Flight Director.

[ken999]

Please Could Anybody Tell Me The Purpose Of The Flight Director.Thankyou.

[lnuss]

The flight director is designed to tell you where to fly. Basically, it has a second set of wings on the Artificial Horizon instrument, and you fly so that the aircraft symbol matches the movement of the FD's wings. Obviously you must have used something (FMC, etc.) to tell it what you wanted in the first place.

[ken999]

Thankyou For The Info.

[metz]

>Please Could Anybody Tell Me The Purpose Of The Flight
>Director.Thankyou.

I'll try and give you a little more (maybe too much) detail on what a flight director does and how it works in real aircraft.

First, a flight director is part of an automatic flight control system. In little airplanes (like the mooney, baron, caravan), it's connected to an autopilot. In bigger airplanes, things like autothrottles, route planning software, and other capabilities are added and the whole thing is called a flight management system.

What they all have in common is a computer that knows:

What the plane is doing at the moment (attitude, heading, maybe also altitude, course, track error and other things) based on sensors, and;

What the pilot wants the plane to do, based on the heading bug, the altitude preselect, the FMC, or some other system.

This computer provides guidance for bank, yaw, and pitch servos that will move the flight control surfaces (it can also provide guidance to the autothrottles).

So, with the autoflight system engaged, the airplane does what you wanted it to do (assuming all is working correctly and you didn't tell it to do something stupid).

What a flight director does is show you on your attitude indicator what the autoflight computer thinks your airplane should be doing attitude-wise to comply with the instructions it's gotten from the FMC or your autopilot settings. With the autopilot engaged and functioning correctly, if you turn the flight director on, your little wedge that represents the airplane should be snuggled up next to the flight director bars. Note that you don't HAVE to have a flight director installed with an autopilot, but nearly all high-end autopilot systems either come with one or will drive one.

It also means that if you don't see that little snuggly picture on your AI, then your autopilot is either not engaged, or is not able to control the airplane to the attitude required. That "not in sync" picture is something that should get a pilot's attention in flight, particularly if he thinks the airplane is flying itself.

So a flight director is a good way to monitor the autoflight system. It can also be used to tell the pilot how to fly with the autopilot system (the servos that move the control surfaces) disengaged. It's a lot easier to fly an ILS approach by hand in crappy weather with a flight director in approach mode, because once you're established on the course, you can adjust your instrument scan to focus primarily on your AI, and you don't have to check your nav instrument as frequently. Just keep the snuggly picture, and mind your altitude and airspeed.

When I fly in real life, I won't fly in serious weather without either a copilot or a working autopilot. A flight director, like an HSI, reduces workload and is a big plus in my book