Calculation of Mach
DJ77 (#1833), thanks for your view. Whilst the Wiki references and the descriptions of mechanical instruments (and some ADCs) add credence to the view that TAT is not required to calculate Mach, I recall that temperature is in the root of the equations.
Mach is the ratio of speed at a point to the local speed of sound; the latter definition requires temperature. As has been shown, suitable manipulation of equations can reduce the measurement requirements to pressure / pressure difference for mechanical solutions, but IIRC this involves small errors or a look up table.
However, in a digital system, where programmers might be reluctant to use resource sapping square root calculations, alternative derivations of Mach may be used.
Thus, with open mind, the question is; how is Mach calculated in the A330 ADC?
CONF iture (#1825), info noted. However, with continuing open mind, it has not been established that 7000 ft / min is a real velocity or just that which was recorded (displayed). It appears that the aircraft did climb, but to what altitude and how fast might be poorly defined. Note that VH-EBA ‘descended’ suddenly 300ft, but this was only the recorded indication.
Considering a highly dynamic situation in AF447, with many parameters ‘failing’ or outputting erroneous values it might be difficult to draw any conclusion as to what the airaft actually did, perhaps excepting AOA, e.g. if the speed altitude anomalies were partially restored, how might the VS calculation account for these sudden changes (VS is an inertial / airdate mix?)