As airline pilots on frequency marveled at the achievement, a Rotax-powered CubCrafters Carbon Cub set a new light-aircraft altitude record, climbing to 37,609 feet over California on October 28, 2025, and surpassing a benchmark that had stood for 75 years.
The flight, which some social-media users initially dismissed as an AI-generated spoof, has been verified by FlightAware data and confirmed by CubCrafters. It occurred with special FAA approval and coordination from the Los Angeles Air Route Traffic Control Center (ARTCC).
The remarkable achievement — a climb to 37,609 feet in a factory-stock Carbon Cub UL — was made by flight instructor and YouTuber Jon Kotwicki, who launched from San Luis Obispo Airport (SBP) and reached the record altitude in 62 minutes.
The flight was supported by CubCrafters and Rotax, whose team developed the turbocharged 916iS engine installed in the Carbon Cub UL. The aircraft, according to both companies, was completely factory-stock and fitted with large bush wheels and camera equipment, making the feat all the more noteworthy.
The performance shattered the 30,203-foot record set in 1951 by Caro Bayley in a Piper Super Cub, which had stood unbroken since 1951. It also appears to surpass the ultralight-category altitude record of 35,062 feet, set by a Rutan Long-EZ in 1996. At 37,609 feet — more than seven miles high and well above the summit of Mount Everest — Kotwicki encountered temperatures of –51°F and wore a parachute along with supplemental oxygen.
FAA coordination and airspace considerations
Operating above FL290 placed the Carbon Cub well inside RVSM (Reduced Vertical Separation Minimum) airspace, where altitude separation between aircraft is just 1,000 feet and special equipment is required. Normally, only aircraft with those systems and operator approval can enter that airspace. However, because Kotwicki’s record attempt was pre-coordinated with the FAA, the flight was conducted safely under ATC supervision, with controllers ensuring separation from other traffic as the aircraft climbed and descended through the flight levels.
Despite thin air and extreme cold, the aircraft maintained remarkable stability and control throughout the climb. “The Cub flew really easy,” Kotwicki 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 Carbon Cub UL is not RVSM-certified and is designed primarily for visual flight rules (VFR) operations. That meant Kotwicki was required to remain clear of clouds throughout the climb. While the day offered ideal visibility, the high altitude introduced unique challenges — frigid temperatures, limited engine performance even with turbocharging, and the physiological risks of hypoxia.
Technical achievement
The Rotax 916iS, producing up to 160 hp, combined with the Carbon Cub’s exceptionally light structure and high-lift wing, allowed the aircraft to maintain climb performance far beyond its typical service ceiling. Some pilots suggested mountain-wave lift over California’s coastal ranges may also have contributed to the record altitude.
CubCrafters and Rotax both confirmed their technical support but emphasized that the aircraft was unmodified. The climb was part of a collaborative effort between the manufacturer and Kotwicki’s training organization, Fly8MA, to explore high-altitude performance.
“This achievement exemplified 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, our founder, was to take the Super Cub — 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.”
The Fédération Aéronautique Internationale (FAI) has not yet officially recognized the record, but based on altitude data and witness verification, the flight appears to qualify within the ultralight or experimental light-sport categories.
If certified, the flight will stand as the highest altitude ever achieved by a Cub-type aircraft and one of the most remarkable climbs by any light airplane. For Kotwicki, the flight fused modern engine technology with a classic airframe and a pilot’s instinct to explore the limits of what’s possible.
