The government is backing a third runway at Heathrow—what happens next?

This morning chancellor Rachel Reeves gave official government backing for the construction of a third runway at Heathrow Airport, as part of a major speech on boosting economic growth. 

While the government claims the project could create more than 100,000 jobs and generate billions for the economy, there are still several hurdles ahead before construction can begin. Even if those hurdles are overcome, it will be several years—some reports have suggested 10 or more—before the runway is built and operational. 

The airport first needs to secure approval for a Development Consent Order (DCO)—a type of planning permission for nationally significant infrastructure. It has yet to do so.

Plans for a third runway previously received parliamentary approval in June 2018, but progress stalled after a legal challenge. The plans then did not progress following a fall in demand for air travel during the coronavirus pandemic.

According to the Planning Inspectorate, Heathrow’s application for a third runway is currently in the “pre-application” stage. A detailed breakdown of the stages that follow once an application has been submitted suggests it could take approximately 18 months before a decision—which will be made by the transport secretary—is announced.  

This is roughly in line with the timescale expected for Gatwick Airport, which submitted a DCO for an alteration to one of its runways on 6 July 2023 and is due to receive a decision by 27 February 2025. 

Despite the government backing for a third runway at Heathrow, it’s expected to face opposition from nearby residents, climate groups and London Mayor Sadiq Khan, and it’s likely the plans may then face legal challenges before any construction can begin.