Runway plans that could see a huge increase in the number of flights at either Heathrow or Gatwick have been outlined by the bosses of the two airports.
The £15.6 billion Heathrow plan for an extra, third, runway - if recommended by the Whitehall-appointed Airports Commission - would see the number of annual flights at the west London airport increase from 472,000 to 740,000 by around 2030.
The £7.8 billion plan at Gatwick would see a second runway built at the West Sussex airport, with an extra 260,000 flights a year by 2050 compared with 248,000 a year now..
In submissions to the commission, Heathrow said its plan would create 100,000 new jobs, with Gatwick chiefs saying their plan will create 120, 000 new jobs.
Initial plans by both airports made it on to a shortlist chosen by the Whitehall-appointed Airports Commission. The revised plans will now be considered by the commission which will recommend which scheme gets the go-ahead when it makes a final report in summer 2015.
Also on the short list is a rival Heathrow scheme put forward by Heathrow Hub, a group of civil engineers which includes former Concorde pilot Jon Lowe.
Theirs is a proposal to extend the existing northern runway to at least 6,000 metres (20,000ft). They are also submitting a more detailed plan to the commission this week.
Today's revised Heathrow plans envisage a third runway built by 2025 which could provide at least £100 billion of benefits for the UK economy. Under the new plan, there would be a third runway located further south than originally planned which will mean the number of homes needed to be compulsorily purchased - in the village of Harmondsworth - dipping from 950 to 750.
The revised plans also mean the number of people affected by significant noise will fall from 177,000 to 165,000.
A third runway would take the number of annual flights at Heathrow up from the current 472,000 to 740,000 and there would be 40 new daily routes to destinations with fast-growing economies.
As previously announced, Heathrow's revised submission includes an improved compensation plan for those affected by the runway. Heathrow is allocating £550 million for noise insulation and property compensation and will launch a consultation with local people on proposals this summer.
The third runway will necessitate the building of a 2,000ft tunnel on the M25 which would be widened to seven lanes in each direction on the stretch between junctions 14 and 15 near Heathrow. The airport's chiefs said today that this work, taking three to four years to complete, could be done without having to close part of the motorway.
The Heathrow bosses said their scheme was the only way forward for the country and for UK aviation, a claim also put forward today by Gatwick chiefs who are submitting a 3,200-page report to the commission.
Gatwick bosses say the second-runway plan:
:: Will enable more people to fly to more destinations - 10 million more passengers each year will be able to travel with a second runway at Gatwick than with a third runway at Heathrow;
:: Will generate more competition, keeping fares low, and delivering £40 billion more in economic benefits to the UK than expansion at Heathrow;
:: Can be delivered about five years earlier than a third runway at Heathrow at no additional cost or risk to the taxpayer;
:: Will deliver more than 120,000 jobs in London and south east England, rebalancing the economy away from an overheated M4 corridor;
:: Means far fewer people will be affected by noise - a second runway at Gatwick would have an impact on only 14,000 people compared with the 240,000 people impacted by noise from Heathrow today.
Heathrow Hub said today it had also finalised a detailed submission to the commission.
Its submission says:
:: No "third runway" will be built to the north of Heathrow - instead there will be an extension of the existing runway to add capacity;
:: Its plan would mean a potential end to night quota flights as part of world-class noise mitigation strategy;
:: A major new passenger facility will connect Heathrow to the national rail network via 30 trains an hour;
:: There will be up to £45 billion of economic benefits for the UK and 19,000 jobs;
:: There will be no closure of the M25 and a new junction to disperse traffic impact.
John Holland-Kaye, Heathrow's development director and chief executive designate, said: "Expansion at Heathrow matters to the whole country. Only Heathrow will connect all of the UK to fast-growing international markets. The plans we are submitting to the Airports Commission demonstrate major economic benefits from a third runway for the whole of the UK."
Stewart Wingate, Gatwick's chief executive, said: "As we reach this critical point in the aviation debate it is clear that the Airports Commission has a very real choice to make: expand Gatwick and create genuine competition in the market with lower fares for everyone, or move back to a London airport market dominated by a single player and saddle the next generation with higher air fares."
Launching the Heathrow Hub plan today, Mr Lowe said: "Our proposal is the most efficient, cost-effective and politically realistic of the three proposals shortlisted by the commission.
"We offer the best solution to local communities concerned about noise or compulsory purchase of homes, and via our new railway and passenger hub can at last connect Heathrow to the national rail network and better accommodate the arrival of new passengers.
The option of a new airport in the Thames Estuary - the so-called "Boris Island" scheme favoured by London's Mayor Boris Johnson - did not make the shortlist drawn up by the commission which is headed by former Financial Services Authority chief Sir Howard Davies.
But the commission is still studying the scheme and is expected to make a decision later this year on whether the project should be taken forward.
Today, Mr Johnson's chief aviation adviser Daniel Moylan rubbished the rival plans, saying the estuary airport plan was "the only credible option".
The CBI said it was important that politicians were "ready to make a final decision" once the commission reported in summer 2015.
The Woodland Trust said that ancient woodland will be destroyed in every single option that Gatwick had put forward. and that a ny expansion at Heathrow would directly affect a number of historically important ancient trees including the 1,000-year-old Harlington Yew.
Nikki Williams, the trust's campaigning head, added: " These proposals serve as yet another example of why ancient woodland needs better protection from national infrastructure."
John Stewart, chairman of Heathrow residents' group Hacan, said it was " an Alice-in-Wonderland fantasy to argue that over quarter of a million planes extra a year will not bring greater noise problems for most residents under the flight paths".