The Achilles Heel is Ice, to which all three are equally vulnerable, so using more than one is not only expensive, it's dangerous. Why? Because to reject one and then look at another is prolonging the loss of reads, by definition. Placing them on strategic points on the nose is meaningless. Turbulence is not an issue, they are not designed to be resistant or sensitive, in a functional way. The only solution is to use one, or another or two of different manufacture. That may mitigate the vulnerability, so why just one PITOT at all?
. The siren song is "redundance". "Simultaneous" failure is not unexpected, it is PREDICTED, which leads us to the fatal programming. The computer is programmed to rely on the possibility of a combination of probes being reliable, should one become an "outlier". So it reads and computes.....GARBAGE.
By definition, if not by trial or test...All the while, the a/p soldiers on, the pilots are unaware, and unprimed for a worsening situation whilst the computer hogs precious time and calm from the crew....
So for the false security of "redundance" the solution is anomalous design. Sensing systems that are different in approach design, and isolated from the problems of the other, by design, raising the reliability many fold, and eliminating parallel failure of identical sytems. With three same, Each combination of the six available to the computer is no more reliable than the other, in the midst of fail.
What to do? If the a/s is not consistent with other systems performance (and comparing them is not easy, but certainly possible), REJECT IT> ALL OF IT, INSTANTLY.......Trying to hang on to a failing system is ignorant, imo. And I have shown how if one fails, the others will, don't pretend they are different, and can somehow be reliable when they won't.
PJ2 has me convinced that UAS is not a serious problem and I believe....
But it is potentially fatal when it is treated as an emergency first by the flight computers, and then by giving it to to the crew...with controls alterations, etc.
At the first suspicion, reject the air system.....And keep the aircraft in NORMAL LAW, Don't make a mountain out of the molehill. A/P quits, the pilot flies Pitch and POWER, and soon, the AD returns. Or, with anomalous design, use it as with the Thales, as a dependable grouping, not a triple failure...
An excellent time for the crew to demonstrate proficiency in what we are told is a non-event. That will make Machinbird happy, because he is right, some real time challenge is what is indicated to bring the proficiency up a notch.
alternate Law? for UAS? Why? The builders and owners don't trust the pilots anyway, why make it harder on them? Just so when the a/c STALLS< it can be reported it was not in NORMAL LAW when it STALLED? If the protections are hot S... why not leave them in, lewt them earn their keep.
Last edited by Lyman; 1st Jun 2012 at 00:12.