The county filed a petition earlier this month in federal court to join the suit that seeks to prevent the FAA from changing the paths of arriving and departing flights, the Los Angeles Times reported Saturday.
The petition argues the proposed changes could lead to a significant increase in jet noise for the areas surrounding the county-owned-and-operated facility.
"We have an absolute duty to speak up for citizens who will be affected by airport noise, and Newport Beach has been so aggressive in doing that. We as a county need to be right alongside it," said county Supervisor Todd Spitzer.
The action was prompted by an environmental impact review the FAA conducted in connection with plans to replace an outdated, ground-based air traffic control system with a GPS-based one at 21 airports, including John Wayne.
The report concluded that changing flight patterns to accommodate the system would cause no significant impact.
But county officials say a consultant hired by the airport to study that review told them it was inadequate, adding he couldn't determine from it what the impact would be.
FAA spokesman Ian Gregor said the agency does not comment on pending litigation. However, he added that it focuses on balancing local communities' concerns with the need for advanced air traffic systems.
The county board's vice chair, Michelle Steel, said it's crucial that county residents clearly understand how any changes in flight patterns will affect them.
"Our residents are the ones who live every day with aircraft operating overhead," said Steel, who represents Costa Mesa, Newport Beach and other areas in the path of planes leaving the airport.