Frustrated by the Federal Aviation Administration's persistent failure to address local concerns about airplane noise, and with a new airplane route proposed that would send more traffic over Palo Alto, the City Council agreed on Monday to consider filing a lawsuit against the agency.

By a unanimous vote, the council directed staff to schedule a closed session in the coming weeks to discuss the move.

Since 2014, when the FAA began consolidating flight paths over Palo Alto as part of its NextGen program, the city has been submitting letters, commissioning lobbyists and joining regional groups in an effort to get the FAA's attention -- only to see its concerns about airplane noise fall upon deaf ears.

Now Palo Alto is protesting the FAA's new Star Pirat Two route, which applies to planes coming in from the west over the Pacific Ocean. After approaching the coast, the route concludes at what's known as the ARGGG waypoint near Woodside. From there, some planes bound for San Francisco Airport would be directed to a newly created waypoint called SIDBY, which is directly over Palo Alto.

"You can see Palo Alto is basically a direct bullseye (for planes) coming in from where ARGGG is," Palo Alto Assistant City Manager Michelle Poche Flaherty said during a Monday discussion of airplane noise.

The FAA did make one promising gesture when it agreed to keep aircraft at an altitude of at least 8,000 feet over sea level at the Woodside waypoint. Even so, Palo Alto is expecting more noise from the agency's new plan. Flaherty noted that the route -- now seldom used and accounting for about 4 percent of local air traffic -- could be used by many more airlines, including those arriving to Oakland Airport.

"So we have expressed in a couple of letters to the FAA from the city that the Pirat Star route may indeed increase volume and we are concerned about what the community impacts might be of such volume increases," Flaherty said.

The latest of these letters, sent on May 6, urges the agency to be more transparent in its communications with communities under its flight paths. Signed by Mayor Eric Filseth, the letter lauds the FAA for some of its recent changes but raises concerns about the agency's latest plans.

"In addition to concerns about the lack of outreach, we are concerned that through the publication of Pirat Star Two, air traffic will increase in volume as more airlines will have access to the route," the letter states. "Traffic will also increase as aircraft en route to Oakland International Airport will also be able to use the route."

The city has a good reason not to expect a response. The FAA has consistently ignored the city's letters and requests for information, according to city officials. Last October, the city submitted a request under the Freedom of Information Act for background documents, including environmental analysis, justifying the changes. According to the city, the agency responded with a request that the city pays copying and search fees. When the city agreed to do so, the FAA informed it that the documentation would be made available by March 29, the deadline for comments on the Star Pira Two proposal (later, the agency delayed its release to a date beyond the March 29 deadline).

An in-person meeting in 2017 between three City Council members and FAA officials also proved to be a futile effort, with the Palo Alto contingent leaving Washington, D.C., exasperated by the agency's failure to respond.

Vice Mayor Adrian Fine, who participated in that meeting, on Tuesday described the city's work on airplane noise as a "tough, tedious and sometimes fruitless work." The progress, he acknowledged, has been slow.

"This really is a marathon rather than a sprint," Fine said.

To buy itself some time to respond to the FAA's new plans, the council agreed to request that the agency approve a "tolling agreement," effectively extending the comment period for its latest procedure changes, which the agency announced on April 25. Councilwoman Lydia Kou, who made the motion to "stop the shot clock," said the FAA should delay its final order until the city gets answers on the impacts of Pirat Two on Palo Alto, Menlo Park, East Palo Alto, Mountain View and Stanford University.

But mindful of the 60-day time comment period, Kou also suggested that the council meet in a closed session in early June to discuss possible legal actions against the FAA. The council unanimously supported both of her suggestions.

Residents also encouraged that the city take a more aggressive action against the FAA. As at prior meetings, dozens attended and many complained about the onslaught of noise that they have to endure.

Tom Shannon said he tracked 46 planes flying over his house over a five-hour period one morning earlier this month.

"That's nine per hour, or one every six minutes. ... There are people who are no longer able to sit on a deck and enjoy a cup of coffee without being interrupted every six minutes," Shannon said.

Osborne Hardison, a resident of south Palo Alto, observed that the city's history of writing letters to the FAA has proven to be unproductive. At what point, he aside, will the city actually consider suing the FAA?

"It seems like we're dealing with a fixed game and they have no incentive at all to listen to our needs," Hardison said.

The council concurred and agreed to meet with its attorneys a closed session on or before June 10. This will be the second time in a little over a year that the council is considering a lawsuit against the FAA. In April 2018, the council met in a closed session and ultimately opted not to sue, reasoning that it would be more productive to forge partnerships and address the issue as a region.

That approach has borne some fruit. Palo Alto and other cities in Santa Clara and Santa Cruz counties have recently formed a roundtable group devoted to the subject of airplane noise. The group is similar to the San Francisco Airport Roundtable, which limits its membership to San Francisco and San Mateo counties. Palo Alto has also collaborated with San Francisco Airport on installing noise monitors around Palo Alto to gauge the level of aircraft noise.

To date, however, stronger alliances have not translated to success. Councilwoman Alison Cormack observed on Monday that airplane noise is a difficult problem and the city has few options.

"I know people are frustrated and I hear those frustrations," Cormack said.