An Introduction to the GFC 700
by Brandon Ray, CFAI+, CSIP, Master CFI, ATP, Gold Seal CFI, CFII, MEI, AGI
Ever wish your airplane could fly itself? With the Garmin GFC 700, that vision is getting closer to reality. In the past, some GA aircraft have been equipped with rate-based autopilots, like the S-TEC 55X or the Bendix-King KAP 140. Some of these autopilots would allow the aircraft to fly standard-rate turns, hold altitudes, command wings-level, and even couple to instrument approaches, depending on the particular model. With the Garmin Flight Control system, we now have access to incredible attitude-based digital precision. This article is designed to help you with the basics of using the GFC 700 for a basic VFR flight scenario. There are many more features and techniques that we may discuss in later articles.
NOTE: Although there are many variations of the GFC 700 Autopilot, this article is based on the configuration found in the Cessna Nav III.
Components and Definitions
AFCS – Autopilot Flight Control System (specifically, the Garmin Flight Control System – GFC 700)
Flight Director (FD) – Provides the following:
- Command Bars showing pitch/roll guidance
- Pitch/roll mode selection and processing
- Autopilot communication
Autopilot (AP) – Autopilot operation occurs within the pitch, roll and pitch trim servo and provides servo monitoring and automatic flight control in response to flight director steering commands, AHRS attitude and rate information, and airspeed.
Manual Electric Trim (MET) – The pitch trim adapter provides manual electric trim capability when the autopilot is not engaged.
Using the Flight Director
To begin, let me state that
The flight director is NOT the autopilot.
The flight director simply serves to provide instructions to the autopilot, or to the pilot (depending on the mode selection). Many professional pilots use the flight director for nearly all of their flying, so they can continue receiving guidance even when hand-flying the aircraft.
The yellow aircraft symbol represents the attitude of the aircraft. The magenta command bars represent the guidance from the flight director. While flying with the flight director, you simply match the top of the aircraft symbol to the bottom of the command bars. The modes you select will control what the command bars display. You can select a specific pitch, airspeed, heading, course, or altitude if desired. Without a flight director, you would focus on scanning the instrument: looking at the attitude indicator, altimeter, VSI, airspeed, and heading. Now, it is as if the flight director does the scanning for you.
The FD key allows you to turn the flight director on or off. When the flight director is initially turned on, it defaults to the Roll (ROL) & Pitch (PIT) modes. This means that it will direct you to continue holding the same bank and pitch as when you first pressed the key. Then you will continue selecting the desired modes.
NOTE: The flight director may be used without the autopilot, but the autopilot may not be used without the flight director. If desired, the autopilot can be selected first (AP) and the flight director will appear automatically in the default modes. The following example may be used with just the flight director if you want to hand-fly the commands… OR… Let the autopilot do the work and you can watch the results in action.
IMPORTANT: Who is flying the airplane? You or the autopilot? The indication is subtle, but the answer is found in the small “AP” indication at the top center of the PFD in the autopilot status bar.
- Green AP = Autopilot is following the flight director commands
- If the center of the status bar is blank or shows a yellow or red AP, then the autopilot is not flying the plane, so you have the controls (or at least you should!).
Typical VFR Flight Example:
- Autopilot preflight test completed
- Select desired altitude (ALT knob)
- Sync heading bug when aligned with runway (press HDG knob)
- Know the minimum altitude for autopilot use (varies depending on the airplane model 400’-800’ AGL is common.)
My typical after-takeoff flow goes something like this:
- FD or AP on (defaults to pitch and roll modes)
- Sync heading bug or select desired heading
- HDG – FD follows the heading bug
- NAV – This will arm the NAV mode to capture the course assuming I’ve chosen an acceptable intercept angle with my heading bug for my desired course. NOTE: This does not automatically pick an intercept angle for the course – You must set the initial intercept angle and then it will capture the course when the CDI needle centers.
- FLC (or VS) – Holds indicated airspeed or vertical speed, respectively.
- NOSE UP or NOSE DN – To select the desired airspeed or vertical speed.
The Resulting Climb Modes:
- GPS HDG AP FLC xxKT ALTS
- Once you intercept the course and the course captures, you will see the following:
- GPS AP FLC xxxKT ALTS
- Translation: Tracks your GPS course, while maintaining the indicated airspeed until reaching the selected altitude where it will level off.
The Resulting Cruise Modes:
- GPS AP ALT XXXX FT
- Translation: Maintains GPS course and altitude at XXXX. You will be in this mode for most of the flight.
- Select Desired Altitude (ALT Knob) – Traffic pattern altitude perhaps?
- Select mode of descent (VS, PIT, VNV, etc.) – VS is typical for descents.
- Adjust the rate of descent – It defaults to the current rate at the moment you select VS, which is probably 0 fpm if you are in level flight. Just press the NOSE DN key 5 times to get 500 fpm.
- The autopilot status bar should now show the following:
- GPS AP VS 500fpm ALTS
- Translation: You will stay on course as you descend at 500 fpm until reaching your selected altitude at which time the FD will capture the selected altitude to cue the level-off.
