Originally Posted by
gums
The scenario deeply disturbs me, and not just because the crew didn't turn on the heaters. The probes could have frozen anyway or ice crystals in the lines could have made things crazy. Oh well.......
Unfortunately, to me it sounds like typical swiss cheese hole scenario:
1. Airplane type has manual pitot heat (first hole)
2. Tired crew forgets to turn them on (another hole)
speculations:
3. Pitots start freezing at worst time (climb-out, going through possible precipitation, third hole)
4. *Indicated* airspeed starts declining, pilots do what pilots tend to do: keep speed alive. "Speed is life". Full power and stick forward to regain the airspeed. "we do not want to stall"
5. Being on climb out, there is very little time and height for crew to recognize the underlying issue. A/C overspeeds. Nose is tucking down (or Ukranian FBW is doing funny things based on unreliable speed input) and stick starts to loose authority. Lot's of alarms are sounding (I bet stall alarm was blaring at the same time as A/C was overspeeding, adding to confusion).
6. At low height, there is no time to regain control and A/C augers in.
FBW or not, all kinds of bad things can and will happen with unreliable airspeed if you are caught in bad moment
