When Susan Larson packed for her four-day, 2,600-mile competition in the all-female Air Race Classic, she deliberately packed just one sock.

Her feet get cold while flying her single-engine Cessna named Mikey, but packing two socks seemed frivolous – even unwise.

In air racing, socks mean weight, extra weight means extra seconds, and races are won in seconds.

Larson and her co-pilot, Amy Ecclesine, both from Santa Fe, N.M., are part of an annual competition nicknamed the Powder Puff Derby, with roots going back all the way to 1929 and aviation pioneer Amelia Earhart.

This year’s version of the race began Tuesday morning in Oklahoma City and is pegged to end today in Saint John, New Brunswick. Bangor was the next-to-last stop.

The teams fly small general aviation aircraft like Larson’s Cessna and must abide by visual, not instrument, flight rules. That means flying during daylight hours only, and no flying in the clouds.

The race is handicapped because pilots have various types of aircraft and horsepower engines. The pilots are essentially racing against their own handicap, and the first to cross the finish line is not necessarily the winner, Larson said.

Larson, who declined to give her age, is also a helicopter pilot. She owns a company in New Mexico that offers aerial tours and provides transportation to movie companies doing location filming.

Her co-pilot, Ecclesine, 51, is a project manager for Los Alamos National Laboratory in New Mexico.

After landing at Bangor International Airport at mid-day Thursday, Larson and Ecclesine taxied to the private aviation service Avitat Bangor and finalized flight plans before breaking for lunch and a layover.

Larson said she had packed only one sock for the four-day trek because, after all, the bare foot absorbs heat when next to its better-garbed partner.

As Larson explained her wardrobe, Ecclesine could not help but chuckle. “This is why I’m out here,” Ecclesine said. The pilots spend numerous hours together during the derby, and brief layovers provide the only alone time.

Ecclesine had spent close to 30 minutes using Pledge to wipe away the oil residue that had collected at the bottom of the plane, while Larson went inside to file flight plans and check weather reports.

“This is my meditation at every stop,” Ecclesine said from her seated position under the red and white Cessna 182.

Approximately 45 racing teams were still competing Thursday, but that number can change quickly, Ecclesine said.

Racers must stop at eight predetermined airports along the way, and the flight route brought all the pilots to Maine for the first time in race history.

Some racers will stay the night in Bangor.

“A lot of people look at aviation as a male-dominated profession, but aviation is alive and well amongst women pilots and the proof has been going on for 31 years,” said Kevin Kipler, a manager at Avitat Bangor. The race has been operating under its current name for 31 years.

The race is all about strategy, luck and even patience, a virtue Ecclesine still needs to learn, Larson said.

Ecclesine competes in triathlons, but this is her first air derby. And the breaks between air race checkpoints are laborious.

“I’m a racer. I like to race,” Ecclesine said. “I just want to be there already.”

Larson, who is vice president of The Ninety-Nines International Organization of Women Pilots, recognizes her co-pilot’s competitive edge.

“I sometimes need to reign her in, like a very spirited horse,” Larson said.

Weather patterns prevented the women from taking off again Thursday afternoon.

Larson saw the weather as the perfect excuse to escape from the airport and indulge in their first meal since the previous day. The two made their way to the Sea Dog Brewing Co., determined to find a Maine lobster roll.

Twenty minutes and half a glass of red wine later, Larson received a cell phone call saying weather patterns had changed and that some of the other pilots had decided to head off to New Brunswick.

Even if she had not drunk wine over lunch, Larson said, she still would have saved the last leg of the race for today.

“If you know the rules, you play the game and you must always fly your own race, follow your own flight plan,” Larson said after hanging up the phone.

The pilots had packed only trail mix, cheese, dark chocolate espresso beans and protein bars – all relatively light in weight – and the lobster rolls were a shock to the taste buds. In New Mexico, lobster meat is served in a tortilla rather than a hot dog roll, Ecclesine said.

After checking weather reports on Thursday afternoon, the two were excited to learn they might be able to sleep in – at least until 6 a.m. They have been getting up around 4 a.m. much of the week.

“The race is not for the faint of heart, weak of constitution or lacking of the stomach,” she said.