Machinbird point above reminds me of somethinng I have pondered in the past:
Often when reading failure reports the root (or major contributing) technical defect is shown to be something that would have been detected had the same people reviewed the mission in advance.

This has led me to wonder what would happen if the failure board had convened before the mission was launched.

A number of plausible failures have been identified in this case, rather proving that one was the cause before fixing it why not fix all of them, at least those that carefull analysis show unlikely to have unintended negative consequences.

- same age - same corrosion - same maintenance)

Also incredibly unlikely that 2 AoA sensors would tell the same lie ... ? (See Perpignan)

But no need to be inside. For the 13 events studied by the BEA, the crews reported not observing any significant radar echoes on the chosen flight path but to have identified active zones nearby or lower, which is also noted in a study by Météo France on these events undertaken at the request of the BEA.

Sensor validation,

It is possible to tell which is a sole correct pitot reading, as long as you go back to the very basics & fly pitch & power, to corroborate its readings.

If you ever have spare time in an airbus sim try climbing from optimum to somewhere near max alt with blocked pitots. The flight control laws lead to pretty interesting results!!

Right Way Up:
Are you referring to the Vmo/Mmo protections, or something else??
This is a bit different than a conventional bellows/aneroid type airspeed indicator. The pressure would still be trapped (unchanging) between the pitot blockage and its associated pressure sensor, but the static pressure sensors would be dropping together and would likely pass validation. If the system merely calculates delta P to get the airspeed, then the airspeed would wind upwards pretty evenly between the 3 ADR systems. Normally the pitot side pressure would be dropping if you climb at constant IAS, but would be matched by an equivalent static pressure drop.

The constant pitot pressure, dropping static pressure situation resembles an acceleration and should be amenable to some sort of validity check, because in real life it would be hard to accelerate as you climb, particularly at altitude. At some point, you exceed the aircraft's performance capability.

Machinbird,

As you climb indicated speed/mach will increase, the autopilot/flt directors will command an increasingly high rate of climb to cater for it. With a high rate of climb and with actual speed reducing fast, the increased indicated speed will take the aircraft into the overspeed protections. Just when you want to reduce pitch to normal levels to avoid the stall the aircrafts protection system will stop you from lowering the nose.

Thank you Right Way Up. Another variation on the Vmo/Mmo protection pitchup stall entry.
Looks like Airbus needs to rethink the concept of how they protect against overspeeds.
Were you introduced to this in the simulator, or do you know of a flight incident?

Unfortunately without validated WAAS, you don't know if that GPS update is within 10m or 1000m off the mark.

Machinbird,

In the simulator. As far as I know there is no "known" inflight incident.

To a human pilot maybe, but apparently not for the auto-pilot

The classic case where blocked pitot tubes allow decreasing static pressure due to increasing altitude appear as increasing speed. Clearly a significant danger on climb after take-off, which has had fatal results, and an early action of the unreliable speed QRH is to level off.

By why would they be deliberately climbing inside a Cb, no way could they overfly - would conditions be expected to be better at unauthorized FL370?. How about a relatively warm humid low density updraught?

The crew could have thought they had left the weather behind, the captain was released by his first officer, which, after having taken stock of the flight’s progress, decided this was a good point to step-climb to FL370.

However, in my opinion the condition of the RTLU doesn’t fit in this scenario. (see mm43#1669 on p.84 and Machinbird #1681 on p.85)


regards,
HN39

Right Way Up:FCOM 1.27.30 ALTERNATE LAW
Are you thinking on the possibility of an attentive movement of the crew to change the Laws, from Normal to ALT via switching off PRIM1 and SEC1?

Aquadalte,

My input was from an A320 point of view where in normal law in case of overspeed: (from A320 FCOM)

.

So even though you are getting into the low speed regime, the aircraft thinks you are in an overspeed and normal law will not allow you to lower the nose.

If I understand you right you suggest the only initial way to get out of this is to dumb the aircraft down to ALT law. Which I would agree with.

Definitely such move would require a clearance before proceeding, even if a step climb was planned on the flight plan.

Hazelnuts,

Aquadalte's quote is regarding the aircraft response in alternate law where your quote is regarding normal law.

Thanks Right Way Up, I misread aguadalte's post and have deleted my post.

regards,
HN39

transition modes with no protection?
 

HazelNuts39:I remember reading the preliminary accident report of the Crash-aerien 30 JUN 1994 d'un Airbus A330-321 F-WWKH - Toulouse-Blagnac Airport where it was stated that, one of the contributing facts for the crash was "the absence of pitch attitude protection in the autopilot altitude acquisition mode [that] played a significant role." [see here]

Since then, I have always kept the idea (although I don't remember having seen it written in the FCOM), that during transition modes (like ALT*, ALT CRZ* modes) protections are lost, even in Normal Law.

Could anybody lead me to the Accident Report of that particular flight? (Can't find it in the web)
Could it be that, after that particular accident, some sort of upgrade was made to Airbus aircraft flight control laws (and that is why I can't find any clues on the subject in current FCOM's?

(please don't be mad at me if I don't reply to your help on this one, soon. I'm flying to LAD this evening and internet there is so slow...:zzz:)

Overspeed
 

I am not sure how relevant this is (if at all) but there was an incident in 2000 with a UPS 747-200F (N520UP) which took off from Dublin Airport on a post maintenance test flight.

The aircraft took off with the static drain port caps missing which resulted in the aircraft exceeding its speed limitations due to under reading pitot-static instruments caused by cabin pressure being sensed. The aircraft suffered flap damage caused by the excessive speed.

bizdev

Preliminary report F-WWKH
 

There is a copy of the préliminary report for the Blagnac A330 F-WWKH (french only) :

Rapport Preliminaire - A330 Toulouse
I think there must be a final report somewhere which has been made by the French BEAD (not BEA), the D is for Defense as the report was made by the military due the flight being a test flight.

Yikes, Right-Way-Up

Shades of Northwest B727 on 1 December 1974.


Goldfish

Very much so goldfish.

The only difference is that in an Airbus if you do recognise the problem once in the "indicated" overspeed it will not let you lower the nose until you are in alternate law either via "abnormal attitude" or you force it into alternate law.

I think Airbus should look at some sort of system that will compare actual performance at altitude compared to calculated performance with the idea that the aircraft will automatically drop into alternate law if there is a large discrepancy.