Heathrow Airport: Leaflets warn of runway use changes
People living under Heathrow Airport's flight path have been sent leaflets about changes to rules that allow the use of both runways simultaneously.
The runways are restricted to take-off or landing and switch each afternoon, except in an emergency, to give residents respite from the noise.
As part of a trial starting next month the threshold for triggering the emergency system will be lowered.
Airport operator BAA said it would allow it to minimise disruption.
A BAA spokesperson said leaflets had been sent to 150,000 homes that would be affected by the trials.
Under the changes, dual use can be deployed when a plane faces a 10-minute wait to land or take off and if 30% of all flights are delayed by more than 15 minutes.
The average time delay for flights at the west London airport is currently 12 minutes.
The first trial finishes on 29 February while the second will run from 1 July 2012 until 30 September - coinciding with the London Olympics.
John Stewart, chairman of the HACAN Clearskies campaign, said it was a major concern for people living in west London.
In the next few weeks campaigners will hand out thousands of leaflets at mainline and underground stations in areas that will be affected.
Mr Stewart said: "We will be informing people about the trials and urging them to get behind a campaign to make their views known to the government.
"They understand the reasons behind the changes but their critical half-day respite is going to be taken away."
The trial was recommended by the Department for Transport and will be overseen by the Civil Aviation Authority.
Tim Hardy, Heathrow's airside director, said the changes would allow them to test measures that could reduce the negative impact of disruptions on local residents, passengers and the environment.
He said: "Heathrow operates at near full capacity, meaning that even small disruptions can have a major impact on the flight schedule.
"It (the trial) will not result in any additional flights and could mean less unscheduled night flights, less airborne holding in the stacks and a more predictable and punctual service."
When the trial was announced in the summer aviation Minister Theresa Villiers said: "These measures have the potential to deliver greater reliability for passengers and reduce the impact of unscheduled night flights on local communities."
But she stressed the trial would include "effective engagement with local communities" and feedback from them would be central to any decision on whether to make the changes permanent.