MOSAIC Four-Seaters

Most of the talk about the new generation of “MOSAIC LSAs” focuses on speedy two-seaters, most of them with retractable gear: Sparker, Stream, Shark, Risen, Tarragon, Blackwing, Blackshape, Wasatch …

However, don’t forget that MOSAIC allows larger airplanes to be certified via compliance with ASTM standards: airplanes with up to four seats, including twins. So, just as the original LSA regulations from 2005 led to the development of many new certificated two-seaters (such as the Van’s RV-12, Icon A5, and CubCrafters Carbon Cub SS, to name a few), it’s quite possible that some new four-seaters and twins will soon enter the market. The single-engine ones with clean stall speeds below 59 knots now can, of course, be flown without a medical certificate; this “feature” has already been an important factor behind the development and sales of LSAs for the past 20 years.

What new four-seaters might soon be certified as S-LSA via MOSAIC? Below is a list of the most likely candidates.

And one last bit of context before we jump in: Interestingly, Brazil passed its local version of MOSAIC in 2022. Most of the world knows that Brazil is a key player in the world of aviation thanks to Embraer’s jets, but most Americans probably do not realize that the South American country also has a significant impact in the general aviation market. For example, over 40% of flying RV-10s are registered in Brazil, almost as many as in the U.S. So, when Brazil opened the door for new four-seaters to be certified and sold in the country via compliance with ASTM standards rather than the much more onerous (i.e. expensive) Part 23 certification process, a few companies jumped on the opportunity … and those airplanes could soon be available in the U.S. as well, under MOSAIC.

Van’s RV-10

Photo: Van’s Aircraft

The first certified four-seater S-LSA in Brazil was the Van’s Aircraft RV-10. Builders of Van’s RVs know that the company offers “quickbuild” kits where 49% of the work has been done, a substantial fraction of the structural assembly of the wings and fuselage. Two companies do this quickbuild pre-assembly, one in the Philippines and one in Brazil. The one in Brazil, Flyer Indústria Aeronáutica, has been building ultralights and LSAs for decades, including some of its own design, as well as providing builder-assist services for RVs and other kit planes. So, when the regulations were about to change in Brazil, Flyer teamed up with Van’s to certify the RV-10 down there — not just the airplane, but also the factory, the suppliers, the fleet safety monitoring system, and so on. As of 2023, it is possible to buy a factory-built certified RV-10 in Brazil, and to use it commercially such as for flight instruction or rental. Not only that, but Flyer also certified an interesting new powerplant option: the SMA 305-230, a turbocharged diesel/Jet A piston engine already in use on some Cessna 182s. (In much of the world, the availability and cost of 100LL are significantly worse than in the U.S.) Yes, 230 hp may not sound like much for a 2,700-pound airplane, but thanks to the turbo, it makes more power than an IO-540 once you’re above a few thousand feet — and burns significantly less fuel, increasing the RV-10’s range and endurance by 20%. In addition, the fact that BRS offers an RV-10 retrofit kit means that the airplane is comparable to a Cirrus but for one-third the price. And a final interesting tidbit: Brazilian-built airplanes are exempt from U.S. import tariffs.

Photo: Sling Aircraft

Sling TSi

Similarly to Van’s Aircraft, South African company Sling Aircraft initially introduced a two-seat kit plane LSA that was quickly made available as a factory-built certified airplane when the original Light Sport rules came out in the U.S. … and then certified its four-seat kit plane in Brazil as soon as local regulations allowed: The Sling TSi four-seater S-LSA is now in production in a factory in Brazil. This is a smaller airplane than the RV-10, with a maximum weight of 2,095 pounds. However, it does have four seats, and its compact aerodynamics — and the Rotax 915 or 916 engine that powers it — make it exceptionally fuel-efficient. The turbo-normalized engines allow for surprisingly fast cruise up at altitude, roughly 150 knots at the altitudes where oxygen starts to be required. Finally, don’t forget that Rotax engines can use automotive gasoline, making the Sling TSi an exceptionally cost-efficient four-seater.

Montaer MC-04

Photo: Montaer

Moving away from kit planes for a second: Brazilian airplane company Montaer — developer of the MC-01 — has recently unveiled its new four-seater S-LSA, the MC-04. Most of the airplane’s numbers are similar to a 172, give or take: Maximum weight is 2,425 pounds, cruise around 130–132 knots … but powered by a Rotax 916 iS, allowing for high efficiency (especially at altitude) and low fuel costs. The empty airplane is remarkably lightweight, making the useful load an exceptional 1,235 pounds, a true four-seater. Can any other Rotax-powered airplane carry that much? New information is still coming out about this brand new design.

The RV-10, Sling TSi, and Montaer MC-04 have already been certified through ASTM standards, so their availability in the U.S. post-MOSAIC seems like a safe bet. The airplanes listed below … have not yet, but the manufacturers are working on it.

Veloce ANG

Photo: Veloce Planes

Pilots in the homebuilding world may be familiar with the KIS TR-1 two-seater and TR-4 four-seater. These low-wing composite kit planes were developed by Rich Trickel in the 1990s. The TR-4 Cruiser has been improved over time under various names, such as the Volato 400. The latest is the Veloce ANG, a substantial airplane that can weigh up to 2,786 pounds, with a useful load of over 1,400 pounds. Different versions can be powered by anything from the IO-360, IO-390, TIO-540 … up to the “AeroVolare,” a 300-hp Chevy LS conversion developed in-house by Veloce. Naturally, performance numbers will depend on the engine, but cruise speeds around 170–180 knots are claimed with the 300-hp AeroVolare. I am curious to see what engine will be in the first MOSAIC-certified factory-built ANGs.

