Double flight director switches

[chiswick72 145]

Hi guys,I just noticed the two Flight Director switches on the glareshield and I was wondering how they work.If you turn one on does the other switch auto engage? Or are there two seperate parallel flight director systems on the 747?Many thanks in advance!Armen at EGLLwww.veryquiet.com

[Guest dwinters]

HiI might be misunderstanding you here, but here goes...I THINK that each FD can be engaged separately depending on the pilots choice. ie. the captain can engage his/hers without the first officer engaging his/hers.As always correct me if I am wrong, but this is how I have come to understand it.David Winters

[Guest yawdamper]

When you switch one FD on the other one doesn#t engage automatically. (Most of the time both will be on, however). There is only one flight director system on the 744. If you first switch on the right FD then set modes, the left FD will show the exact same commands when it is turned on. Otherwise NTSB's reports would be twice as thick!The FD can also appear without the switch being physically in the ON position when you perform a go around.Cheers,Adrian

[chiswick72 145]

Thanks for the info guys!:-)Armen at EGLLwww.veryquiet.com

[Guest flybywr]

Actually, the B747-400 has 3 FCC's (flight control computers). These computers provide the data for the PFD displays. They can be selected on the source select panel for the fd's on the left or right side of the cockpit. Also, with the fd switches "off" the will automatically display when a "to/ga" switch is pressed if the airspeed is above 80 kts. where on the ground or in the air when the flaps are out of "up" position.I fly this aircraft (B747-400) as a Captain for a major USA airline.Kindly,flyby