Dozy (re:
#201)
I'm aware that some terms used are not the proper ones, but being on an aviation forum I felt OK to use them as intended by other posters. Besides, english is not my mothertongue.
So, about logical/algorythm errors: let's look at them from the end-user point of view, i.e. the flight crews in the present situation. To be honnest, I don't think the "clients" (pilots) do care if the problem is :
- a hole in the specifications
- a implementation bug
- another type of bug
- an hardware failure
They see the outcome, which is that from a pilot's point of view, the system is illogical.
Back to "my" four points:
Point 1] (non-inhibition of the nose-up autotrim when stall warning is active)
You said: "I can foresee a couple of situations off the top of my head where that could be more dangerous than letting the trim run."
Well, I cannot. Could you elaborate, please? I did the reasonning with: "Would a pilot (provided he's aware & not mental) trim up when the aircraft is (near) stalled?" I could not see a single reason/circonstances where the answer is "yes".
About complexity: Yes, such a feature would add one more logical test. It's not a big deal in my opinion. And, more important, it doesn't seem a big deal to Airbus either because the NU autotrim
is inhibited in Normal Law when the pseudo equivalent of the S/W (namely: the AoA protection) is active (ref: FCOM A330). If they can implement it in Normal Law, the complexity argument is IMO moot in Alternate Law.
Point 2] (inhibition of the stall warning under 60kt IAS)
I would like to know if such an inhibition is present on other aircrafts, too. I'm afraid a lot more aircrafts than "just" the A330 do more or less the same, indeed.
Latching the S/W state with no AoA valid measure: Why not, but I'm not sure about the risks of a false positive, here.
Other way is perhaps to inform the crew (how: to be thought) that currently "AoA measure is invalid. Consequence: S/W inop". That far more simple to implement, and avoids the need to "assume" what the S/W state should be.
Point 3] (V/S switching source from air data to inertial (and back))
Yes, I'm sure the V/S source switched. There is such a parameter in the FDR traces : "VERTICAL SPEED SELECTED FROM ADR (1=ADR 0=IR)"
The V/S recorded (and I assume, displayed during the flight) is "erratic" when ADR is the source, but "stable" when IR is the source.
When the PF said "J’ai un problème c’est que j’ai plus de vario là" (02:11:58) that's ~10-15 seconds after the switch to ADR source, and the beginning of the erratic values...
Note that at the same time as the V/S first swith to ADR source & display erratic values, other parameters go erratic too: CAS, AoA, FPA... and the S/W stops. So I agree that the V/S go erratic at the same time the stall is well established.
Point 4] (non-inhibition of the F/Ds when an UAS situation is detected)
I've perhaps written to quickly about that one. If the F/Ds indeed are inhibited, that's good. The logic hole I saw there is that while A/P and A/THR are dropped (i.e. the crew must re-engage them manually if they want them back), the F/Ds seem to just go flagged, but come back "from themseleves" when the conditions seem back to good: Would it not be better to let the crew manually re-engage the F/Ds, having assessed the which data are good and which are not?
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jcjeant (re:
#202)
One cannot hope a 100% reliable sensor. One can (must) work to go as near as possible to the 100%, but must know he cannot obtain it.
My position is one cannot advocate for dropping automation until a perfect sensor is available, unless the goal is to drop automation itself without saying it.
On the other hand, yes there seem to be problems with the certification criteria regarding the probes. If proved, then the industry should work on that. But by no mean calling to a "stop" until perfection is reached will be of some help IMO
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Originally Posted by
NARVAL
The A330 was modified after the crash (those at air France anyway) to have a « dual Input « alarm when both pilots act on the sticks at the same time. It did not have that alarm on the night of the accident.
I don't know what/who is your source on that, but based on the CVR transcript from AF447, it's wrong.
I'm not aware that TOGA is now
forbidden at altitude?
I'm aware, on the other hand, that the stall (old) procedure which was good only to an approach to stall condition is now reworked so that it's good in a stalled condition too, implying the "lower AoA" rule, most important/first action.
