The Daher TBM 940, Garmin Autothrottle, and the Single Lever That Finally Learned to Move Itself in a Piston-and-Turboprop Cockpit

The Daher TBM 940 became the first single-engine turboprop you could buy from the factory with an integrated autothrottle, introduced in 2019 through a partnership between Daher and Garmin. The system uses electric servos to physically move the power lever, protecting the Pratt & Whitney PT6 turbine from over-torque and over-temperature while guarding against dangerous underspeed and overspeed conditions. It brought a philosophy long reserved for airliners - let the machine handle routine power management so the human can focus on flying - into an aircraft one person can own and operate single-pilot.

What Is the Daher TBM 940?

The TBM 940 comes out of Tarbes, in southern France, the latest descendant of a line of fast single-engine turboprops that began in the early 1990s. It is pressurized, powered by a single Pratt & Whitney PT6 turbine, and cruises at roughly 330 knots true in the low flight level thirties.

That performance lets it carry a pilot and family the length of a continent in an afternoon. By any measure, it’s a lot of airplane for one person to manage - which is exactly what makes its headline feature significant.

Why Was the TBM 940’s Autothrottle a Breakthrough?

In 2019, Daher and Garmin gave the airplane something no aircraft in its class had carried before: a real, factory-integrated autothrottle, fully woven into the Garmin G3000 glass cockpit and the GFC 600 autopilot.

Autothrottle itself is not new technology. Boeing and Airbus have flown it for decades; the autothrottle on a 737 is largely 1980s and 1990s engineering that moves millions of passengers a year. The breakthrough wasn’t inventing the concept - it was making it work in a light airplane, where the engineering is different and harder in ways that aren’t obvious.

How Does an Autothrottle Actually Work?

The name is a little misleading. Most people picture cruise control: set a speed, hold it, done. That’s one function, but not the important one.

An autothrottle is a set of servos - small electric motors - physically connected to the power lever. The flight computer decides how much power the airplane needs, and the servos move the lever to deliver it. You can watch it slide forward and back under your hand as if a ghost were flying the airplane.

Critically, in the Garmin system, you can override it any time by simply grabbing the lever and moving it yourself. It isn’t locked. Your hand always wins.

What Does the Autothrottle Protect You From?

Two things, and they are the two that break engines and hurt people in high-performance singles.

Engine Limits at the Worst Possible Moment

A PT6 is a tough, superb engine, but it has limits: torque limits, temperature limits (inter-turbine temperature, or ITT), and compressor speed limits. On a hot day at a high-altitude airport, shoving the power lever fully forward for takeoff can exceed those limits in about two seconds. An over-temp event can trigger a hot section inspection that costs more than a nice used car - or, at worst, real damage to an expensive turbine.

Historically, a TBM pilot handles this by advancing power slowly and watching the gauges on every takeoff: torque coming up, temperature coming up, find the sweet spot, hold it. It’s a heads-down, hand-on-the-lever task at the busiest, lowest, most dangerous moment of the flight - rotation.

The autothrottle does that task perfectly in a fraction of a second. Push one button, and the lever runs forward to exactly the power the engine can make today, at this temperature and altitude, stopping precisely at the limit. The data points one direction: over-temp and over-torque events on these airplanes are overwhelmingly a human-workload problem, not a mechanical one. Remove the human workload at the critical moment and the problem largely disappears.

Energy and the Danger of Getting Slow

The second protection is more serious: speed, or the lack of it. A pressurized turboprop in the flight levels operates in thin air, where the margin between how fast you’re going and the speed at which the wing stops flying gets narrow. Pilots call the extreme version of this coffin corner, and while a TBM doesn’t fly that high, the principle bites lower than you’d expect.

The Garmin autothrottle is tied into the airplane’s angle-of-attack and airspeed system and includes underspeed and overspeed protection. If the airplane starts getting slow toward a stall, the autothrottle pushes the power up on its own to save you, even if you never touch anything. If you’re diving toward the never-exceed speed, it pulls the power back. It watches the number you’re supposed to be watching, all the time, and never gets distracted.

