Residents have until Dec. 18 to tell the county what they think of a proposed airport at the El Toro Marine Corps Air Station.
The county is seeking public opinion on plans that will be studied in an environmental report on the airport proposal.
Courtney Wiercioch, manager of the county's base conversion program, said it was in response to public comment that the Board of Supervisors chose the current plan.
"There is a general consensus that Orange County will need international air service by 2020 to remain competitive in the global marketplace," Wiercioch said.
An alternative plan favored by airport opponents also is available for public review. The Millennium Plan, put forward by the El Toro Reuse Planning Authority, calls for high-density development centered around commercial and residential projects.