Communities living near Stansted have been given an opportunity to discuss whether limits on airport passenger numbers should be lifted.
Some residents have campaigned against the expansion
Airport management BAA said it has applied to Uttlesford District Council to up the capped number of runway users from 25 million to 35 million per year.
In November, the council refused to lift the limit on the basis of climate change, noise and air pollution.
The public inquiry opens at the airport on 30 May and runs until 5 October.
Passenger number limits were previously increased from 15 million to 25 million in 2002.
In January, BAA announced plans for a second runway and terminal, which would increase passenger capacity and be open by 2015.