The Gulfstream G150 is the fastest and longest-range midsize-cabin business jet, and now it is the first in the category to offer the safety and improved efficiency of a full-time autothrottle system (ATS). Gulfstream also recently earned full certification for the infrared enhanced vision system (EVS) with the same resolution and definition as the system offered on its large-cabin airplanes.
Gulfstream was the first business jet to offer an ATS when it introduced the G-III more than 30 years ago. Since then an ATS has been the norm in the large-cabin Gulfstreams. An ATS has also been available in the super midsize cabin G200. And now the AutoPower system in the G150 makes ATS available across the entire Gulfstream line, a strategy that is in keeping with offering the Plane-View cockpit and EVS in each model.
The most important reason Gulfstream offers an ATS is increased safety. The AutoPower system will hold the target approach speed within a knot or two even in gusty and bumpy conditions, and arriving over the runway at the VREF target is the best protection against an overrun, which is one of the most common types of accidents in business jet flying.
While it holds approach speed perfectly, the AutoPower also constantly monitors angle of attack and will simply not allow the G150 to get close to a stall. This is important, obviously, during landing approach but is also a safety edge if the crew were ever to become distracted and allow the airspeed to decay in any phase of flight. And the crew workload reduction AutoPower adds safety potential, a fact recognized in major airlines and large-cabin business jets for decades.
There are several ways an ATS can be designed and integrated into the autopilot system, and I think the AutoPower in the G150 is one of the most intuitive and pilot-friendly. There really isn't much of anything to learn to use the system, and no button-pushing or other actions are required from takeoff to touchdown. The human pilot can take command of the throttles at any time by simply moving the levers, which offer only slight resistance through clutches that engage the ATS.
The visible parts of the AutoPower system are mode status displays located just outboard of each pilot's PFD, and engagement buttons on the throttle knobs. The guts of the system are Safe Flight's very sophisticated servo motors (inside the throttle quadrant) that actually position the levers, and a computer that is mounted inside the pedestal. AutoPower is available for all existing G150s, as well as on new airplanes, so the compactness of the system, and its small number of components, will make retrofitting a very straightforward and brief trip to a Gulfstream service center.
To see AutoPower in action, Gulfstream experimental test pilot Scott Martin, who headed up the development and certification of the system, and I taxied out just after sunset at Gulfstream's home in Savannah, Georgia. We had spent time discussing how AutoPower works and the various steps in the development program, but nothing like what I would call "training" was necessary to feel comfortable with the system.
Pilots can choose to use the engagement buttons on the throttle knobs to tell AutoPower to set takeoff thrust as they would in the larger models, but a more natural way is to simply move the levers forward themselves. At about 75 percent power, AutoPower takes over and sets takeoff N1 engine speed and shows you that takeoff power is selected on the mode annunciator. That's all there is to it. The system maintains takeoff thrust until transitioning to recommended climb power, which it adjusts automatically as the altitude and air temperatures change on climb.
A more real-world scenario is that you will have a fairly low initial assigned altitude that you will set into the PlaneView automatic flight control system using the normal altitude select knob. When the autopilot — or flight director if you are hand-flying — captures the assigned altitude, AutoPower transitions into speed mode and will move the throttles to maintain whatever airspeed you have selected automatically with no additional pilot inputs.