A CubCrafters Carbon Cub UL climbed to a verified altitude of 37,609 feet above sea level over the California coast on Oct. 28, 2025, setting an unofficial new world altitude record for Cub-type aircraft.
This historic climb surpasses the previous record of 30,203 feet set by pioneering aviator Caro Bayley in a PA-18 Piper Super Cub over Miami in February 1951, according to CubCrafters’ officials. Bayley’s record was recognized internationally by the Fédération Aéronautique Internationale (FAI) in the C-1b light-aircraft class, earning her the Blériot Medal, and has stood the test of time as the high-altitude benchmark for light STOL aircraft for almost 75 years.
Mission to Reach New Heights
Although not an official FAI record attempt, the Rotax 916 iS-powered Carbon Cub UL also surpassed the current official FAI Ultralight category world record altitude of 35,062 feet, which has been held by a Rutan Long EZ since 1996, according to CubCrafters officials.
Piloted by Jon Kotwicki, the Carbon Cub UL began its climb at 9:55 a.m. out of the San Luis Obispo Airport (KSBP) under ideal weather conditions and with approvals from Los Angeles ARTCC. The aircraft reached its peak altitude of 37,609 feet after approximately 62 minutes of climbing, with an outside air temperature of -51°F/ -46°C.
This project was a team effort, CubCrafters officials noted.
The turbocharged Rotax 916 iS engine was developed by Rotax in collaboration with CubCrafters and Rotax served as a technical advisor on the project. At extreme altitudes, Kotwicki relied on supplemental oxygen supplied by project partner Mountain High Equipment & Supply and wore a parachute as a precaution.
Despite thin air and extreme cold, the aircraft maintained remarkable stability and control throughout the flight, according to Kotwicki.
“The Cub flew really easy,” he said. “We were outside the normal realm of operating parameters, so we were proceeding with caution. It was pretty dang cool to be in a tube-and-fabric bush plane that high, and it was surreal hearing airline pilots over ATC wondering what a Cub was doing up there.”
The team’s goal was to reach 30,200 feet to break the record for a Cub-style airplane, but with the perfect conditions, Kotwicki continued to 37,609 feet.
“We didn’t know how high we could go, and we were honestly surprised we reached that altitude with 29-inch Alaska Bushwheels installed and all the camera gear onboard,” Kotwicki said. “The UL is truly an amazing backcountry aircraft. We could have gone directly from over 37,000 feet to landing and taking off from any unimproved dirt strip anywhere in California. That’s what makes this machine so versatile.”
“This is my 17th aviation record, and it was one of the most fun to go after,” said Paulo Iscold, a professor in Cal Poly’s Aerospace Engineering program and Project Manager for the record attempt. “The entire team was great to work with. From CubCrafters and Rotax to Aerocrafted and Mountain High, we couldn’t have asked for better partners or a better aircraft for this project.”
“In test flying we plan for everything to go wrong,” he continued. “When everything goes right — that’s the flight you wanted, that’s the flight we got.”
For more information: CubCrafters.com
What was your indicated airspeed and true air speed?
If you look at the Garmin display you will see 113 Kts TAS, 61 kts IAS and 127 Kts GS.
What a great accomplishment..!! -51D/F in a tube & rag aircraft… WOW
ATC, and Airline pilots wondering what a cub was doing up there is hilarious. Reminded me of Lawnchair Larry, riding a lawn chair tied to helium balloons in 1982 to 16,000 ft over Los Angeles.