Foy, a retired events planner from Carmel, will end her six-year tenure on the airport board March 31 because she is moving to a new Carmel Valley home outside the district.
Other board members likely will appoint a new member to serve out the remaining two years of Foy's four-year term. That will come after the district advertises the vacancy for 15 days after Foy's tenure officially is over, district counsel David Willoughby said.
If the four board members can't agree on Foy's replacement, the vacancy would be filled by either Monterey County supervisors or in a special election, he said.
Foy announced her resignation at a meeting dominated by discussion of two major airport construction projects -- a new $1.7 million rental-car service facility and a $7.5 million interior overhaul of the airport terminal.
With board chairman Ron Phoebus absent, directors split 2-2 over the proposed location of the rental-car service facility, an issue that has dogged the board for two years.
In a prepared statement, Foy said the airport is in "a period of adjustment and transition" and cautioned board members to replace her with someone free of potential conflicts between personal business and airport affairs.
Calling the airport "the user-friendliest airport of its size in California," Foy said it became that way because of "a long history" of board attention to customers, stakeholders and master planning.
"I leave concerned that recent decisions reflect a shift to other priorities," Foy said.
In an interview, Foy said she is concerned the airport board is veering from a broad community orientation to an agenda more aligned with private pilots and general-aviation operations.
"I'm concerned the board is not as diversified as it should be," she said.
Phoebus is a training pilot who has worked for companies with airport land leases. Dana Petrak, who won election in November, is an owner of an aviation maintenance business at the airport. Longtime board member Dick Searle and Director Leonard McIntosh, who also won election in November, are private pilots with hangars at the airport.
In January, Foy suggested that the state Fair Political Practices Commission take an overall look at the board to ensure that decisions wouldn't run afoul of conflict-of-interest laws. Willoughby told her the state watchdog agency looks into specific cases and wouldn't conduct a general review, she said.
During a meeting break Wednesday, both Searle and McIntosh expressed regret that Foy is leaving the airport board.
"We're sad to see her go. She brought a lot of excellent business experience to the board," McIntosh said.
McIntosh said the concerns raised by Foy about board members being too close to airport business would "always be a consideration" in choosing her replacement.
Searle said, "She was a a good person who had a huge impact on the board."
Searle said airport directors should have experience in aviation to be effective.
"If you have a hospital you aren't going to bring in plumbers to run it," he said.
Any registered voter living in the airport district -- which runs from the Peninsula to Laureles Grade Road between Carmel Valley and the Monterey-Salinas Highway -- would be eligible to apply for Foy's seat, Willoughby said.