thermostat;
There is no evidence that AF447 was flying "through a CB". There is often (but not always) some turbulence associated with cloud but the levels of vertical 'g' shown in the traces are not significant in terms of "CB" penetration...they're pretty ordinary levels. I've seen much worse, in cloud and clear air.
Before the conclusion is drawn that the statements below advocate "flying into/through thunderstorms", some appreciation of the entire issue of weather and radar-use is required.
On the day of the accident as part of the initial responses on PPRuNe I posted a long discussion on the use (and abuse) of radar,
here.
One of the first principles of the use of any radar by flight crews is to know that it does not paint ice crystals, therefore if one cannot see over-hangs or thin cloud composed entirely of ice-crystals, (almost certainly the case here), one cannot avoid flying through such weather, nor is avoidance always necessary. It depends more on the potential for turbulence than it does avoiding "all cloud", (FYI, all cloud above the freezing level is ice crystal; one does not/cannot avoid
all cloud, ergo one cannot avoid flying through ice crystals).
The problem of momentarily blocked pitot tubes is extremely rare. Appendix 7 of the BEA Second Interim Report, which see, lists the events which occurred to Airbus. I have had such an event but on a B767 so it happens but given the millions of ice-crystal-cloud-penetrations that occur each year without result, "avoiding all cloud" isn't realistic. Clearly, avoiding all CBs is mandatory but that is well understood and the techniques for avoidance known.
Hello HN39;
If I may be forgiven as I know this has been discussed many times in previous threads, but for the benefit of those who may not have come across the discussion, regarding the UAS Memory items the A330 Flight Crew Training Manual states, in part:
PART 1: MEMORY ITEMS
If the safe conduct of the flight is affected, the flight crew applies the memory items. They allow "safe flight conditions" to be rapidly established in all flight phases (takeoff, climb, cruise) and aircraft configurations (weight and slats/flaps).
The memory items apply more particularly when a failure appears just after takeoff. Once the target pitch attitude and thrust values have been stabilized, as soon as above safe altitude, the flight crew will enter the 2nd part of the QRH procedure, to level off the aircraft and perform trouble shooting. This should not be delayed, since using the memory item parameters for a prolonged period may lead to speed limit exceedance.
PART 2: TROUBLE SHOOTING AND ISOLATION
GENERAL
If the wrong speed or altitude information does not affect the safe conduct of the flight, the crew will not apply the memory items, and will directly enter the part2 of the QRH procedure.
Note that the FCTM makes it clear that troubleshooting,
"...should not be delayed since using the memory item parameters for a prolonged period may lead to speed limit exceedance."
For others, (as I believe HN39 knows this), a pitch attitude of 5° at FL350 results in a climb of about 900 to 1500fpm with commensurate very gradual loss of airspeed/energy. While this doesn't lead to a stall, any pitch attitude higher than 5° will result in a loss of energy, a 15° pitch attitude, which is unheard of in a transport aircraft at cruise altitude, will rapidly lose energy and airspeed as seen, thus the FCTM admonition to get the QRH out quickly and set pitch/power according to the tables.
The memorized items never call for a 10° or 15° pitch attitude but the attaining of such attitudes may not have been intentional and may be the result of over-controlling; - there was an almost-instant rearward stick movement to 10°+ with a commensurate pitch attitude achieved of about 12° initially, going to 17°-18° within about 30" of the UAS event.
If one changes pitch attitude and/or power from what was stable flight prior to the UAS event, except for using GPS groundspeed as indicated in the QRH checklist (below the memorized items), there is no way to tell how much energy is being lost with higher pitch attitudes, and one will quickly lose "where one is" in terms of airspeed/energy levels, so it is urgent that pitch/power be set quickly if one is going to alter pitch attitude at all.
Part 2 of the QRH Procedure looks something like this:
In my opinion as a (retired) A330 captain, the "safe conduct of the flight" was never an issue with regard to AF447, (and wasn't with all other similar UAS events).
However, "safe conduct" is a subjective, not objective decision-point in a critical drill/checklist and I think that is a problem that can lead the crew into an inappropriate and unnecessarily quick response.
A loss of airspeed indication is not an emergency, nor was immediate action required, especially of kind executed here which was uncoordinated, unilateral actions (meaning the absence of the use of SOPs) by the PF which went unchallenged by the PNF.
As discussed previously, all the crew had to do was to maintain pitch attitude and power setting as per the UAS QRH checklist while the abnormality was announced by the PF and the QRH called for so that precise pitch and power settings could be determined. There was no need to set a different pitch attitude at all.
I think this is partly 1) a drill/checklist problem, 2) partly a training problem and 3) partly a cockpit discipline problem.
1) the drill/checklist is poorly-written and confusing as to correct response, 2) their UAS training was done quite some time prior to this event on an A320 simulator, with the UAS occuring right after takeoff (requiring TOGA/15°) and not at cruise altitude which didn't require any action at all as the "safe conduct of the flight" was not in question, and 3) the cockpit discipline matter has been thoroughly discussed but there was a leadership-followership issue which was (and still is) a problem when two F/Os are in command of the flight, and the captain did not address how drills would be handled.