If I read that Vanity Fair article correctly, it suggested that at certain points the EFIS did not display correct values because the jet's pitch, and/or roll exceeded what it could measure.
I had assumed that like a fast jet panel, an airliner EFIS would display values even if they were way outside the recommended operating envelope.
So if you are 60 degrees nose up (extremely high alpha) will the EFIS in an airliner simply peg out at around 40 degrees nose up?
If - apologies to Tex Johnson - you flew a barrel roll in an A320 for example, or were able to fly a loop would the EFIS display flip and display inverted pitch or roll values as it does in a jet fighter, or is it simply not programmed to do this, because it's not expected, and therefore would be an unnecessary complication/and or cost to add?
AF447 did not reach an unusual attitude at any point. The only parameter that could have triggered the unusual attitude law would have been the 45° AOA.
The EFIS is certainly capable of displaying the
full range of attitudes (having done them in the simulator).
However, there is some anecdotal evidence of loss attitude display in similar incidents, detailed in my book. AF447: "we have not more usable displays" (certainly open to interpretation)—which AB says refers to airspeed and vertical speed indications since there is no good explanation why attitude should be lost in such a situation, and a Mihin Lanka flight whose pilots "reported the loss of both attitude displays on their Primary Flight Displays (PFDs) for up to 20 seconds." It is for this reason that the BEA recommended that there be some visual recording of what is actually displayed on the EFIS, instead of only recording the raw data.