BAA will this week throw its weight behind a controversial expansion of Heathrow when it announces it is joining Future Heathrow, a group that is lobbying for a new runway at the London hub.

The move represents a bold departure for the airports group, which has steered clear of publicly backing more flights at Heathrow.

Instead it has pushed forward with a new runway at Stansted – a planning application for this is expected later in the year. But executives have in recent months become confident that the air quality and noise issues that have stymied development at Heathrow can be overcome.

In October the government is expected to unveil a consultation document on expansion plans – including a new runway and an increase in flights on the existing runways. The airport already handles 67.7m passengers and 470,000 flights a year.

The consultation is expected to contain research by the Project for the Sustainable Development of Heathrow (PSDH), a group within the Department for Transport, that will provide snap-shots of the potential for development of Heathrow in 2015, 2020, and 2030. The research is understood to have already indicated that air and noise problems could be overcome for both a new runway and an increase in flights by 2020, even without taking into account possible plans to mitigate emissions by introducing such measures as a congestion charge on roads around the airport.

The unveiling of the plans is certain to provoke a storm of protest from antiairport and environmental campaigners, who are already mounting a strong battle against BAA’s plans for Stansted.

The framework for the expansion of southeast England’s crowded airports was set out in a white paper four years ago. It said Stansted should be given priority. Heathrow would grow only if problems with air quality and noise – which threatened to breach European health standards – could be overcome.

The work of PSDH has given BAA officials confidence this is the case.

Senior executives are also understood to believe that the economic benefits of developing Heathrow have grown in the intervening years, with evidence that the London hub, which is still the world’s busiest international airport, is losing traffic to continental rivals because of the extreme congestion on its runways and in its terminals.

An expansion of Heathrow could prove lucrative for the Ferrovial-led con-sortium that bought BAA last year.

Airlines at Stansted have opposed BAA’s plans for development there, saying they will cost too much and result in unacceptable rises in airport charges.

Heathrow airlines are all in favour of expansion at the airport. Take-off and landing slots at the airport are extremely scarce, and change hands for millions of pounds.

Future Heathrow, which is chaired by Labour peer Lord Soley, was set up two years ago to push for development at the airport. Its membership includes airlines, unions and business groups.

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