Bushliner 1850

Photo: Bushliner Aircraft

Initially developed in Canada, the Bushliner 1850 Cyclone is essentially an improved Cessna 185. It is currently being offered as a factory-assisted amateur-built airplane, meaning that builders must assemble it at Bushliner’s facility, in Washington state. The size and performance of this airplane really take advantage of the new MOSAIC regulations: 2,000-pound useful load, 4,200-pound maximum gross weight, 350 hp, 140-gallon capacity … and the option for a diesel/Jet A engine (if and when DeltaHawk makes it available). The non-MOSAIC amateur-built version can even have six seats. The downsides: The Cyclone has been in development for many years, a very small number of them have been built, and it’s unclear whether the airplane is currently available since some modifications to the design were recently announced. Still, the performance numbers are certainly impressive, and the proven bush plane ruggedness is appealing.

Sport pilots cannot fly twin-engine airplanes. However, twin-engine airplanes can be certified as S-LSA under MOSAIC, far less expensively than via the traditional FAA certification process. This new possibility has led several companies to explore the development of new twins. Interestingly, the four examples listed below have all chosen the Rotax 916 iS as their powerplant.

ATP Aviation AT-6

Polish aeronautical engineer Tomasz Antoniewski designed and built his first airplane, the AT-1, as part of his graduate thesis in 1990. He founded Aero AT to develop and manufacture his subsequent creations, such as the AT-3, which is known in the U.S. as the Gobosh 700S. His latest design is the AT-6, which has been in work since 2012 and recently made its first flight. The striking-looking four-seater is aimed at the instrument and multi-engine training market, and targets the new MOSAIC regulations. Featuring both a T-tail and canards for stability and balance, it is reminiscent of the Piaggio Avanti — but with tractor propellers and all-metal construction. Cruise speed is estimated to be around 160 knots.

Photo: AT-P Aviation

Alpi 800 Pioneer

For over 10 years, Italian company Alpi Aviation has been producing its Alpi 400 four-seater. Much of the design was retained for its first twin, the Alpi 800 Pioneer, unveiled at Aero Friedrichshafen 2026. According to Alpi, the plan is to offer the airplane as a kit in Europe and to certify it for factory production under MOSAIC in the U.S.

Photo: Alpi Aviation

Sling Twin

Sling has also recently announced that it will develop a twin-engine airplane available both as a kit and ready-to-fly. This would be a larger airplane than the others on this list: Although the factory-built MOSAIC-certified version must be limited to four seats, the homebuilt variant may have up to six seats. Only computer-generated imagery has been released so far, but Sling hopes to have a prototype at EAA AirVenture 2027.

Rendering: Sling Aircraft

Skytron

Image: Skytron

Skytron is by far the most ambitious airplane on this list. I say this not because of its unusual configuration: a V-tail, and pusher engines on top of the wings like a HondaJet. The plan for this airplane is unique. It starts with how MOSAIC regulations mention reduced pilot-training requirements if automation and simplified controls are used. Skytron intends to push this to the limit, and then to demonstrate that the limit could be redefined even further. It hopes to develop an airplane that pretty much flies itself, from start-up to shutdown. The path toward that goal includes designing an airplane that adjusts all kinds of parameters (such as trim and engine settings) automatically, an airplane that cannot be stalled or spun or flown into terrain or into another aircraft, will not allow itself to run out of fuel before making an emergency landing, etc. In other words: an airplane whose automated systems can reliably keep the pilot out of trouble. Although experienced pilots may dislike the thought of such an authoritative machine, the fact is that much of pilot training focuses on avoiding certain dangerous possibilities … and maybe, just maybe, a very smart system could be designed to avoid them for us, or for some new pilots (“pilots”) who choose to fly this kind of airplane. Unless the airplane is being flown into an off-field emergency landing, such systems would almost certainly be a benefit to safety. (And, as Cirrus pilots know: For those emergency situations, there is always the parachute …) It remains to be seen whether Skytron builds an airplane at all — let alone redefines the limits of how little pilot training will be required for a super-automated airplane. Personally, I enjoyed listening to Burt Rutan’s take on the idea; he thinks it could be the next revolution in general aviation. If nothing else, Skytron’s videos are interesting (and short), worth a watch.

There are at least a couple other twins currently in development, such as the Viking VK-42 and the Veloce 400T, both of which have prototypes under construction. According to the latest announcements, the Viking is intended to become a kit for homebuilders, while Veloce is aiming for MOSAIC certification to factory-build its twin. In any case, details are relatively sparse, so I have left them out of this list. Additionally, both of these airplanes use auto-conversion engines; this makes them less appealing to many pilots, myself included. (That having been said, the risks associated with an engine failure are diminished when you have two of them, at least in theory.) And finally, we have the Jabiru J432 from Australia, similar in size to a 172 but powered by two 80-horsepower Jabiru engines, mounted in an unusual configuration!

Speaking of the unusual new engines on some of these airplanes: It is possible that MOSAIC could help some new engine companies join the small number of market leaders by offering innovative (and hopefully less-expensive) powerplant options. Don’t forget how the original Light Sport rules helped Rotax grow far beyond its unreliable two-stroke ultralight past and become a top-notch certified airplane engine manufacturer. Who knows; maybe the big new engines by DeltaHawk or Veloce could become common in a future full of roomy, fast airplanes that are even better than a 185 or SR22. Maybe turboprops will finally become practical for two-seaters and four-seaters. Anything is possible. When it comes to general aviation, thanks to MOSAIC, we are living in exciting times!

Now I just want to know when it will be possible for me to rent an RV-10 S-LSA here in Oregon. I should go knock on the door at Van’s and bug them about it … (again).

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