ACARS time source question
 

Could anyone tell me where ACARS gets it's time source? Also can it be manually set?

Depends on the airplane, I would imagine. As to 'manually' setting, that also would depend on the source of the master clock. Some older and less sophisticated (electronically) aircraft still go by the captain's chrono while others have digital aspirations that put the master in an equipment rack down below with access sometimes granted via the FMC/MCDU. In my experience, UTC sources include GPS and dispatch uplink syncs.

I seem to be no help on this so far Chappy!
Any chance you have an aircraft type in mind?

ACARS time source question
 

Nothing in particular but if someone could explain the differences between manufacturers and ages of aircraft it would be of help.