As of August 2026, the government has backed a preferred design for a third runway at Heathrow, but nothing has been built and no flights use it. A draft national planning policy is due in summer 2026, with a Parliament vote expected in autumn 2026. Even on an optimistic path, the earliest flights are in the mid-2030s. Checked August 2026.
Where the plan stands in 2026
A third runway at Heathrow has been debated for decades. In 2026 the project moved forward again. The Transport Secretary set out support for Heathrow's northwest runway design, the option that would require rerouting and tunnelling part of the M25 motorway that currently runs across the site.
That backing is a policy direction, not permission to build. Before any construction, the scheme has to clear a formal planning process, and that is what is happening now. Treat the timeline below as the current expectation rather than a fixed schedule, because expansion projects of this size routinely slip and face legal challenge.
The timeline in plain terms
The next formal step is the Airports National Policy Statement, or ANPS, which is the document that sets the planning framework for airport expansion in the South East. The government is expected to publish a draft updated ANPS in summer 2026, followed by public consultation and parliamentary scrutiny.
Parliament is then expected to vote on the final ANPS in autumn 2026. If it passes, Heathrow would submit a Development Consent Order, the detailed application to actually build the runway and supporting infrastructure. That application is examined independently, with a final decision by the Secretary of State.
Putting those steps end to end, approval of the policy in late 2026 points to planning permission later in the decade and first flights no earlier than the mid-2030s. The often-quoted target of the early-to-mid 2030s assumes no major delay, which for a project of this scale is a large assumption.
What it would cost
The figures attached to Heathrow expansion are very large and vary between sources, so treat any single number with caution. The government's preferred northwest runway scheme has been costed at around £33 billion, and wider expansion of terminals and infrastructure pushes the total higher still. The runway would be funded privately by Heathrow rather than from public money, but the cost feeds into what passengers ultimately pay through airport charges, which is one of the points of dispute between the airport and the airlines.
What changes for passengers, and when
For anyone flying through Heathrow in the next few years, the honest answer is that little changes because of the third runway itself. There is no new runway to use, and day-to-day travel through T2, T3, T4 and T5 continues as now.
Over the longer term, if the runway is built, the airport would handle more flights and more passengers, which supporters say means more destinations and more competition on fares, while opponents raise noise, air quality and climate concerns. There would also be years of construction around the airport, including major roadworks to move the M25, which could affect driving and access while the work is under way.
Separately from the runway, Heathrow continues to invest in the existing terminals, and some airline moves have already happened, such as certain British Airways long-haul routes shifting from T5 to T3 from 29 March 2026. Those changes are about using today's terminals better, not the new runway. Always check your own flight's terminal before you travel, which you can do with our guide to finding your Heathrow terminal.
How to keep track
Because the position can change with each political and legal step, check the latest before drawing conclusions. Our Heathrow news feed tracks major developments, and the government and the airport publish the formal milestones as they happen. If you see a confident claim of an exact opening date, be sceptical: as of August 2026 no such date is fixed.
More
More: Overview, Facilities, FAQs.
Frequently asked questions
Has Heathrow's third runway been approved? Not fully. As of August 2026 the government backs a preferred design, but the formal planning process is still under way. A draft national policy statement is due in summer 2026 and a Parliament vote is expected in autumn 2026.
When will Heathrow's third runway open? There is no fixed date. On the current expected timeline, even without delays, the earliest flights would be in the mid-2030s. Projects of this size often slip, so treat any specific year with caution.
Which runway design has been chosen? The government's preferred option is Heathrow's northwest runway, which would require rerouting and tunnelling part of the M25 motorway that crosses the site.
How much will the third runway cost? Estimates vary and are large. The preferred northwest runway scheme has been costed at around £33 billion, with wider expansion pushing the total higher. It would be privately funded by Heathrow.
Will the third runway affect my flight soon? No. There is no new runway in use, so travel through the existing terminals continues as now. Over the longer term, construction and, eventually, more flights could follow if it is built.
We recommend a transport partner and may earn a referral fee. It never changes what you pay, and we only list options we would use ourselves.
Last verified August 2026 by the Heathrow Airport Guide editorial team. Prices and timetables change, so confirm the specifics on the official Heathrow Airport website before you travel.