DUBUQUE, Iowa (AP) — Cruising in the air at 8,000 feet, Ken Blackburn inspected his flight plan over the rumble of the engine.

As he pored over radio frequencies, navigation beacons and weather data, the airplane’s altitude slowly drifted upward, a happening that would not go unnoticed by air traffic controllers.

“Whoops,” Blackburn said, grinning. “You get 50 feet before you get a bad-boy mark.”

He lowered his pitch and scanned the horizon. On Independence Day weekend, he would be an angel, and his Piper Archer II airplane, his wings.

Departing Dubuque for Fargo, N.D., Blackburn spent the holiday transporting donated blood samples on behalf of Angel Flight Central, a nonprofit organization that organizes charitable flights.

At 77 years old, Blackburn’s hair is thinning and brown spots dot his arms. But behind his wire-rimmed glasses are decades of piloting experience and a love for the skies.

“It gets in your blood,” he told the Dubuque Telegraph Herald.

Blackburn traces his interest in flight to his childhood, where one of his father’s friends took him for rides through the Adirondack Mountains in upstate New York.

A seed took root in the then-5-year-old. In school, he studied electrical engineering and spent much of his career designing hardware that was used in the radar systems of military aircraft.

Blackburn’s hero was the American fighter pilot Bob Hoover, who was shot down during WWII and held in a German POW camp. He later escaped by stealing an enemy aircraft and continued to fly for nearly 50 years.

Although Blackburn did not serve in the military directly, he jokes that he designed the U.S. to victory during the Cold War.

Blackburn began flying in the 1970s and enjoyed traveling with his two children and wife on family vacations. With his retirement in 2009, he had more time to fly but was running out of places to go.

Angel Flight Central, for which he began volunteering in 2006, gave him a new list of destinations he never would have considered.

Blackburn’s morning run out of Dubuque took him north past Cassville, Wis., and Guttenberg, Iowa.

The plane shook as it climbed. Below, trees took on the appearance of broccoli tops, while barges snaked their way along the Mississippi River, which glowed in the sun.

“Listen to the bloody engine roar!” Blackburn said. “We have oil pressure. Things are looking good.”

The 90-minute flight continued to southeast Minnesota where he landed at an airstrip in the City of Faribault to eat lunch and refuel.

Blackburn’s aircraft, manufactured in the 1970s, runs on a single propeller. It cruises at 130 miles per hour with a range of about four hours of flying time.

It might lack the amenities of a newer airplane, such as vertical autopilot controls, but Blackburn proves they aren’t necessary.

Even though he has installed a new radio system, he remains in a perpetual competition with the navigational software on his iPad.

After takeoff, he grabbed his “whiz wheel,” a circular slide rule that can calculate flight distance and time of arrival.

The computer predicted a 1:16 p.m. arrival, while Blackburn calculated 1:27 p.m.

“We disagree again,” he said, chuckling.

Flying an aged aircraft requires a flare for multitasking.

Blackburn adjusted dials on his instrument control panel, inputting air temperature and pressure readings. Then, he consulted flight maps to identify navigation beacons and local airstrips that might become his salvation in the event he needed to make an emergency landing.

Nearly 5,100 airports are open for public use across the U.S., but Blackburn might have to opt for a lake or river if he cannot spot one nearby.

“Water is a lot softer than ground,” he said.

Every weekend, Angel Flight Central pilots descend into the Hector International Airport in Fargo to fetch blood samples from Vitalant, a community blood provider.

They courier the cargo to a St. Louis blood testing laboratory. Most important are the platelets, which have a three-day shelf life. As soon as they are tested, the donations can be distributed to cancer patients.

But Angel Flight Central volunteers also transport patients who lack the financial means to travel to medical appointments. Sometimes, their doctors could be located several states away.

“Our goal is to help out as many people as we can,” said Don Sumple, the Kansas City, Mo., nonprofit organization’s executive director. Angel Flight Central covers a 10-state region, which includes Iowa, Illinois and Wisconsin.

More than 325 pilots volunteer their time, and in 2019 Angel Flight Central coordinated nearly 2,550 flights.

In addition to low-income passengers, Angel Flight Central routinely transports cargo, a trend that increased with the onset of the COVID-19 pandemic when commercial airliners cut back their scheduled flights.

Volunteers, who fly at their own cost, have ferried generators and supplies following hurricane strikes on U.S. coastlines and personal protective equipment to rural hospitals.

Nearly every day of the year, an Angel Flight Central pilot is in the sky.

Blackburn spends hours preparing, especially for complex operations that involve multiple legs.

The night before his return to Dubuque, he filed paperwork with the Federal Aviation Administration over a plate of sticky barbecue ribs at the NoBull Smokehouse and Bar in downtown Fargo.

Blackburn crossed himself and silently said grace before digging into his corn casserole.

His greatest preoccupation is the weather. The local forecaster is a good source, but he also verifies the data with the National Oceanic and Atmospheric Administration.

Flying through a thunderstorm can doom an aircraft, exposing it to downdrafts, hail and lightning.

“They’re killers,” Blackburn said.

The next day, he readied his plane at the Fargo Jet Center. He checked his plane’s oil, then his watch, awaiting the arrival of the cargo — the reason he came to North Dakota.

A van with a bright orange and purple Vitalant logo pulled up to the building. Mikki Kjelvik walked across the tarmac, lugging a bulky red box.

“Thank you for doing this on your holiday,” she said, handing Blackburn the insulated package, which was filled with dozens of tubes.

He buckled it up on the backseat.

Taking off, Blackburn aligned the plane on a direct route to Fort Dodge, Iowa.

Cessna pilot Dan Silvers met him on the ground, where Blackburn handed off the package. Silvers would complete the remainder of the nearly 700-mile journey.

The 35-year-old web developer has been volunteering for Angel Flight Central for more than two years and lately has been making runs every weekend.

“It’s just another reason to fly,” he said.

When Blackburn turns 80, Angel Flight Central will require him to fly with a younger safety pilot on board as part of a two-person crew. He grumbled at that prospect.

A pilot knows when he should stop taking to the skies, Blackburn said.

“In life, we are supposed to help other people,” he said. “When I get to the pearly gates, St. Peter’s probably going to ask me what did you do for me, you know?”

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