The aircraft noise map

Users of the site, created by airports operator BAA, enter a postcode and a time of day and are presented with a map showing which planes are flying over their homes and when.

Part of BAA's £1.8 million investment in noise-tracking systems, the WebTrak tool contains details of flights to and from Heathrow, Gatwick and Stansted and lets people complain about aircraft noise online.

Vicki Hughes, Stansted's noise communications manager, said: "The launch of this new noise website is another positive development in the open way in which we work with local communities to share as much information as possible about Stansted's operations.

"This significant investment demonstrates how fully committed we are to providing the best possible service to membersof the public about noise and aircraft track-keeping."

The site shows flightpaths the planes are following along with information on the type of aircraft, its speed and altitude. There is a 24-hour delay on the data for security reasons.

John Stewart of aircraft noise campaign group HACAN said: "The visual images are dramatic. They show planes crisscrossing the skies of London and the Home Counties and illustrate that aircraft noise is no longer just a problem for areas close to Heathrow. It will enable people to see for themselves exactly what is going above their heads."

However, Mr Stewart said that some parts of London were missing from the system.

"The one oddity of WebTrak is the way that parts of east and south-east London are not covered by it," he said. "HACAN will be issuing a report later this month which will show the dramatic way noise has increased in many of these areas over the past decade. They need to be added to the system."

A public inquiry into plans to expand Stansted airport was due to open today, with environmentalists calling for the scheme to be abandoned.

Officials at BAA said the inquiry - which is looking at plans for an immediate increase in the number of flights allowed at the Essex airport rather than calls for a second runway - is likely to run for six months.

BAA wants to increase the number of passengers using the airport from 25 million a year to 35 million with a rise in the number of flights from 80,000 a year to 264,000.

Greenpeace spokeswoman Emily Armistead said: "Our Government has to join the dots and call a halt to airport expansion - if they don't there's no way we are going to ward off catastrophic climate change."

BAA said environmental concerns had been taken into account.