A lot of general aviation pilots don’t know what a flight director is, let alone how to use it. Most of us received our instrument training on either steam gauges without a flight director, or a glass panel with not autopilot (hence no flight director). Or, your CFII didn’t know how to utilize the flight director, so you as the pilot were never taught about it.
Let’s start off with a definition. What is the flight director and what is its purpose? A quick search of Wikipedia gives us a solid technical definition of the term: “A flight instrument that is overlaid on the attitude indicator that shows the pilot of an aircraft the attitude required to execute the desired flight path.”
Still confused? Think of it this way. The flight director tells either the autopilot (if the autopilot is on) or the pilot (if the pilot is hand flying) how to position the attitude (both pitch and bank) of the airplane to achieve any number or desired outcomes. Those could be:
- A climb or descent pitch attitude to maintain a certain vertical speed
- The pitch attitude needed to maintain an altitude at a certain power setting
- The bank angle needed to achieve a half standard rate turn to a heading or course
- Bank angles that are needed for course or heading corrections
- The pitch attitude needed to keep a glide path or glide slope centered on an approach
The theory is, using a flight director simplifies the instrument scan. Without a flight director, an instrument pilot has to scan 7 different instruments on a glass panel airplane (pitch attitude, bank attitude, yaw, airspeed, altitude, heading/course, and rate of turn). A properly utilized flight director allows the pilot to focus the scan on the attitude indicator while only needing to reference the other instruments. That is, assuming the pilot has pushed the correct buttons on the autopilot control head to tell the flight director what to do. We’ll come back to this in just a second.
When the autopilot is on, the flight director will automatically be on. An autopilot has to have a flight director to reference since it is directing the autopilot where to go. If you think about it, when you are changing modes on the autopilot, you are telling the flight director what you want to the airplane to do, then it “directs” the autopilot where to go.
When a pilot is hand flying and utilizing the flight director, the same buttons on the autopilot need to be pushed to tell the flight director what to do. Then, the flight direct “directs” the pilot where to fly the airplane. So, if the pilot wants to fly a heading, push the heading button on the autopilot control head (making sure the autopilot is off), then set the heading bug on the desired heading, then the flight director will show the pilot what bank angle to fly, then it will show the pilot when to roll out to intercept the desired heading.
The same is true for flying a course (the flight director will even “direct” the pilot to fly a wind correction angle to maintain the course on most glass panel airplanes), maintaining an altitude, climbing and descending, etc.
One mistake that I see pilots make a lot is when climbing or descending, the pilot forgets to push the VS button on the autopilot controller when hand flying with the flight director. The pilot will set the altitude selector, then start a climb or descent without pushing VS. Since the pilot didn’t tell the flight director that a climb or descent was needed, the flight director is still “directing” the pilot to maintain the previous altitude. So, it’s either showing a pitch up or pitch down attitude, depending on where the previous altitude was selected. Remember, if a climb or descent is initiated while hand flying with the flight director, push VS on the autopilot control head and set the VS that is desired, just like the autopilot were on.
How can you tell if the flight director or autopilot is flying the airplane at a quick glance? Typically, in most Garmin and other glass panel equipped airplanes, the flight director is magenta and positioned on the attitude indicator. If the autopilot is on, the flight director will be filled in. If the autopilot is off, the flight director will be hollow. See the pictures below for reference. The autopilot is on in the top picture and the autopilot is off in the bottom picture.
Hopefully after reading this, pilots will have a better understanding of the flight director and how it can be used as a great tool in flying.