I confess to being rather bored by all this poring over and implied criticism of the aircraft systems. It seems that one Radio Altimeter failed - so what?
Commercial pilots are all required to hold an Instrument Rating. This means being able to fly the aircraft solely by reference to instruments. To do this, one develops the ability to scan across the instrumentation - attitude, speed, altitude, heading, back to attitude, etc. Especially on any approach - be it manual or automatic - a professional pilot should maintain that scan. This where the first indication of something unusual will be apparent. If it is manual flying, a manual correction is made. If it is autopilot flight, the automatics may need adjusting or, if there is a serious discrepancy, even disconnecting. Either way, a necessary correction to the flight path must be effected. This is what professional piloting is all about.
The idea that the pilot is simply a bystander to the electronic wizardry and only gets involved when the automatics provide a warning is absolute nonsense. There may be need for software criticism in order to improve its performance but do not let us overlook the fact that the pilot is in charge of the aircraft, whatever the automatics are doing - or trying to do.
Piloting comes first - automatics may help the pilot but are subsidiary to his/her primary function. Pilots are responsible for flying the aircraft. They may indeed use the automatics but then it is essential that they should watch the automatics to ensure they deliver the required aircraft flight path and performance. Failing to do this is nothing less than professional negligence.
JD
