ROCKLAND – Complying with some proposed federal aviation safety regulations could cost Knox County and its airport more than $400,000 a year, in addition to startup costs of nearly $500,000, county officials have calculated.

The new Federal Aviation Administration regulations would require airports that have passenger flights on aircraft with 10 to 30 seats to comply with the same fire suppression standards that larger airports meet.

The change would affect three airports in Maine: Knox County Regional Airport in Owls Head; Hancock County-Bar Harbor Airport in Trenton; and Augusta Airport.

If the rules take effect, airport officials would have to show FAA inspectors that they could get a firetruck on a runway within three minutes of an alarm.

The proposed rules were not inspired by the Sept. 11, 2001, terrorist attacks, but rather by a deadly crash in the Midwest in which a plane burned on a runway.

If Congress does not act to change them, the rules go into effect in three years.

The state Department of Transportation requested that operators of the three airports review the cost of complying, then send the estimates to the state. At their meeting Tuesday, Knox County commissioners signed a letter showing cost estimates and agreed to send it to DOT.

The letter addressed to DOT’s Jennifer O’Bryon estimates startup capital costs of $471,000 and annual operational costs of $412,725.

On Wednesday O’Bryon said she had not yet received estimates from the other two airports. Most of the annual costs involve $372,725 for salary and benefits for six firefighters who also would be trained as emergency responders. The county anticipates three working a Monday-through-Friday shift, and three working Saturdays and Sundays.

Commissioner Anne Beebe-Center conceded that some of these costs might be reduced with the help of area volunteer firefighters.

An additional $20,000 would be spent annually to train and equip the staff, according to the county. Fuel, oil and repair costs for the firefighting vehicle are expected to be about $10,000 each year.

The capital costs are:

. $150,000 for a building to house the fire vehicle.

. $30,000 to train and equip personnel.

. $10,000 for marking, signs and lights.

. $15,000 for two copies of an airport certification manual.

. $6,000 for emergency access roads.

. $10,000 to develop an emergency plan.

. $30,000 for two-way radio.

“Even if FAA and MDOT agreed to participate in purchasing and improving capital items, Knox County would have to front the costs before reimbursement would be forthcoming and would have to contribute nearly $24,000 for the capital items,” the county letter says.

The commissioners concluded that it would be “impossible to ask the citizens of Knox County to absorb these annual costs that will only escalate year to year.”

The estimates were developed by the airport’s maintenance supervisor, the operations and planning coordinator, and the county clerk-executive assistant.