Hello there,
I understand the risk underlined in the above Wired article:
- both the Pitot ram tube and its drain freeze, hence the airspeed derived from this compromised Pitot becomes an increasing function of the altitude,
- the flight enveloppe protection laws tend to increase the altitude if the airspeed increases too much
... and the interaction between these two phenomena makes a diverging control loop (if there is an altitude perturbation, say an increase, the airspeed increases too and the protection law commands an increase of altitude, etc...)
But in the AF 447 case:
- the early left PFD and the ISIS airspeeds inconsistency was only 1 min and the flawed airspeed does not seem overestimated but largely underestimated
- the flight protections (high speed prot) are lost in ALT2 triggered by a NAV disagreement
- the maintained NU inputs are the PF inputs
So how the Wired hypothesis can be applied to the AF 447 case ?
Hi Hyperveloce,
Yes, on reading the article I agree with your comments. The aircraft was not climbing prior to Alternate Law, and all subsequent NU inputs were from the PF's controls (that's pretty clear from the BEA report).
It worries me that this guy is (supposedly) a captain, he appears to have less understanding of this case than many of the 'punters' he openly dismisses.