For the n-th time:
From the ATC's viewpoint, flight was proceeding normally untill the radar and radio contact was lost as the aeroplane was returning to land. Maybe I'm mistaken but I believe if some significant fault (and probe or ADIRS fault is significant) during acceptance test flight, flight is cut short and aeroplane is returned to maintenance, untill the time it's pronounced fit for another try. Blocked probes would result in anomalous readings immediately after lift-off, followed by prompt return.
Regarding the Perpignan accident, we're no smarter than we were three days after the crash.
Clandestino, do you mean Airbus rushed to publish a RED OEB just for fun ?
Whatever was written in it, it was published it because Airbus deemed it it necessary. If any aviation-related entity believes that non-acting has serious safety implications, it will act on the basis of high probability and not wait for certainity. OEB's can be withdrawn or ammended.
Now, to know if one simple (guarded) push button should be installed in the FBW Airbus in order to easily go back to the basic DIRECT LAW ... why not ?
Because pilots have their performance and limitations, too. If a pilot is so confused and behind the aeroplane that he allows it to enter protection, then he might start panicking and cut-out the protection that's doing it's job in mistaken belief that it's gone beserk. Mind you: no FBW protected aeroplane, be it Boeing, Airbus, Tupolev or Embraer, has been lost to stall or spiral dive in everyday operation yet. And protections are far easier to implement and more effective if you have FBW than classic controls.
That is not to say that protection makes anyone & his dog able to fly an Airbus. Staying out of protections still demands skill, concentration and foretought. And very seldom something goes seriously wrong and one ends up in altn or direct law and then Airbus needs the pilot at the controls as much as DC-3 needs it.