AN investigation was launched today after a packed Gatwick-bound plane came within four seconds of a mid-air collision.

The near-miss happened over the Thames estuary early yesterday when a British Airways 737 and a United Airlines 777 were found to be heading towards each other at about 400mph.

It was only when automatic warning messages flashed on both planes that crews were alerted.

A spokesman for the Civil Aviation Authority said the incident had not been reported to them yet, but the pilots of both planes had 96 hours from the time of the incident to do so.

The BA jet had more than 140 passengers and was preparing to land at Gatwick following a flight from Gothenburg, Sweden.

It was circling while waiting for clearance to land and was in the same holding stack as the United plane which was waiting to land at Heathrow following a flight from America.

Warning lights and instrument panels on both planes lit up and the BA plane climbed higher while the United Airlines descended.

Reports say both planes were on the same flight level and were only a few hundred feet apart, missing each other by four seconds.

Yesterday's incident has again sparked concerns about the increase in the number of planes in the skies over the South East and whether the air traffic control system at West Drayton in Middlesex can cope.

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