The number of residents affected by noise from George Best Belfast City Airport would triple if the cap on seat sales was scrapped, a public inquiry has heard.
The inquiry is looking at the implications of getting rid of the Seats for Sales scheme, which limits the number of departure seats the airport can sell each year to two million.
Residents, represented by Belfast City Airport Watch (BCAW), and the City Airport have clashed for many years over noise control.
The main issue for the inquiry at the Planning Appeals Commission in Belfast is over whether a 'noise contour' control cap for the airport could replace the cap on sales.
The contour - the area affected by aircraft noise - is currently 4.2sq km, but under the airport's proposals it would extend to around 7.5sq km.
This would see the number of people affected by the airport's noise rise from 6,000 to approximately 18,000, a representative for BCAW pointed out.
This would create a great deal of "annoyance" and cause "health issues" for residents, BCAW told the inquiry.