@BOAC
May be because PF was really concerned with "Overspeed"...
2.1.3.3.1 PF’s reactions
On the other hand,
in the absence of airspeed information known to be reliable, it is possible that the
PF thought that the aeroplane was in an overspeed situation, notably due to his
interpretations of several clues:
ˆ The aerodynamic noise,
ˆ The buffeting, that he might have interpreted as being due to high speed,
ˆ The speed trend arrow on the PFD, which at that time indicated acceleration.
He reformulated his impression
a*few seconds later, combined with an attempt to extend the speedbrakes.
Other factors which may have prompted the PF to fear an overspeed situation were:
ˆ The display on the ECAM (max speed 330/.82) combined with the reconfiguration
to alternate law which may have been read;
ˆ The fact that, in cruise, the upper red strip on the speed tape (MMO) is about ten
knots above the current speed, whereas VLS is barely visible at the bottom of the
tape (thirty knots less);
ˆ The dangers associated with overspeed situations embedded in the collective
consciousness of pilots.