Demonstrating the power of modern backcountry aircraft, a CubCrafters Carbon Cub UL soared to a verified 37,609 feet (11,460 meters / 7.12 miles) over the California coast on October 28, 2025, setting an unofficial world altitude record for Cub-type planes.

The engine was running at full power, turning 5,826 rpm with 23.2 inches of manifold pressure, when the aircraft reached a pressure altitude of 35,720 feet and an airspeed of 61 knots (113 knots true airspeed).

The historic flight, conducted over the California coast, surpassed the previous record of 30,203 feet set by pioneering aviator Caro Bayley in a PA-18 Piper Super Cub over Miami, Florida, in February 1951.

Bayley’s achievement was internationally recognised by the Fédération Aéronautique Internationale (FAI) in the C-1b light-aircraft class and earned her the prestigious Blériot Medal. For nearly 75 years, her record has served as the high-altitude benchmark for light STOL aircraft.

A Mission Decades in the Making

The Carbon Cub UL represents the latest evolution in CubCrafters’ ongoing mission to build the highest-performing backcountry aircraft available.

The record-setting climb showcased cutting-edge engineering focused on exceptional power-to-weight ratios, modern powerplants, and superior efficiency—all while maintaining the aircraft in a typical bush plane configuration that has made Cubs legendary in the aviation community.

“This achievement exemplifies everything we stand for — innovation, craftsmanship, and the courage to push limits,” said Brad Damm, Vice President of CubCrafters.

“The original vision of Jim Richmond, the founder of CubCrafters, was to take the Super Cub, considered the workhorse of backcountry aviation, and make it better. I think Jim would be the first to congratulate our team on what was achieved on this flight.”

While not conducted as an official FAI record attempt, the Rotax 916 iS powered Carbon Cub UL also easily 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.

The Record Flight

Piloted by Jon Kotwicki, the Carbon Cub UL departed San Luis Obispo Airport (KSBP) at 9:55 a.m. under ideal weather conditions and with full approvals from Los Angeles Air Route Traffic Control Center (ARTCC).

The aircraft reached its peak altitude of 37,609 feet—equivalent to 11,460 meters or 7.12 miles—after approximately 62 minutes of steady climbing. At that extreme altitude, the outside air temperature registered -51°F (-46°C).

The ambitious project required extensive collaboration and technical expertise. The turbocharged Rotax 916 iS engine was developed by Rotax in partnership with CubCrafters, and Rotax served as a technical advisor throughout the project.

At extreme altitudes where the air is dangerously thin, Kotwicki relied on supplemental oxygen supplied by project partner Mountain High Equipment & Supply. As a safety precaution due to the unprecedented nature of the flight, he also wore a parachute.

Despite the thin air and extreme cold at altitude, the aircraft maintained remarkable stability and control throughout the entire flight profile.

“The Cub flew really easy,” Kotwicki reported after landing. “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.”

Beyond Expectations

The team’s initial goal was to reach 30,200 feet—just enough to break the long-standing record for a Cub-style airplane. However, with perfect conditions aligning, Kotwicki made the decision to continue climbing to 37,609 feet, pushing the boundaries of what the team thought possible.

“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 explained.

“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.”

The statement underscores the unique nature of the achievement—this wasn’t a purpose-built record aircraft stripped of all useful equipment. This was a fully capable bush plane that could transition from the edge of the stratosphere to a remote mountain airstrip without modification.

Team Collaboration and Expertise

Paulo Iscold, Professor in Cal Poly San Luis Obispo’s Aerospace Engineering program and Project Manager for the record attempt, brought extensive experience to the endeavor.

“This is my 17th aviation record, and it was one of the most fun to go after,” Iscold said.

“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.”

Reflecting on the successful outcome, Iscold noted: “In test flying we plan for everything to go wrong. When everything goes right — that’s the flight you wanted, that’s the flight we got.”

The team behind the record-breaking flight included Tres Clements from Aerocrafted, who provided hangar facilities, tools, and ground support; Kotwicki from Fly8MA as pilot; and Iscold providing project oversight and management