If you’re trying to make sense of the FAA’s new MOSAIC rules—especially the way they impact “sport pilot” flying privileges—this post unpacks an interesting nuance. Even if you aren’t a certificated pilot, you’ll get value from understanding how technical limits shape which planes can be flown by a particular pilot.
The Basics: What Is “Stall Speed” and Why Does It Matter?
Every airplane has a stall speed—the slowest speed at which it can maintain controlled, level flight before the wings stop producing lift. This speed is measured in a couple of ways:
- VS1 (“clean” configuration): Stall speed with the aircraft in its normal, flaps-up state.
- VS0 (“landing” configuration): Stall speed with flaps and gear down, ready to land.
Why does this nuance matter? Because how you define stall speed affects which planes are available under MOSAIC for different types of pilots.
The Two MOSAIC Stall Speed Limits
The FAA’s new MOSAIC regulation creates 2 different stall speed thresholds:
- Aircraft Certification (Light-Sport Category): To be certified as a light-sport airplane, the plane’s VS0 (landing configuration stall speed) must not exceed 61 knots.
- Pilot Privilege (Sport Pilot Certificate): For someone flying with only a sport pilot certificate, the aircraft’s VS1 (clean stall speed) must not exceed 59 knots (as originally certified by the manufacturer—not after modifications).
Why Are There Two Numbers?
- VS1 is always higher than VS0 for any plane with flaps—meaning you can have an airplane with a VS0 under 61kt but a VS1 just over 59kt.
- This happens because flaps and other lift-enhancing devices used during landing lower the stall speed, making VS0 lower than VS1.
Here’s where things get interesting:
- Some airplanes, like the Cessna 182, have a VS1 below 59kt (for example, VS1 of 58kt), which fits the MOSAIC rule, even though they’re traditional, relatively heavy, four-seat general aviation planes.
- But there are also high-performance airplanes that qualify as “light-sport” under the 61kt VS0 limit, but their VS1 exceeds the 59kt limit.
The upshot?
There now exists a set of aircraft that are legal to be flown under “sport pilot privileges” if you have a higher-level license (private, commercial, ATP) … but are not legal for true sport pilots to operate, because their VS1 is over the limit. In other words, the category of airplane and the category of pilot don’t always match.
Why Did the FAA Do This?
The FAA set the VS1 for sport pilots lower as a matter of safety, noting that sport pilots receive less training than private pilots. The agency wanted sport pilots limited to slower, lighter, less complex airplanes. However, it used the more generous VS0 for certifying which new aircraft can be built/sold as light-sport, aiming to allow technological advancement and more capable planes into the market1.
What Does It Mean for Aviation?
- Expanded Aircraft Options: More new and legacy aircraft types can be built, bought, or flown as light-sport, making aviation more accessible and affordable for many people.
- Pilot-Paperwork Complexity: Someone with a private pilot certificate may operate certain higher-performance light-sport airplanes under sport pilot medical/self-certification rules. But sport pilots themselves have a stricter operational aircraft speed limit.
- Technical but Important: This is a prime example of how FAA regulations—a blend of engineering, safety, and policy—can create unique situations most people outside the cockpit never imagine.
In summary:
The new MOSAIC rules mean that some airplanes qualify as “light-sport” by one measure but not by another. As a result, there’s a set of airplanes that higher-certificated pilots can fly using sport pilot privileges, but which are out of reach for basic sport pilots. This quirky overlap demonstrates how the details of aircraft and pilot certification can have real, if nuanced, effects on who gets to fly what aircraft in the U.S. skies.