FLIGHT DIRECTOR

n9xv wrote:

I'm not quite sure I understand the "practical" use of the flight director. I thought when flying manually (AP off), it would indicate the correct angle of bank for a standard rate turn. When AP is on, it always seems to use about 22-degrees of bank unless your at a VERY slow airspeed. I'd greatly appriciate any light on the subject.
Kevin

The standard bank angle used by the FD is 25 degrees, it does not use the standard rate of turn.

ok - but whats the significance of the command bars being visible or not? I thought the command bars represented the "ideal" result - for a given control surface input - which you follow by "inserting" the wedge (representing the airplane) into the command bars.

I think what I'm trying to understand is,

- what are the command bars "commanding" you to do?

The command bars are where you place(fly) the aircraft symbol of the attitude indicator in order to hand fly the aircraft via inputs from the flight director system. The flight directors commands come from how you've set the autopilot system, vertical speed, altitude, nav, approach mode. The signals are the same as what it sends to the autopilot except the autopilot is not on. It helps the pilot fly more accurately than just hand flying without any guidance at all(raw data). When you fly raw data, you have to judge when to lead a turn on to a VOR radial, how much pitch is required to maintain a certain vertical speed and you have to manually maintain your attitude while on the ILS. The flight directors system does this for you, you just keep the aircraft symbol aligned with the flight director bars and the aircraft will fly correctly. Your arms are just replacing the input of the autopilot but the system guides you. It just makes it easier to fly. If you want to fly completely manually, there is a switch to remove the bars so that they don't distract you. When the autopilot is on, the flight director bars show you what the autopilot is about to do, you may need to intervene if it's not correct. If the autopilot was inoperative, flying with the flight director system takes some of the work load off of the pilot instead of completely hand flying.

Thats interesting! I have'nt been able to get as clear an explaination of it as you provided. I'll spend a little more time with the FD scenario. Thanks!