I have a question.
As a mere engineer, I understand the problems of high altitude flight with the proximity of stall speed and overspeed.
With the known problems of pitot icing (though I have never seen it) why don't you pilots just stop flying so high when there are storms about? Would it not be easy to mandate a descent to a lower FL where the speed range is greater so you have more time to react if something goes wrong?
Yes I know it costs money, but so do crashes.
Steve,
the answer to your question is that the preferred method of CB avoidance is lateral rather than vertical. Best of all one avoids a whole system but when this is not possible (as is frequently the case) the method is to find a route between individual cells, not penetrate any of the cells themselves. Often this is easier when higher because the gaps between the cells
are greater. Also many CBs do not reach cruise altitude. Sometimes lower altitude can involve worse weather.
My own experience is that operating at normal optimum altitudes is satisfactory provided that adequate lateral separation from CB can be achieved. Careful monitoring and readiness to intervene on speed and thrust are part of the process.
The issue of probe icing is one I have not encountered, nor I would guess, have most readers,and it would appear to be type specific to A330/340. It would also appear, judging from the reports from previous contributors, to occur in specific circumstances, notably layer cloud around the CB e.g.the anvil, even though the CB itself has been avoided.
It is of course true to say that if airspeed indications are lost, lower altitude does give a greater range of speed availability, therefore the crew's task is easier. In all cases judgements have to be made according to the circumstances.