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   autothrottle by developing a servo that could manipulate the throttle to control speed.
“From an autopilot perspective, we spent a lot of time on the basics of the 200 feet down to the runway surface: the flare, the low-speed ground effect, the landing. Then we tackled the last piece, which was the ground control, the aircraft’s braking and steering,” said Ben Patel, the team leader for Garmin’s flight controls group.
To test and perfect the landing sequence, engineers modified the aircraft’s airport database by devis- ing a series of virtual runways at 5,000 feet above the Kansas eastern plains. Then they “landed” the air- craft hundreds of times on those simulated runways.
“It’s similar to how a ski jumper will practice landing in a pool be- fore actually landing on the actual ski slope. We landed at these vir- tual airports so we could practice the flare maneuvers and make sure the algorithms worked in different crosswind conditions,” Patel added.
At first Garmin tried using GPS alone as its guidance source for the short-final to landing sequence. The results were mixed depending on how good the GPS signal was that day. Although Garmin believed the algorithms worked reliably to ac- count for the GPS error, engineers knew it could be further perfected with the addition of radar altimeter, so that instrument was integrated. In February 2016, Garmin success- fully completed its first real runway landing at KIXD. By the spring of 2019, Garmin had completed 800 flights and many, many more land- ings in the Piper M600SLS.
How Autoland
Chooses Its Destination
On the software side, Garmin’s engineers worked on figuring out how to take all the discreet decisions a pilot makes and create a system of prioritization for different combina- tions of circumstances and condi- tions. For example, the algorithm considers and then assigns a weight to a whole host of criteria, such as
 December 2019 / TWIN & TURBINE • 13
Always on Watch:
Autoland Keeps Tabs on Itself
Garmin not only imagined all that the Autoland can do, it was mindful of what it can and can’t do if part of the system is inoperable.
When the pilot powers up G3000 for a flight, the system runs through a normal avionics pre-flight test in which the Autoland components are checked. If an anomaly or failure is detected, a CAS message is posted to inform the pilot. If Autoland or one of the components that it uses is detected to be nonfunctional, the pilot would then have the choice of whether to dispatch on that flight with all or part of Autoland inoperative. If Autoland itself is flagged during the pre-flight test, it’s important to note that the autopilot will continue to function even if Autoland is inoperative.
Where Garmin could partition the functionality and isolate components, such as a brake servo or radar altimeter, they have done so. Thus, if a brake servo fails the self-test, it won’t completely disable the entire Autoland system. However, there are a few essential components that Autoland must have, such as the autothrottle and the pitch servo.
In flight, Autoland is constantly monitoring the health of all its key components required for its function. In the improbable event that the radar altimeter or a brake servo were to fail inflight while Autoland is activated, Autoland will continue with the landing with the capabilities it still has. In this example, it will use GPS for altitude sensing or land without activating brakes.
“We’ve made the system so flexible for OEMs that we haven’t even begun to use all ways it might be configured. While it is fully autonomous, but it could potentially be configured to have a passenger intervene or perform a task if necessary. For example, the system could provide step-by-step instructions to the passenger, even show a picture that says, ‘move this knob or lever and make it look like this’,” said Bailey Scheel, Garmin’s senior programs manager and systems engineer. “That might be a feature made available in a smaller aircraft installation that has less functionality or automation, but still get the benefit out of the technology.”
An example of Autoland’s vast configurability is seen in the Piper M600SLS Halo that incorporates Autoland. If a passenger’s hands or feet touch the controls while Autoland is active and the system senses the controls being moved and posts a message stating, “Keep your hands and feet away from the controls.”

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