Re the stall discussion; ‘all warnings must be respected’, is generally true. Great care is taken to ensure that technology has a very low false warning rate for critical warnings – hazardous situations, but in some circumstances the crew are also alerted to an impending hazardous situation, e.g. TAWS - Amber alerts, then Red warnings. Crews, in normal circumstances are not required to, and should not attempt to identify ‘false’ warnings.
In conventional aircraft, many stall ‘warning’ systems have two levels.
An alert level is given before the aircraft stalls, e.g. 1.05 -1.1 Vs, where usually stick-shake provides additional awareness. Somewhat misleadingly, the majority of alerting signals are called “stall warning” (vice alerting), but the recovery action only requires avoidance of the approaching stall.
The actual stall (Vs) is defined by an identification signal (stall ident); often via a stick push which cues the full recovery action.
In aircraft such as the A330, there may be no requirement for one or both parts of a stall identification system, particularly where control/AOA limiting protections are used.
However, when flying in a reversionary mode – the loss of the protections, aspects of a conventional stall ‘alert’ are used.
AFAIK the setting of this alert provides the crew with information that they are approaching a stall and that ‘avoidance’ action is required (an alert). This is not necessarily stall recovery, just the alleviation of the impending situation.
I doubt that many crews either have or even those with this knowledge (as applicable to the A330) would be able to recall and apply it in such difficult circumstances – no display of primary information, unreliable airspeed, convective weather.
In the absence of specific training, any crew might well revert to old habits – basic training, a full-stall recovery.
In this, there may be similarities with the Colgan Air accident.
It appears that the specific combination of circumstances in this accident is very, very rare. Remove any one of the main contributions and the outcome could have been significantly different – note previous incidents.
The design assumptions about the use of alternative stall awareness, procedures for unreliable airspeed, and even the continued airworthiness status after reports of pitot problems were probably justifiable before this event; - after, now with hindsight, a change is required.