A Grounded Perspective on Heathrow’s Proposed Third Runway

Written By Anna Pringle

Setting the Flight Path

Heathrow Airport has been a gateway to international travel and commerce since 1947. In 2024, Heathrow was ranked the fourth busiest airport in the world, as calculated by the statistics company, OAG Aviation [1]. Heathrow recently confirmed a multi-billion-pound investment to expand two terminals and build a third runway [2]. The Chancellor Rachel Reeves vocalised her support for the expansion in January 2025 stating that “this will make Britain the world’s best-connected place to do business”. However, Heathrow’s plans are facing opposition.

First-Class Boost

Heathrow has been operating at full capacity for over 20 years. The Department of Transport has forecast that, ‘as many as 100 million UK passengers per year may not be able to fly by 2050 due to capacity constraints at Heathrow’ [3].

The third runway aims to introduce 40 new routes and increase the frequency of existing routes. This will result in more business travel and tourism, which in turn can help boost productivity and GDP in the UK. In 2023, 15 million business travellers used Heathrow, and over £30 billion was spent by tourists visiting the UK that year [4].

The expansion will enable increased long-distance trade with the UK’s trading partners, which is vital following the UK’s departure from the EU. Air freight is carried in the holds of passenger and cargo aircrafts, representing 57% of the UK’s non-EU trade [4]. Currently, over £200 billion worth of air freight travels through Heathrow Airport each year [5].

The plans are anticipated to create over 100,000 direct jobs for engineers, construction workers and project managers, as well as many indirect jobs. In addition, Frontier Economics has calculated that 60% of the economic benefit will be felt by those outside of London and the South East, as a result of lower fares and greater options for passengers [4].

Carbon Flight Print

However, Airports Commission (AC), an independent body established by the Government, have estimated that the third runway will increase carbon emissions by 4.4m tonnes. AC have also calculated that 28,000 more people would be exposed to noise pollution exceeding 70 decibels. The expansion would require the diversion of five rivers, rerouting the M25 and demolishing 800 homes [6].

It should be noted that the AC’s assessment was conducted in 2017, and since then there has been significant developments in sustainable aviation fuels. In addition, Heathrow launched their ‘Connecting People and Plant’ sustainability strategy in December 2024, which aims to achieve net-zero emissions by 2050, address biodiversity loss and improve air quality around the airport [7].

Sky-High Price Tag

The cost of the third runway has also raised concerns, particularly following the construction of HS2, in which the budget has surged by £100 billion. The estimated cost of Heathrow’s expansion is £30 billion, due in part to the demolition and rebuild of local housing and the rerouting of the M25 [8]. However, Heathrow have confirmed that the project will be 100% privately funded, with no cost to the UK taxpayer. 

Will it Land?

To grow the UK’s economy, it is vital that airports such as Heathrow remain an international gateway for trade and tourism. However, as acknowledged by the CEO of Heathrow, Thomas Woldbye, economic growth and prosperity must be balanced with climate conditions. To be successful, Heathrow should continue to encourage the adoption of sustainable aviation fuels, the reduction of noise disturbance and the maintenance of local biodiversity.

Co-authored by Anna Pringle and Shyam Popat

Anna Pringle
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