With the Boston bombings fresh on her mind, Cathy Critser of Summerville said she was terrified when a small plane swooped over her while she was driving on the Arthur Ravenel Jr. Bridge.

She called 911.

“It literally scared me to death. I couldn't hardly keep my foot on the gas pedal,” she said.

The Federal Aviation Administration said Thursday it will look into what happened Wednesday when a Charleston County contractor conducted aerial spraying for mosquitoes on both sides of the bridge.

“The FAA's inquiry will determine whether any federal air safety regulations were violated during the flights,” the agency said.

Ted Childress of Awendaw said the plane was 100 feet above the bridge deck when he saw it while traveling in the northbound lanes. The aircraft did a “half-turn and dive roll,” he said, maneuvers he compared to an air show. He pulled out a pocket camera and began recording the event.

“I thought maybe it was going to crash,” he said.

The county contractor, Williamsburg Air, was conducting a standard flight for mosquito control near the Ravenel Bridge, the county said.

“The plane was operating within the FAA guidelines, which enable us to exist in a restricted category so we can fly low to treat mosquito larvae,” the county said.

Critser said the plane came toward her from the downriver side of the bridge as she was traveling northbound from Charleston before reaching the towering overhead support cables. She thought the aircraft would hit bridge highway lights. Drivers were pulling over and stopping on the span because of the plane, she said.

“This plane looked like it was coming right at us,” she said.

Critser said that after the plane passed over the bridge, the pilot headed toward a tree line, which Critser thought the plane might hit. The incident happened at about 3:30 p.m., she said.

Guy McClary, owner of Williamsburg Air, said no one was in danger because of the aerial spraying operation at the bridge, which has happened twice before this year without complaint.

“Everything that's going on in this country, I can understand people being concerned,” McClary said.

He said the plane was 300 feet above the bridge.

“We're high enough across that bridge,” he said.

Williamsburg Air has contracted with the county for aerial mosquito control for seven years, he said.

The plane was near the bridge while treating both ends of Drum Island, a spoil area that is a notorious breeding ground for mosquitoes, the county said.

“It's important to emphasize that the pilot was not doing a 'fly-by' over the bridge, but was following normal protocol within our safety guidelines in order to conduct targeted mosquito treatment,” the county said.

Under protocol, the county notifies police in advance that such a plane will be in their area.

“This is all part of a very detailed and routine process to keep the mosquito population in Charleston County under control,” the county said.

Reach Prentiss Findlay at 937-5711.