Originally Posted by
Ber Nooly
From the CAPE values (around 2000 J/kg) indicated by the model analysis I calculated MAXIMUM updraft velocities of around 55 knots. In reality, rain-loading of the updraft reduces actual velolcities by maybe 30-40%, but let's allow for some stronger outliers too. I still can't see 100 knots being possible, but that's a moot point at this stage.
I realize that I increased the amount of the updraft it was for simplicity of calculation. I still think that the more likely cause of the upset would be the coincidence of a severe updraft and a jump in OAT that would confuse the ADIRUs. If that was linked to sudden accumulation of clear icing from liquid water droplets in the updraft that could block pitot/static ports, then things could get very confusing for both the automatics and the flight crew.
Experts on the Airbus AIDRU algorithms should be able to give an idea on how they could react to:
1. Sudden OAT increase in cruise at FL320
2. Sudden loss of reliable pitot/static information (possibly associated with (1).
The response of the FMC to the AIDRUs could be added to a sudden updraft with a VS of let's say 5,000fpm (to use a value in line with your CAPE values). If the FMC initiated a 'protection' pitch up at the same time as the ambient air was lifting the aircraft at 5000fpm it might explain the apparent unlikely climb rates.