GATWICK airport has written to 320,000 residents reminding them that they would be affected by noise if Heathrow builds a third runway.
New areas that would be flown over include 16 local authority areas and London boroughs.
The letter is part of Gatwick’s own campaign for expansion, which it says would be cheaper and cause less disruption.
It also points out that users of the M25 would face major disruption if Heathrow expanded as the motorway would need to be squeezed into a tunnel to build the new runway over it.
The Airports Commission’s consultation closes on Tuesday.