Nine-year-old cousins Rose Powell and Flame Brewer soared into the skies above Rendcomb airfield in Gloucestershire, England, on Wednesday in an attempt to become the world's youngest formation wing-walkers.
The girls were strapped onto two vintage Boeing Stearman biplanes as they flew to heights of 500 feet at up to 100 m.p.h., NBC News reported.
The girls' grandfather, Vic Norman, flew Rose's plane while Martyn Carrington, director of flying at Aerosuperbatics, was at the controls of Flame's aircraft.
Rose, who said her cousin came up with the idea, described the flight as a "once in a lifetime experience," BBC said.
"It's quite scary when you take off but if you like mega funfair rides I think you'll find the takeoff really cool," she said.
"The best bit was probably taking off or doing the Superwoman pose."
Flame added that, "It was really fun and really windy. The best bit is just being in the air."
Flame's brother, Tiger, became the world's youngest wing-walker in 2009 at the age of eight.
Rose and Flame are now part of the third generation of their families to wing-walk on their grandfather's planes, The Guardian said.
They decided to follow a family tradition to raise money for their friend Eli Crossley, who has Duchenne muscular dystrophy.
The six-year-old's parents started the Duchenne Children's Trust in order to raise money to find a treatment or cure in time to save his life.
The girls are now waiting to hear from Guinness Book of World Records officials, who will verify their attempt at being the youngest formation wing-walkers before the record is entered into the books.
More from GlobalPost: Wing walker Jane Wicker killed after airshow crash in Dayton