blueloo I agree with captplaystation: never once going through turbulence have I thought of ACARSing ops to let them know its bumpy. Why would you? It doesnt achieve anything. ... Seems very bizarre.
It doesn't seem bizarre to me at all. Giving met PIREPs of severe weather conditions that could affect other aircraft (turbulence, ice, etc.) should not only be considered a professional obligation, but mandatory in some during some ops, including crossings.
This ACARS message from the AF pilot that reported they were experiencing "hard" turbulence came 10 minutes prior to the auto-ACARS mx messages
was one of the first things brought to light on this thread which quickly drifted off into lightning-and-techie talk with great abandon. This info isn't "new", and it's easy to imagine where a bad situation got worse with regards to turbulence and convective activity if their hands got full.
If the aircraft had slowed to Max Turb Air Penetration speed, someone else pointed out that at 35,000 with it's probable loading at that point for an 11 hour flight there existed approximately 15kts between Max Turb speed and clean low-speed cue, and only 25 kts between Max Turb and Low Speed buffet. NOT a good place to be in with anything more than moderate turbulence.
I assume the pilot (if he thought the turbulence severe enough to report it) would also have slowed to Max Turb Air Penetration Speed so things on the aircraft didn't begin to break, which puts it closer to the low speed buffet boundary and at FL350 with heavy weight, unfortunately it becomes more difficult to accelerate out of a gust/shear/convection-induced deteriorating low-speed condition due to relative-reduced engined performace.
Trying to maintain q-corner limits at high altitude while experiencing severe turbulence and updrafts/downdrafts of varying amplitudes can be an impossible situation for the A/P, or the pilot when the A/P disengages due to an exceedence of one of it's pitch/roll/etc parameters. What I gather from the Airbus drivers here, an out-of-parameters A/P disengagment such as would happen if the aircraft were being pitched or rolled past A/P limits will revert the flight controls to Alternate Law, which means hand-flying with no FBW stall protection or limtiting to half/low bank even at FL350. Please correct me if I'm wrong.
The greatest danger of high altitude flying ANY (Airbus, Boeing, whatever) aircraft through severe turbulence isn't that the aircraft will break up and lose control, it's that it will lose aerodynamic control and perhaps be impossible to recover from if it begins breaking on the way down or can't exit the severe conditions. Then the issue of engine-flame out looms large. In jet-upset incidents, engine flameout can come early and without engines electrics and pressurization are also suddenly added to the largest problem of re-gaining and maintaining aerodynamic control.
The fact that there were reports that little or no lightning was detected in the cells the flight track was shown going through or near points to the worse possibility it may have entered an area of developing cells which are where the most severe updraft and airmass convection is taking place, and least detectable moisture for the radar to paint. Aircraft have deviated themselves into a corner this way when snaking their way between cells and into "soft spots" and finding a developing cell instead of avoiding the entire area because it's too dynamic and unpredictable, or not visible due to it's imbedded nature or at night.
Mature and dissipating cells emit the most lightning, and attempting to (or inadvertantly) flying above a developing cell is a non-option, since the updraft turbulence rises to a mile or more above it's visible top.