Attitude vs. Energy: The Complete Picture

Here’s a useful analogy. A good autopilot doesn’t just fly straight and level - Garmin’s electronic stability system will nudge you off a steep bank or a nose-low dive even when the autopilot is off. The autothrottle applies that same philosophy to energy.

Attitude is where the nose is pointed. Energy is how much speed and altitude you have in the bank. A modern cockpit now watches both: the autopilot minds the attitude, the autothrottle minds the energy. Together they close the loop on the two ways a distracted pilot gets hurt.

What’s the Downside? Automation Dependency and Mode Confusion

There is a real caveat, and pretending otherwise would be hype. The concern is automation dependency and skill erosion. If the lever moves itself on every takeoff and manages speed on every approach, do you lose the feel for doing it by hand?

This isn’t a worry invented by grumpy old pilots - it’s the central finding of decades of airline accident investigation. The FAA (Federal Aviation Administration) has warned for years about pilots who supervise automation beautifully but have gone rusty on hand-flown fundamentals. Real airline accidents, with real fatalities, have involved highly automated crews who were surprised by their own systems and lacked the manual habits to fall back on.

There’s a subtler version called mode confusion. When the autothrottle is one of several systems managing your energy - alongside the autopilot’s pitch mode and the flight director - you can lose track of which system is in charge of what. The classic trap is assuming the autothrottle will wake up and add power to save you, when it’s actually in a mode where it won’t. That exact misunderstanding has brought down transport jets. The lesson isn’t that autothrottle is bad; it’s that you must genuinely understand the modes and keep your attention in the loop.

Why the TBM’s Design Learned From Airline Mistakes

To Daher and Garmin’s credit, the light-airplane implementation sidesteps some airline-era traps. In some big jets, the throttles don’t physically move, so crews lose the tactile feedback of watching the levers walk forward and back. In the TBM, the lever moves under your hand - you feel it and you see it.

That physical honesty - the lever telling you the truth about what the system is doing - is exactly the feedback accident reports said was missing. It’s a smarter design because it learned from the mistakes that came before it.

Still, the fundamental responsibility doesn’t change. The autothrottle is a tool that reduces workload so you can spend attention on flying and decision-making. It is not a reason to stop knowing how to set power by hand. The best operators use it to offload the routine, then regularly turn it off and hand-fly to keep the skill sharp. Automation is a lever you pull when you need it, not a hammock you climb into.

Who Built It, and Where Is This Going?

The engineering came from the partnership between Daher, the airframer in France, and Garmin, based in Olathe, Kansas, which supplies the integrated avionics in a large share of new general aviation airplanes.

Crucially, this wasn’t a bolt-on. The autothrottle is woven into the entire G3000 system, talking to the autopilot, angle-of-attack sensors, air data computer, and engine monitoring as one integrated brain. Anyone can put a servo on a throttle; making it cooperate safely with everything else in the panel - and fail gracefully when a sensor disagrees - is the hard part, and the part that required real certification work with the FAA and European authorities.

The direction of travel is unmistakable. The same core Garmin technology has spread through the Daher line and toward other high-performance singles and light jets. Autothrottle is migrating down from the airlines, into business jets and turboprops, and is now knocking on the door of the high-end piston world. The barrier was never physics - a piston engine has power and speed limits just like a turbine - it was cost and certification. Every year the electronics get cheaper and the certification path gets more worn-in. Give it time, and the moving throttle stops being an exotic feature on a French turboprop and becomes something you simply expect on a new high-performance airplane, the way we came to expect a glass panel and a two-axis autopilot.

Key Takeaways

The Daher TBM 940 was the first single-engine turboprop with a factory-integrated autothrottle, introduced in 2019 with Garmin.
The system physically moves the power lever via servos, protecting the PT6 turbine from over-torque and over-temp at takeoff - events that are largely a human-workload problem.
Tied to the airplane’s angle-of-attack and airspeed data, it provides underspeed and overspeed protection, adding or reducing power automatically to guard the airplane’s energy.
The real risks are automation dependency and mode confusion; the moving-lever design preserves tactile feedback that some airline systems lack, but pilots must still hand-fly to stay sharp.
Autothrottle technology is migrating down from airliners toward business jets, turboprops, and eventually high-performance pistons - limited by cost and certification, not physics.