HILLSBORO, N.D. — His target just out of sight, Kent Ridl leaned into the left turn until his plane found itself once again on a straight course.
“There it is,” said co-pilot Ken Schuler, whose eyes hadn’t left the quarry during the turn. “Keep coming, keep coming, keep coming.”
A few hundred feet ahead and above their position flew an unmanned aircraft busy photographing the sprawling farmland below them. The pair had one mission: keep the aircraft in their sights at all time.
“It’s a position game all day long,” Schuler said.
The game of cat and mouse taking place thousands of feet above the heads of Traill County residents is part of a North Dakota State University research project that aims to analyze imagery of crops taken as various altitudes.
The project requires the use of a Hermes 450, a nearly 1,000-pound, high-altitude unmanned aircraft. Federal law prohibits flying unmanned aircraft beyond the line of visual sight so those involved in the research project needed to get creative.
That’s where Ridl, Schuler and other members of the North Dakota wing of the Civil Air Patrol have come into the picture over the past weeks. During research operations, patrol volunteers fly chase planes which do exactly as their name suggests — tail the drone in flight.
The use of chase planes allows researchers fulfill federal requirements while flying the drone thousands of feet off the ground.
Researchers with NDSU and the Northern Plains UAS Test Site are receiving assistance from the American arm of the Israeli drone’s manufacturer, Elbit Systems, during the project.
Eye in the sky
Tracking an airborne drone isn’t the easiest feat. Two people are required in the cockpit of the chase plane, one to pilot the aircraft and one to act as the visual observer.
As the plane follows the Hermes through turns, the plane wings can block the pilot’s view, which leaves the visual observer to keep it in sight.
“There’s definitely an art to it,” Schuler said. “You get a workout mentally and physically because you’re constantly looking and communicating between the two of you.”
A plane has followed the drone throughout the summer as it photographs a 4-mile wide by 40-mile long corridor of farmland stretching through Steele and Traill counties.
During flights, the pilot and observer also monitor air traffic control channels and listen to chatter as the drone pilot relays his next move or staff at Hector International Airport in Fargo inform them of nearby aircraft.
The surrounding sky can throw in a monkey wrench now and then. During their July 15 flight, Ridl and Schuler started out with a clear sky that slowly filled with clouds as the day progressed.
The Hermes kept clear of most clouds but the chase plane flew about 500 feet below it, putting it level with clouds that obscure the observer and pilot’s views.
“We have to maneuver to stay in view but maneuver to stay out of the clouds,” Ridl said.
Civil Air Patrol volunteers typically fly twice a day for four or five hours at a time if conditions permit.
The flights typically run two days at a time but a five-day week is built in to allow for weather delays, such as the days of rain leading up to the July 15 flight.
Bill Kay, deputy chief of staff of the patrol’s north central region, lives 245 miles away in Minot and spent those rainy days holed up in a hotel waiting to fly.
Kay, Ridl and Schuler are three of 284 volunteers that are part of the North Dakota wing, which is part of a larger congressionally chartered nonprofit that provides emergency services, aerospace education and a cadet program. The organization also assists other groups with missions, such as the Hillsboro research project.
Schuler and Kay have flown similar chase plane missions before in other parts of the state, but the July 15 flight marked Ridl’s first time out on such a mission. The clouds ultimately ended the workday early, but Ridl did gain valuable experience for future flights.
“The other really big challenge, this my first time doing it, is when they have those little bits where they fly really slow and you can only go so slow in a plane,” he said. “It’s tricky to get back behind them again.”
The July 15 flight knocked about three hours of a total 12 hours researchers hoped to complete for the month. The project will require the Hermes to fly at three different altitudes ranging from 4,000 to 6,000 to 8,000 feet above ground. Pictures taken during those flights will be compared to imagery captured by satellite and smaller drones.