London Heathrow has officially submitted its expansion plan to the UK government, including the controversial building of a third runway at the country¡¯s largest airport.

The privately owned airport, which received government backing for an additional runway in January, said the new 3.5-kilometre north-western runway would allow it to increase capacity from its current level of around 84 million passengers per year to 150 million annually by the mid-2030s.

In a statement, Heathrow said the runway, which now has an estimated cost of ?21 billion (up from ?14 billion in 2018 due to ¡°construction inflation), would be part of a wider ?49 billion expansion of its infrastructure.

Other elements of the project include a new T5X terminal alongside Terminal 5 ¨C seen by the airport as a ¡°new second front door¡± to the existing terminal.

Heathrow will also expand Terminal 2 and add three satellite terminals, which will allow a phased closure of Terminal 3. The airport added that this part of the project would go ahead even if the third runway is not built.

The airport previously secured parliamentary approval to build a third runway in 2018 under the former Conservative government. But these plans were eventually shelved after a series of legal challenges and the impact of the Covid-19 pandemic.

Heathrow¡¯s CEO Thomas Woldbye said:?¡°It has never been more important or urgent to expand Heathrow. We are effectively operating at capacity to the detriment of trade and connectivity.

¡°With a green light from government and the correct policy support underpinned by a fit for purpose regulatory model, we are ready to mobilise and start investing this year in our supply chain across the country.¡±

The latest expansion plans are also set to face legal and political challenges in the next few years. Although Heathrow says the new runway could be operational within a decade.

Heathrow emphasised that the project would be ¡°100 per cent privately financed¡±. Although, airlines fear they will face higher airport charges to pay for the expansion, which is likely to lead to increased airfares.

An alternative expansion plan for the airport has been put forward by hotel tycoon Surinder Arora, which includes a shorter and cheaper 2.8-kilometre runway.

Heathrow¡¯s expansion proposals will now be considered by the government with the aim of reviewing the Airports National Policy Statement, which would effectively green light the project, later this year.

UK transport secretary Heidi Alexander said: ¡°I am pleased to have received the initial Heathrow expansion proposals - a significant step towards unlocking growth, creating jobs and delivering vital national infrastructure to drive forward our plan for change.¡±

Airlines association IATA welcomed the UK government¡¯s support of Heathrow expansion but questioned the recent performance of the airport¡¯s current operator.

¡°We applaud the government¡¯s decision to support the UK¡¯s global aspirations by advancing plans to expand Heathrow,¡± said Willie Walsh, IATA¡¯s director general. ¡°This must not, however, come at any cost or make any assumption that the current operator is best placed to deliver the value that the UK¡¯s economy will critically need for growth.

¡°The March closure of the airport was an embarrassment on the global stage that leaves little room for confidence in the airport¡¯s management.¡±