GFC 700 AFCS Supplement GFC 700 AFCS Supplement Autopilot Basics Flight Director vs. Autopilot Controls Activating the System Modes Mode Awareness What the GFC 700 Does Not Control Other Training Resources Automation Philosophy Limitations Modes Quick Reference Tables Lateral Modes Vertical Modes Lateral Modes Roll Hold Heading Select (HDG) Navigation (NAV) Approach (APR) Backcourse Vertical Modes Pitch Hold Altitude Hold (ALT) Glidepath (GP) Glideslope (GS) Go Around (GA) Selected Altitude Capture (ALTS) Autopilot Procedures Preflight Takeoff / Departure En Route Arrival/Approach Approaches Without Vertical Guidance Approaches With Vertical Guidance Revised: 02/08/2021 Missed Approach Autopilot Malfunctions/Emergencies Annunciations Cautions (Yellow) Warnings (Red) Emergency Procedures Manual Electric Trim Control Wheel Steering C172 w/ GFC700 Autopilot Checklist Piper Archer w/ GFC700 Autopilot Checklist Supplement Profile Addenda Autopilot Basics Flight Director vs. Autopilot ATP’s newer Cessna 172s and Piper Archers come factory-equipped with the GFC 700 Automatic Flight Control System (AFCS). The GFC 700 AFCS, like most autoflight systems, includes both a flight director (FD) and an autopilot (AP). The FD calculates the pitch and bank angles needed to fly the desired course, heading, altitude, speed, etc., that the pilot has programmed. It then displays these angles on the primary flight display (PFD) using magenta command bars. The pilot can follow the desired flight path by manipulating the control wheel to align the yellow aircraft symbol with the command bars. Alternately, the pilot can activate the AP, which uses servos to adjust the elevators, ailerons, and elevator trim as necessary to follow the command bars. Controls The AFCS is activated and programmed using buttons on the left bezel of the PFD and the multifunction display (MFD). The two sets of buttons are identical, but the set on the MFD is easier to reach (and easier for the instructor in the right seat to see, to confirm proper operation). There are 4 buttons on the left side of the pilot’s control wheel (and in the Piper Archer, also on the right side of the copilot’s control wheel) that serve to disengage the autopilot and operate the electric trim. These are positioned such that the pilot can press them with their thumb while using the control wheel. On Cessna 172s, one additional button, the Go Around Switch, is located near the throttle so the pilot can advance the throttle and push the button in one motion during a go-around. On Piper Archers, the equivalent Takeoff/Go-Around Switch is located on the throttle lever. Operating these controls brings the pilot’s attention inside the aircraft, particularly for pilots who are not yet completely familiar with their operation. This could distract the pilot from their Revised: 02/08/2021 obligation to see and avoid other aircraft. Pilots using autoflight systems must be conscious of how much time they are spending heads-down. Alternate between scanning for traffic and operating the autopilot. If you cannot devote enough heads-up time to collision avoidance while simultaneously programming the autopilot, stop using the autopilot. Fly by hand, and become ​ ​ more familiar with the GFC 700 before using it on future flights. Activating the System Pressing the FD button will activate the FD but not the AP. Then, to activate the AP, press the AP button. If the FD is not already active, pressing AP will activate both. Modes To use an AFCS, the pilot must select one or more FD modes that tell the system what to track: ​ ​ a heading, a navigational signal, an airspeed, a vertical speed, etc. For the GFC 700, these modes are divided into two groups: vertical modes and lateral modes. The pitch angle shown by the command bars is determined by the vertical mode, and the roll angle is determined by the lateral mode. In some circumstances, the pilot may want the FD to use one mode until some condition is met, then switch to another mode. For example, the pilot might want to fly a particular heading to intercept a VOR radial, or to climb at a particular airspeed before leveling off at a given cruising altitude. In this case, the mode currently being used is called the active mode, and the one to ​ ​ which the AFCS will switch is the armed mode. ​ ​ Mode Awareness One of the most common causes of autoflight errors is a lack of mode awareness. That is, the pilot loses track of which mode the AFCS is in, and therefore fails to anticipate how the AFCS will behave. The key to maintaining mode awareness is to keep the AFCS Status Box in your scan. This box is at the top of the PFD, just below the Navigation Status Box. It is divided into three segments: ● Left: lateral mode annunciations ● Right: vertical mode annunciations ● Center: autopilot status annunciations Active modes are displayed in green and are towards the center of the PFD. Armed modes are displayed in white and are towards the edges of the PFD. When the AFCS transitions from an armed to an active mode, the white armed annunciation moves to the green active mode field and flashes for ten seconds. If the mode annunciation flashes yellow, the AFCS has lost the sensor or navigation data needed to compute commands in that mode. The aircraft will roll wings level or hold the current pitch angle (depending on the affected axis). The annunciation will flash for 10 seconds, then revert to the Pitch Hold or Roll Hold mode. Revised: 02/08/2021 While the AP is engaged, a green “AP” annunciation appears in the center of the AFCS Status Box. If the AP is manually disengaged, this annunciation will flash yellow for 5 seconds (along with a two-second disconnect tone) and then disappear. If the AP is automatically disengaged, it will flash red (along with the aural disconnect alert) until the pilot acknowledges the alert. Scanning the AFCS Status Box is critical for mode awareness, but scanning for traffic is critical for collision avoidance. Alternate your scan: traffic, AFCS status, flight instrument readings, back to traffic, etc. If monitoring the automation is requiring so much attention that your traffic scan deteriorates, shut off the automation and fly by hand. What the GFC 700 Does Not Control The GFC 700 AFCS has no control over the throttle setting of the aircraft. The pilot must adjust the power as necessary to maintain the desired flight profile. In descents, failure to sufficiently reduce power could lead to an overspeed condition. In climbs, failure to sufficiently increase power could result in minimal climb rates or dangerously low airspeed. The GFC 700 also has no control over the aircraft’s rudder. It is a two-axis autopilot, meaning that it controls pitch and roll but not yaw. The pilot must keep their feet on the rudder pedals and make appropriate inputs to keep the aircraft in coordinated flight. Other Training Resources The flight environment is a distracting and expensive place to learn how to operate an autoflight system. Fortunately, there are a wealth of resources available to learn about the GFC 700 on the ground: ● “GFC 700 Training” video on the Garmin YouTube channel ​ ● King Schools “Flying the Garmin G1000” course ● Manuals: G1000 Pilot’s Guides, Cockpit Reference Guides, aircraft POH/AFM ● Garmin G1000 Trainer software Automation Philosophy When using an autoflight system, it is critical to remember that you, the pilot, are still flying the ​ ​ airplane. You are pressing buttons and turning knobs, instead of moving a control wheel, but you must still… ● Evaluate the current flight conditions. ● Choose a course of action that will keep the flight safe and legal. ● Make appropriate control inputs to carry out that course of action. ● Monitor the aircraft’s response to your control inputs. ● Adjust your control inputs if the aircraft is not behaving as desired. An autopilot is a useful tool for relieving some of the physical workload of flying the airplane, but it cannot take on the mental workload required to exercise good aeronautical decision-making ​ ​ (ADM). Autoflight systems will behave exactly the way they’re programmed by Garmin’s engineers and the pilot, even if that behavior is illogical or unsafe in the current situation. As a result, like any computer, the GFC 700 can only ever be as good as the pilot who is using it. Revised: 02/08/2021 The autopilot also has no ability to scan for and avoid traffic. Whenever weather conditions allow, all pilots (whether VFR or IFR) are required to maintain vigilance so as to see and avoid other aircraft (14 CFR 91.113). Using an autopilot does not relieve you of this responsibility! The idea of “staying ahead of the airplane” applies very much to the use of autoflight systems as well. When using the autopilot, you should know exactly where you expect the aircraft to be and what you expect it to do well before it actually happens. If you don’t, you won’t be able to catch any errors, malfunctions, or other unexpected behavior. While flying on autopilot, ask yourself occasionally: ● If it disconnected right now, could I immediately jump in and continue with the flight? ● If it started deviating from the flight path I want it to take, would I know immediately? If you can’t answer “yes” to both questions, you have allowed the autopilot to get ahead of you. It’s taking you places before you have a chance to apply your ADM skills, and it has no ADM skills of its own--this is not a good combination. Limitations In Cessna 172 aircraft, the autopilot feature of the GFC 700 AFCS may not be used: ● During takeoffs and landings.