General aviation groups are bracing for the ramifications of the looming closure of air traffic control towers at nearly 240 airports, loss of upkeep of navigational aids (navaids) at many of those airports and a reduction in controller staff as FAA implements rolling furloughs.

But as sequestration officially took effect March 1, confusion still existed on what exactly would be affected and when.

FAA’s share of the sequestration cuts for the remainder of fiscal 2013 would be $600 million – accounting for 60% of the Department of Transportation’s total sequester cuts. This is a disproportionate share, since FAA makes up only about 20% of DOT’s budget. But FAA Administrator Michael Huerta told Congress last week that’s because “a very large portion of the DOT’s budget is exempt from the sequester.”

Not only does the sequester mandate the protection of most of DOT’s budget, it also shelters a great portion of FAA’s budget, including airport grants, most facilities and equipment and some research, engineering and development. This leaves FAA’s operations account vulnerable to most of the sequester cuts.

FAA told stakeholders last week that the agency was evaluating options, but indicated a large number of towers would close, while many others would be shut during nighttime hours. Questions remained on which towers and when.

FAA initially indicated that the closures would potentially affect 100 towers, but the number has grown to close to 240 – the vast majority of which are contract towers. Contract towers are slated to close first, as soon as April, while federally-run towers on the closure list may stay open until September, says Heidi Williams, vice president of air traffic services and modernization for the Aircraft Owners and Pilots Association (AOPA).

But in a blog post, AOPA President and CEO Craig Fuller says the cuts are still a “moving target … we have yet to see a comprehensive sequestration plan and timetable.”

Fuller adds the association still has few details about precisely what that means for general aviation. “Unfortunately, even the people who make those decisions still aren’t entirely clear on what happens now,” he says.

AOPA, along with other general aviation groups, are watching closely because what has been clear is that general aviation likely will feel the brunt of those cuts. Most of the affected towers have fewer than 150,000 annual operations. FAA is also looking at scaling back maintenance of navigational aids at numerous airports, including those scheduled to lose airport towers.

Whether that could affect safety at those airports is “the million dollar question,” Williams says.

But Fuller stresses “airports will remain open [and] many GA flights can and will proceed as normal, even if some towers are closed.”

AOPA is also concerned that the rolling furloughs – once every 10 working days for most FAA employees – will mean a cutback at en route facilities. “Controllers at towers and en route facilities help pilots avoid trouble every day – something most of us know from firsthand experience. And that’s where sequestration may really hit hard,” he says.

Beyond the small airports, the National Business Aviation Association is warning members to be prepared for longer waits at larger airports, as their towers may have fewer controllers on hand to handle traffic.

NBAA notes it has received questions from companies that must use airports with control towers for insurance purposes. The association advises that even if a tower remains open, operators should check whether its hours have been curtailed.

NBAA also warns that other services, such as government waivers for international travel, may take longer. “One likely impact will be reductions in staff available for processing waiver requests, various approvals from the FAA’s Flight Standards District Offices, Customs inspections and paperwork, and other government functions,” the association says.

FAA has also warned of anticipated delays in other services, such as certification.

FAA has not yet sent out furlough letters, nor finalized the list of towers. The agency last month released a list of potential towers that would close, and an FAA spokeswoman says the agency anticipates that most of those towers will be closed barring any change in sequestration. FAA hopes to have more details later this week.