What is a flight director?

noahfong

Pre-takeoff checklist
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Noah
From reading another post, it was clear to me that many do not know what a flight director is which leads to confusion as to its benefit. I thought I'd give a stab at helping folks understand what it is and what it does.

flight_director.jpg

In the picture on the left, the airplane symbol is changed to a triangle (in this case - it's often a chevron). The symbol above it is the "cue" or the flight director symbol. (This is a single cue system). If, and that's a BIG "IF", you "program" (I like to say, "sync'd") your flight director to what you want in the flight, it will "direct" you to follow it by "tucking" the airplane symbol beneath the cue (as you see in the picture on the right).

Let's say you sync'd the FD for a 500fpm climb or a 10deg pitch up climb and/or a certain heading....you would see something like the picture on the right if you are following it.

It gets better than that...it will level you out when you get to your "set" target altitude. It will "pitch" you to hold a certain airspeed. It can hold a heading for you to join a localizer or course and join it for you IF you armed it appropriately. All you have to do (practically) is to keep the FD and the airplane symbol locked together - much easier to do than scanning a six-pack.

It is a great device but you have to know how to push buttons and twist knobs AND actually do it. Otherwise the FD will not be sync'd to what you want. (This is why you see some people fly with the FD way over in some corner). This can make you pretty busy at times and if you make a mistake, you'd better know how to correct it quickly. (Especially if you're on autopilot about to punch through an approach course - in which case, also be ready to hand-fly).

If you get lazy, and your plane is auto-pilot-equipped (and it works), you can activate the autopilot and it will follow the flight director for you.

There are "double cue" systems. I've only flown them in sims. If memory serves, the cue consists of a vertical line (for course) and a horizontal line (for pitch). In addition to a normal airplane symbol, there is a small square symbol....and you follow the cues by getting the square centered on the "crosshairs". Someone correct me if I'm wrong. I've only seen this in actual operation once when jumpseating on an Airbus...I remember thinking, "wow! This guy really holds a perfect approach!" - then I saw his screen - square perfectly centered in the crosshairs.

Hope this helps.
 
Another way to look at a flight director...

It merely is a thing that tells the pilot what the autopilot would do if engaged, in terms of lateral and vertical guidance.

Flying one is kinda like extra work, you have to fly AND program the autopilot, or flight management system.

Most procedures require the flight director to be displayed before engaging the autopilot, but not all... but it’s ALWAYS a good idea.

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