Heathrow third runway: What's the plan for expanding the airport?

After years of intense debate, UK Chancellor Rachel Reeves is expected to welcome the expansion of Heathrow Airport on Wednesday. Simultaneously, expansion plans for other London airports, including Gatwick and Luton, are also being confirmed, though these moves are likely to face strong opposition.

Critics argue that increasing air travel will make it harder for the UK to meet its climate change commitments. However, Chancellor Rachel Reeves stated in a BBC interview: "Sustainable aviation and economic growth go hand in hand."

Heathrow is currently the UK’s busiest airport, with four passenger terminals and two runways, serving over 80 million passengers annually. A third runway would mean demolishing hundreds of homes, diverting rivers, and re-routing the M25 motorway between junctions 14 and 15 via a tunnel under the new runway.

Currently capped at 480,000 flights per year, expansion could increase this to 720,000, averaging nearly 2,000 flights per day. Heathrow told the BBC that once the third runway is operational, it could eventually serve up to 140 million passengers annually. The airport's owners, including sovereign wealth funds from Saudi Arabia and Qatar and private equity firm Ardian, say the cost of expansion will be borne by charging airlines more for using the larger airport. However, after years of wrangling over the initial plans, the initial estimated cost of £14 billion needs to be revised.

Even with government backing, the formal planning process could take up to two years. Any planning decision is likely to be subject to judicial review and will need to answer environmental concerns raised by objectors. Local authorities and nearby residents will also have questions. Construction is then expected to take a further six to seven years.

Plans for a third runway were first proposed by the Labour government under Gordon Brown back in 2009 but only finally received approval from the Supreme Court in 2020. Several members of the current government, including Prime Minister Sir Keir Starmer, voted against the expansion of Heathrow when in opposition. However, there have been recent indications that a Labour government would support a third runway. Starmer told the BBC that the government has commitments to tackle climate change, "but economic growth is also really important." Energy Secretary Ed Miliband said: "Any aviation expansion can only happen if it is consistent with our carbon budgets."

However, the office of London Mayor Sadiq Khan said he has "long opposed airport expansion around London" because of the impact on air quality and noise. Heathrow's chief executive, Thomas Woldbye, said in December that he was waiting for "clear direction" from the government before progressing with plans.

Some of the arguments for investing in the UK’s transport infrastructure include boosting economic growth, increasing employment, and helping UK exports. Other European cities have hub airports with more runways, including Amsterdam, which serves fewer passengers than Heathrow but has five runways. Paris Charles de Gaulle and Frankfurt have four runways. Currently, more than £200 billion of UK trade passes through Heathrow annually. Heathrow has yet to develop figures for how much trade is expected to increase once the third runway is built, which will be done as it moves into the planning phase.

The Airports Commission, an independent body that reviews the need for extra airport capacity in the UK, reported in 2015 that the expansion of Heathrow would bring £61 billion in benefits over 60 years. This includes lower fares, reduced delays, improved resilience, and the creation of up to 77,000 jobs. Pushing ahead with the expansion of Heathrow would also send a clear message to foreign investors that the government is serious about prioritizing growth. However, some critics, including the think tank New Economics Foundation, say the impact on economic growth has been overstated, and they argue that more capacity in the south of England might just move activity from other regions.

Aviation is one of the harmful sources of emissions that contribute to climate change, and the industry is under pressure to find ways to reduce its impact. Reeves pointed to progress being made in creating sustainable fuels and electric aircraft. She added that a third runway at Heathrow would also mean "planes can land rather than circle over London," which means reduced fuel use. But it is far from certain that these technologies will be enough to compensate for the growing demand for air travel. Heathrow must demonstrate that its plans are consistent with the government’s target of net-zero emissions by 2050 in any planning application.

Last year, the government’s independent climate advisers, the Climate Change Committee, warned that the UK should not proceed with airport expansions without a framework for managing national capacity. The group Friends of the Earth described the plans for a third runway as "grossly irresponsible." Alethea Warrington, head of aviation at the climate charity Possible, said: "This huge increase in emissions will not help our economy, it will just encourage the small minority of frequent flyers who take most of the flights."

Expansion plans for other London airports are progressing faster than Heathrow’s and have previously been considered as alternatives to a third Heathrow runway. Terminal expansion work at Stansted is due to begin this year. The government is due to make a decision on Gatwick by February 27. Gatwick wants to increase its capacity to 75 million passengers a year, according to previously published plans. Before the pandemic, its highest record was 47 million. Meanwhile, a decision on the expansion of Luton Airport, which includes plans for a new terminal, is due by April 3. In total, these expansions could create capacity for more than 60 million extra passengers by the 2040s.