Because Surf Air's Pilatus PC-12s carry fewer than nine passengers, under FAA regulations they may operate out of the San Carlos Airport even though it is a general aviation not a commercial airport. The airport is considered a "reliever airport," keeping small planes out of busy regional airports such as San Jose, San Francisco International and Oakland.

Complaints about airport-related noise began pouring in soon after Surf Air began using San Carlos Airport for scheduled flights in June 2013. The airline offers customers unlimited flights for a monthly fee and has had as many as 45 scheduled flights a day to or from the airport.

Those who live under the flight path of Surf Air's noisy turboprop commuter aircraft are so upset about the county's lack of progress that they have scheduled a protest march at the San Carlos Airport for Saturday, June 17.

More than a year after San Mateo County started a study meant to figure out how to address the noise complaints pouring in about San Carlos Airport -- mostly with regard to Surf Air -- a solution remains elusive.

An aerial view of the San Carlos Airport taken from a drone, which airport management says had permission to take the photo while the runway was closed. Residents upset about noisy Surf Air planes have scheduled a protest at the airport June 17. (Photo courtesy San Carlos Airport)

• Purchasing an automated system to track planes near the airport, so county employees no longer need to spend 10 to 20 minutes per noise complaint figuring out which aircraft was involved. (Gretchen Kelly, the airport's manager, says in the past 90 days 6,492 noise complaints were filed from 193 households. About 40 percent are about aircraft not using San Carlos Airport, she said.)

• Hiring a consultant to determine if there is a flight route that will let aircraft use the San Carlos Airport while avoiding residential areas, both in good weather and bad.

The county's growing number of employees who are addressing the airport problems say they are also frustrated, but a solution may still be more than a year away. Later this month the Board of Supervisors plans to consider spending more on the search for a solution by:

Mr. Callagy said if an alternative route can keep aircraft from residential areas, the curfew won't be needed. However, if a consultant finds such a route, the necessary FAA approval process could take as long as two years, industry experts say.

Deputy county counsel Brian Wong said lawyers have "looked really closely" at a proposed curfew ordinance and believe they can craft one that will stand up to legal challenges which could come from the federal government, Surf Air or other airport users. "We want to be careful," Mr. Wong said, and to explore other possible solutions.

Assistant County Manager Mike Callagy said, however, "there is no agreement." A curfew, he said, "is still on the table" and the county will continue considering it.

The issue was muddied when the San Carlos Airport Association, representing some of the 25 businesses and the pilots operating out of the airport, issued a press release on May 18. The statement said the county, Encompass Aviation (a subcontractor that took over Surf Air's flight operations on May 15) and the airport association had reached an agreement "in principal" that included a county promise "to drop any further discussion of the proposed curfew ordinance, entirely and permanently."

In the meantime, the county's work on a possible curfew on noisy planes, limiting hours and numbers of flights for certain aircraft, has moved to the background while the county investigates other possible solutions.

The study of "aircraft disturbance" at the San Carlos Airport was approved by county supervisors in March 2016. It was originally scheduled to be completed by that June, but the county has repeatedly delayed presenting the results of the study.

Check FOBAneighbors.org , or NextDoor for the location, which may be changed from the usual meeting space at the Riekes Center on Edison Way in Menlo Park to allow for more attendees.

The Fair Oaks Beautification Association (FOBA) will also discuss the Surf Air noise disturbances and possible involvement at its next monthly meeting at 6:30 p.m. Tuesday, June 13.

"The purpose of the protest is to encourage Surf Air to significantly curtail the disruptive noise disturbances their planes create or to cease San Carlos Airport operations completely," said organizer Aidan Yeaw, a resident of North Fair Oaks who worked with the CalmTheSkies group to organize the protest.

The protest march will be held on Saturday, June 17, from 9 a.m. to noon at Surf Air's San Carlos terminal, 701 Skyway Road, San Carlos, a date and location the organizers arranged with airport management. Parking will be available at 795 Skyway Road, and there will be restrooms and shade.

This has resulted in some head-scratching situations including Surf Air's May 18 announcement that it is adding 12 round-trip flights to San Carlos, which Encompass said they knew nothing about.

County officials say they have no idea who is currently running Surf Air and they have been communicating with Encompass employees.

County officials say they were told by Surf Air workers that CEO Jeff Potter and senior vice president of operations Jim Sullivan have left the company. An email to Mr. Potter received an auto-reply: "I have transitioned from my role as President and CEO of Surf Air" with a new email address. He did not reply to an email to the new address.

San Carlos Airport noise solutions prove elusive

Residents and county employees are frustrated by noisy aircraft