road and rail links would be necessary to enable the extra passengers to travel to and from the airport.
Some 783 homes would be demolished for a third runway, including the entire community of Longford and much of Harmondsworth.
The expansion would generate about 77,000 new jobs by 2030.
Sir Howard's report predicted the scheme would lead to 138 million air passengers each year by 2050 - up from 75 million in 2015.
- A second runway at Gatwick
Ministers are considering the building of a new runway at Gatwick costing £7.1 billion.
The proposal involves 167 homes being lost - which is the lowest out of the three options.
And a second runway would be expected to lead to 32,000 additional jobs by 2050.
The West Sussex airport claims it is the only scheme that does not require taxpayer funding and has attempted to discredit a number of findings made by the Davies Commission.
The Airports Commission claimed surface access improvements would cost £800,000 and the expanded airport would be used by 82 million travellers each year by 2050, compared with 42 million today.
Gatwick argues that London needs "two world-class airports", adding cities such as New York, Paris and Tokyo do not rely on one "mega hub" for all air travel.
- An extended runway at Heathrow
A second shortlisted option for Heathrow involves extending the west London hub's existing northern runway to form the equivalent of two runways.
This £14.4 billion proposal was put forward by Heathrow Hub - a consortium that includes former Concorde pilot Jock Lowe.
Its supporters claim planes would be able to simultaneously land on one of the runways and take off from the other.
They say this would provide the benefits of increased capacity while avoiding "significant new communities" being brought into the noise footprint of flights.
According to the Airports Commission the number of passengers using the airport each year would jump to 131 million by 2050.
The increased capacity would support 77,000 new jobs by 2030.
The cost of improving surface access would be £5.5 billion and 242 homes would be lost.