Suspicious aircraft alerts in the area may be more frequent than residents realize.

On Thursday, the U.S. Department of Homeland Security called the Dickinson Theodore Roosevelt Regional Airport to alert them of a plane that pinged on their radar, said Matthew Remynse, airport manager. The plane never landed there, he added.

They wanted to know if the plane had landed here and they called the sheriff's department, Remynse said. "That's where we leave it. Homeland Security really doesn't give out information on why they're looking at this plane or anything like that."

The airport has emergency and security plans if a suspicious plane should land, but Remynse said he couldn't discuss such plans.

"It's sensitive security information," Remynse said.

Customs and Border Protection could not release specific information about the incident, said Jim Knoell, director of air operations for the North Dakota Air Branch Office of Air and Marine in Grand Forks.

Typically, a call like the one made to the Dickinson Airport is in regards to a plane that came across the Canadian border, Knoell said.

"To fly in from Canada you have to have a flight plan and the U.S. authorities have to know you're coming and where you're going to be landing to be inspected," Knoell said. "So, if a random plane came from Canada, or was thought to have come from Canada and crossed the border without permission, then that would definitely bring suspicion up."

When the Stark County Sheriff's Department receives a call like this, officers wait in the airport parking lot for the plane to land, Capt. Lawrence Kitzman said.

"There's the potential for drug trafficking, illegal alien trafficking or any other criminal activity," he said.

"We'd identify the pilot, get his pilot license number, get the tail number off the airplane and detain him and all passengers and notify customs and they'd come check him out," Kitzman said.

A plane hasn't had to be detained at the airport.

Knoell said if such a plane landed, it would be detained and the situation would regulate what CBP would do next.

"They would be interviewed by authorities, that's for sure, to find out what was going on," Knoell said.

J.B Lindquist, Hettinger Municipal Airport manager, said Homeland Security called him as well on Thursday. He added a suspicious plane did not land there either.

"There was nothing said to us as to whether we should hold the airplane, you see, or anything like that," Lindquist said.

The alerts like what happened Thursday don't appear to be a rarity.

"If I would put a frequency on it, I would say in the last six months, maybe we've had three of those phone calls," Lindquist said.

Remynse said in nearly four years he has received three phone calls from Homeland Security.

Managers at Bowman and Mott airports said they have never received phone calls for suspicious aircraft and didn't receive a call Thursday.

Knoell said statistics of how often aircraft pique their interest were not available Tuesday.

It's unclear where the aircraft in question went.

"They have no idea what it looks like, because they just have it on radar," Remynse said. "Basically, they said it's headed toward your airport, if it lands, this is what needs to happen, and it didn't land."

Kitzman said the department is never told what becomes of suspicious planes, either. However, he said they are likely often farmers who got too close to the border.