PLANS for a third runway at Heathrow, the world’s busiest international airport, flout safety guidelines by placing a proposed crash-landing zone on top of a motorway junction.

The mis-siting emerged in an investigation by The Sunday Times into the expansion of Heathrow. The investigation also revealed that figures for carbon emissions and the impact on air quality have been downplayed. The government is under pressure to rethink the £12.7 billion project.

BAA, the airports operator, has decided that the risk of a plane crashing into the six-lane motorway, which rises to 65ft (20 metres), does not merit relocating the M25/M4 junction.

Opposition to the scheme is being led by Hillingdon council, the planning authority for Heathrow. It states that expansion should be “rejected outright on safety grounds”.

The government is likely to be challenged in the courts if it approves plans for the development this summer. Its own guidelines state that the number of people in “public safety zones” around airports should be kept to a minimum. They say: “The basic policy objective . . . is that there should be no increase in the number of people living, working or congregating in public safety zones.” This should apply because of the extra traffic generated by the enlarged airport.

The Department for Transport (DfT) has been advised to create ways of avoiding traffic jams on the junction to reduce the risk of fatalities in a hypothetical plane crash. Most crashes occur during landing or take off. In January, a British Airways jet crashed after its engines failed during its descent to Heathrow.

The official submission by Hillingdon to the DfT says: “Government guidance states that density of occupation of a six-lane motorway is similar to that of a housing development . . . Such transport developments should not be permitted within public safety zones.”

Ruth Kelly, the transport secretary, was criticised this weekend for failing to publish maps showing that the M25/M4 is within the safety zone, the area with the highest crash risk.

Campaigners are now calling for an independent review. Justine Greening, a Conservative frontbencher, said: “Yet again a key aspect of expanding Heathrow that the public need to understand was left out from the consultation document.”

Documents released under the Freedom of Information Act show the Civil Aviation Authority has raised concerns about the potential conflict with air traffic from nearby RAF Northolt.

Another of the authority’s concerns was a proposal to reduce from 90 seconds to 60 seconds the gap between planes taking off in the same direction from the two existing runways.

CAA's concerns over Heathrow expansion

Hillingdon Council response to the government's consultation document

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