B777 Airspeed Unreliable

[FlyingGourmet]

Hey Folks,

in the FCOM 2 it states that the GS indication on the ND comes from the ADIRU but in the Airspeed Unreliable NNC it says that the Ground Speed is reliable. From there exactly comes the info and where can I read it in detail?

thanks

[8che]

Hey Folks,

in the FCOM 2 it states that the GS indication on the ND comes from the ADIRU but in the Airspeed Unreliable NNC it says that the Ground Speed is reliable. From there exactly comes the info and where can I read it in detail?

thanks


Think of the ADIRU as the AD + IRU.

With unreliable airspeed the AD part is affected.
It is the IRU part that delivers G/S and so remains unaffected (to the required extent at least)