787 altimeter inaccuracy
Just been made aware of (yet another) BAB for the 787 where the altimeter measurement differs between Capt and FOs PFDs because of an FCM fault.
Apparently this can cause altitude excursions of up to 1000ft (great in RVSM airspace...) and we have a new unannunciated checklist to play with.
The thing is, all the training material for the 787 says that air data displayed on the PFDs is voted single-source, so how can one side provide different data to the other?
Is this another "the pilots don't need to know how this actually works" situation?