The government says it wants to expand Heathrow Airport and has put its plans out to consultation. Here are some of the main points:
Ministers have already said they support in principle, a third runway at Heathrow, as outlined in the 2003 White Paper. That support was conditional on there being no increase in the size of the area significantly affected by aircraft noise - judged to be at 57 decibels - and on any expansion meeting EU air pollution limits, as well as improvements to public transport to the airport.
WHY DO MINISTERS WANT HEATHROW EXPANDED?
The government says Heathrow is a major contributor to the UK economy, but its runways are full and its route network is shrinking. It says rival European airports have leapt ahead and that a third runway at Heathrow would bring "net economic benefits" of about £5bn, taking into account climate change and noise costs.
WHAT IS BEING PROPOSED?
A 2,200-metre runway, to be built north of the A4. It is slightly longer than the original proposals for a 2,000 metre runway. A longer runway was ruled out in 2003. Heathrow owner BAA also wants a sixth terminal, with direct access to existing rail services, which would reduce the need for aircraft to taxi across the existing northern runway.
WHAT ELSE IS PROPOSED?
As an interim measure, the government supports the idea of the existing two runways being used for both take-offs and landings - known as "mixed mode" - currently the "alternation" method sees planes landing at one runway until 3pm and then on the other one for the rest of the day to give residents near each runway half a day's break from noise. This could allow 60,000 more flights a year and could be done by 2015. It would also generate 4.5 million extra Tube journeys to Heathrow, 4 million more train journeys and 25 million extra car journeys.
SO HOW MANY MORE FLIGHTS WILL THERE BE?
BAA argues the changes could allow the airport to handle about 700,000 take-offs and landings a year. This would be about 50% more that at present.
WHAT ABOUT THE ENVRONMENTAL IMPACT?
Analysis outlined in the consultation says three runways could be operated by 2020, with about 702,000 take-offs and landings, and meet air quality limits - thanks to developments like cleaner aircraft engines, and more twin-engine rather than four engine aircraft. The government says an international emissions trading regime for aviation was the best way to make sure there is no overall increase in aviation emissions. It also says it is looking into ways of making Air Passenger Duty more relevant to distances travelled.
WHAT ABOUT NOISE?
Flight numbers would have to be limited to meet noise restrictions, until older, noisier aircraft are retired. From 2020 it estimates there could be 605,000 take-offs and landings a year to meet limits. This would then gradually increase to 702,000 by 2030. Night flight restrictions, which are next due to be reviewed in 2012, will not be addressed in the consultation.
WHAT ABOUT THE LOCAL AREA?
The proposals would mean 700 properties will have to be destroyed - including the village of Sipson. There would also be an end to the Cranford agreement, which restricts planes taking off over Cranford, to the east of the runway, which would mean "some redistribution of noise around the airport". Cranford would get more flights, while parts of Feltham and Windsor would get less. The documents state that, if the existing runways were turned over to the "full mixed mode" method by 2015, 20 schools near Heathrow would experience noise levels at or above 63 decibels - currently it is 14 schools. It would also get noisier in Egham, Putney and Barnes, but quieter in Windsor, Slough and Twickenham.
HOW TO TAKE PART IN CONSULTATION
The consultation runs from 22 November 2007 until 27 February 2008. A series of public exhibitions are taking place around Heathrow. More details, and the chance to comment on the proposals, are available on the Department for Transport website: