Use a ‘systems’ viewpoint for greater learning opportunity. Consider the machine and human together as a system, which is within the overall operational environment.
Suspend judgement, not to look for cause or seek to blame. At best, contributing or influencing factors might be identified.
Preceding ice crystals events had successful outcomes. Why;-
Did the regulator depend on the apparent success of human intervention as mitigation until modifications were available, providing pilots have refresher training for flight with unreliable airspeed; yet qualified pilots are already trained. Refresher training viewed the human as a ‘threat’, something to be improved and checked; whereas the real ‘engineering’ threat was ice crystals.
In the same time scale some new engines / probes had similar problems with ice crystal conditions; there was risk of simultaneous multiple engine malfunction - loss of thrust.
In this instance the regulatory approach was to avoid the ice crystal threat, use the human as an asset, supporting advice to detect and avoid the threat, and increase distance margins; but not to practice flight without engines!
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https://www.skybrary.aero/index.php/...ations_for_ATC see further reading)
Additional training adds to the operational load; never enough time, ‘jump through the hoop’, Capts simulator demo / handling only. Did the simulation involve multiple ADC problems and display the other malfunctions, alternate control law, warnings and annunciations; or just remove the airspeed display. The latter easily identified as a speed problem, thus no real training for problem deduction and awareness, no link to the reality of the threat. Who choses the scenario, conducts the training, do they know why it is required; is it based on ‘evidence’.
Do operators require Capt handling for all emergencies, if so FOs might never get the ‘feel’ of a degraded aircraft. FOs only read the checklist - better imprinting the initial memory items - which may be first recalled when surprised.
Does simulator training focus on dynamic scenarios, because it involves aircraft handling, thus maximising simulator use, opposed to reading the alternative followup drills, which actually relate to the threat; checks only, no flying action required.
Should checklists have a conditional statement before boxed memory items. “If an emergency, then action memory items, or if not, use (read) followup items”. Who judges what is an ‘emergency’ situation, Capts or FO, different experience levels, perception.
Some drills for unreliable airspeed separate ‘failures during takeoff and climb’, from those ‘in level flight’; often differentiated as dynamic situations requiring memory action, or less demanding level flight. This requires two checklists depending on the flight condition. However, amalgamation to ‘simplify’ the QRH, needs a preceding check of the situation, which together with changed terminology - ‘emergency’, potential confusion.
All crew should be involved decision making - good CRM.
e.g. Capt, “With respect to the storms ahead, 15 nm left should be OK, what do you think?” Alternatively “What deviation should we make for the storms ahead.” It’s easy to agree with the first option, but the second requires mental engagement, assessment and judgement, by all crew. The latter aids experience and primes thought processes for later - a fast changing situation, particularly when the Capt is absent.
Why did one flight have a different outcome? It’s impossible to say, a futile search without knowing the crew’s understanding. Cause and blame are backward-looking, providing few facts on which to base learning.
Alternatively forward looking, considering possible influencing factors, and ‘what if’, might apply to threat scenarios not yet considered - those greater than 10^-z, which have been foreseen, but ‘don’t need to consider’, or the really unforeseen issues; “I don’t believe it”.
We can learn from hindsight, but only when turned into foresight.