- Upon reaching the selected altitude, the FD will level off and you will see the following indication:
- GPS AP ALT xxxxFT
- You can now disconnect the autopilot and turn off the flight director as you hand fly your arrival into the traffic pattern.
BEST PRACTICES TIP: Make it a habit to turn off the flight director anytime you disconnect the autopilot unless you intend to follow it. It’s a bad habit to keep the flight director on if you don’t intend to follow it, as it can prove to be a distraction. It can also create some surprises later if you decide to turn the autopilot back on, not expecting it to try to capture the last selected modes. After pressing the red autopilot disconnect button on your yoke, simply press the “FD” key to turn off the flight director, and the magenta V-bars should disappear.
As always, feel free to leave a comment or send us a Facebook message if you have any questions. We will look forward to writing about some of the more advanced autopilot features in the near future!
References: Garmin G1000 Pilot’s Guide for Cessna Nav III (190-00498-06 Rev. B)
How it Started
One of my best friends in high school, (Doug Gray) was a private pilot. He offered to take me up for a flight in a 1967 Cessna 150, N6228S. We took off from Calhoun, Georgia, and he took me on a scenic tour of the area, I was hooked. I later found out that my English teacher, (Jan Haluska) was also a flight instructor and the school was offering a ground school course the next year, which he taught, along with flight training with the goal of becoming a private pilot. I managed to talk my dad into funding the training, at the time the total cost was right around $500. Cessna 150 rental rates where $12 an hour, and the 172 we used for cross country was $15 an hour including fuel.
It started August of 1977. The fall semester rolls around, and I am enrolled in ground school, and if memory serves me, we met twice a week. First came the paperwork for my student pilot certificate, which at the time was included with the 3rd class medical. I loved ground school, especially learning navigation, plotting courses on the sectional, again this was before iPads and GPS, so we did a lot of dead reckoning and VOR navigation for cross countries. At the end of the course, I made an 83% on the Private Pilot written exam, remember this was before we had the question-and-answer books that on future test I would consume before taking a written.
The fun really began on August 22, 1977, it was my first flight. To my surprise we used the same Cessna 150, N6228S that my friend Doug Gray had taken me for a ride in. The Cessna 150 had a standard VFR instrument panel, with one NAV/COM, and one VOR CDI. No intercom, so no headset, at the time I didn’t know what I was missing. I didn’t get my first headset until I started my instrument training in 2003. I was a big guy, I was 6’ 4” and weighed 245 lbs. but I do not remember being uncomfortable in the 150 even with the instructor in the right seat.
First flight lasted .8 hours, and we accomplished orentation, shallow turns, stability, and effects of flight controls. Over the next few months we added steep 720’s, slow flight, stalls, turns around a point, S-turns, emergencies, landings, (short field, soft field and normal).
At this point I want to talk about a training experience that still stands out. We were close to solo and were practicing takeoffs and landings. Turning base to final Jan got very upset at the way I was cross controlling the aircraft. Cross control is when you are in, say a left turn, and use opposite rudder to line the nose up with the runway. So, he had me depart the pattern and head east to the practice area, and climbing up to 5500 feet MSL, he had me slow down to just above stalling speed, start a left shallow turn and add right rudder. As the airplane stalled I had the strangest sensation, no roller coaster has ever come close, instead of blue sky in the windscreen I was looking at brown ground, and as far as I could tell we were upside down, through the terror of the moment Jan talked me out of the spin, controls neutral, oposite rudder, pull slowly out of the dive. As we leveled off he asked me what altitude we were at, as I remember it was around 2,800 feet MSL. Then he asked me what would happen if I experenced this on base to final in the traffic pattern. The answer was obvious, I would be a pile of wreckage off the end of the runway with a very short-lived aviation career. Needless to say this cured my cross-control tendencies.
Another training event the sticks out in my mind was the first time we did takeoffs and landings at the High School runway. The runway was 1,500 feet long, not sure of the width, but it seems like we had about 5 feet on each side of the wheels when on the center line of the runway. Landing from the south you also had to go between a cutout in the trees to be able to stop in time on the runway. After getting confortable landing here every runway since seemed huge. I remember landing at Chattanooga (KCHA) on a night cross country and commenting to Jan, that I felt like I could of landed sideways on the runway, it felt that large.
Very soon after this I started wearing old shirts to all my flight lessons, the reason for this occurred on February 8, 1978. The lesson that day was stalls, takeoffs and Landing. As we were taxing back in Jan told me it was time for my first solo. I was very excited, and after some last minute advice from Jan, including watch for floating on landing the plane will be light with him not in the right seat, complete 3 takeoffs and landings to a full stop. It was a blast, and at the end of my shirt was shorter in the back because Jan cut the tail out of it signed and dated my solo [an aviation tradition]. Total flight time accumulated on the day of my solo was 18.1 hours. I was now officially a pilot with solo priveleges.
In my next article I start cross country training, when Jan decided that it would be best accomplished this in the 172. Checking out in N5970R was like moving into a 747, this started a love affair with one of my faviriote planes to date. Since this time I have flown over 900 hours in many different models of the 172 and feel like I am stepping into an old friend every time.
More about Randy here: https://www.flyhpa.com/team/randy-delong/
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