More Garmin Autothrottle: Safety Backstop for Big King Airs

As Garmin’s Emergency Autoland and Autothrottle become standard in a variety of new turbine aircraft, Garmin continues to advance the tech for field retrofits. The latest includes select Beech King Air 300- and 350-series turboprop twins. In the latest FAA STC, the Autothrottle is certified for King Air 300 aircraft equipped with four-blade propellers and Pratt & Whitney PT6-60A engines. Both Autoland and Autothrottle are certified for King Air 350 aircraft also equipped with four-blade propellers and the PT6-60A engines. For all applications, a Garmin G1000 NXi integrated flight deck is required. And as it is with Garmin’s retrofit Autoland and Autothrottle for King Air 200 models, installations will be accomplished through select Garmin Authorized dealers. Worth mentioning is there have been over 1000 King Airs retrofitted with Garmin’s G1000 system—a big number in the world of major flight deck transformations. It also proves that owners are willing to spend big to bring these workhorses to a modern level.

And the Autothrottle system indeed brings the King Air to a higher level when it comes to single-pilot ops and backstop during an engine failure. When I flew with the system in Garmin’s King Air 200, I was surprised at Autothrottle’s precision and smoothness. Part of it falls on Autothrottle’s servo actuator, which is based on Garmin’s GSA 87 autopilot servo—an electromechanical microprocessor-controlled unit with a brushless motor that’s notably a good performer. The system uses a new GMC 711 mode controller with speed selector switches, and there’s an automatic FMS mode for tracking predefined speed or power targets from the G1000 NXi’s flight management system.

Real-World Utility

The Autothrottle takeoff is as simple as arming it and advancing the power levers beyond the 1,000 foot-pound settings. The Autothrottle engages and annunciates (ATT/O) on the upper left of the G1000 NXi MFD near the power gauges, verifying that the computer has command of the power. If an engine fails, the autopilot-based OEI ESP (standing by in the background and detecting that the autopilot’s rudder boost has activated) will adjust the PFD’s roll limit indicators from 45 degrees inward to 10 degrees toward the failed engine and 40 degrees on the good engine. The pitch limits shrink from 20 to 10 degrees nose up and from 15 to 5 degrees nose down. OEI ESP is disabled with a push-button panel switch, where the system returns to the autopilot’s normal ESP mode. There’s also automatic low-airspeed protection when below Vmca plus 15 knots indicated.

The idea is to minimize excessive attitudes when dealing with the power loss. Like other ESP applications, you feel slight pressure on the flight controls to hopefully guide you back to recommended control inputs. During an engine failure after V1 (90 knots is Garmin’s conservative programmed number for the King Air 200) with the Autothrottle engaged, both Autothrottle servos park. Think in terms of a heavy-duty friction lock, but light enough to overpower. There’s a “check power” aural alert for the pilot to verify a failed engine. From a mechanical function, if an engine fails in the climb, cruise or approach, the system parks the failed engine’s power lever (during the failure the lever would likely advance to the max torque position as it tries to add power) and it’s up to the pilot to disconnect the autopilot and the Autothrottle and secure the failed engine.

Autoland, Too

Some may think the big news is FAA STC for Garmin’s Emergency Autoland, but I think the Autothrottle is the bigger news for pilots regularly operating these King Airs, especially with its deep integration with the G1000 NXi’s FMS. Still, Garmin sees value in Autoland for these big turboprops, and it has been a major selling point for Autoland-equipped new turbine models—from Piper M600/700 singles to Daher TBMs to Cirrus SF50 Vision Jets, to name a few. And what else can be written about Autoland that already hasn’t been written? In the event of an emergency, pilots or passengers can activate Autoland by pressing the guarded switch that’s located in the back of the King Air’s center pedestal. Autoland will activate automatically if the system determines it’s necessary, as in pilot incapacitation.

Still, the Autothrottle is integral to an Autoland activation—climbing, descend and maintaining altitude as needed. If temperatures are right for building ice on the airframe, the Autoland activates anti-ice and deice systems for the engines and control surfaces. If the King Air needs additional time to descend or slow down during the approach, the Autoland initiates a standard holding procedure, and Autoland configures the landing gear and flaps for a runway landing. Once on the runway, automatic braking is applied while tracking the runway centerline to bring the aircraft to a complete stop. Engine shutdown is automated, and instructions are given to the occupants on how to operate the cabin door and exit the aircraft. 

Garmin’s latest G1000 NXi for the King Air has SafeTaxi, with a 3D exocentric view of the airport environment for ground ops. Because it uses Garmin SVT (Synthetic Vision Technology), it also displays 3D building footprints including hangars, terminals and towers, taxiways, aprons, signs and other markings. The idea is to help reduce runway incursions with automated guidance while taxiing at airports that are in the SafeTaxi database. Add Garmin’s GWX 8000 set-it-and-forget-it StormOptix ship’s weather radar, and it really is an ultramodern flight deck upgrade and a major shot in the arm for aging King Airs.