Heathrow Airport is being permitted to use its two runways for both landings and take-offs, under a temporary relaxing of flight restrictions.
The Department for Transport backed trial means that more flights can land and take off in a shorter period of time, improving Heathrow’s capacity.
Usually, Heathrow’s two runways run on an alternating system, whereby one is used for take-offs and the other for landings, with the roles reversed at 3pm each day.
People living near the runways get a half-day respite from the noise of planes landing or taking off over their houses, but with over the next four months this is no longer guaranteed.
After the first trial period ends on February 29, a second phase will run during the Olympics.
When the experiment was announced in July, Theresa Villiers, Minister of State for Transport, said it would “deliver greater reliability for passengers”.
“Trialling these changes will allow their benefits and impacts to be assessed and there will be extensive engagement and consultation with local communities before any decision is taken on whether to make the changes permanent,” she added.