A-380 probes
 

http://i25.servimg.com/u/f25/11/75/17/84/a380_p10.gif

On top of the nose cone, the 380 has 3 probes not seen on the other Airbus types. They look similar in shape to the usual AoA probes but are probably dedicated to measure the yaw ... ?

SSA probes.Providing additional informations for ADIRU calculation of the side slip.Shall improve confort on Aircraft with long fuselage.

Would they still allow intentional side slip ?

Those Side Slip probes each report their measurements to their applicable ADR part of the ADIRU. The ADIRU provide the SSA to the respective PRIM. The data provided is used in all sorts of ways. Slip in turn, slip with E/O, crosswind slip, Y* law calculations and a great many other ways. If the SSA data to one ADIRU is corrupt then that data is excluded. If two ADR's receive corrupt SSA data then all SSA data is excluded and the flight control law reverts to Alternate Law.

Would the crew be positively advised of such exclusion ?
In the eventuality of 2 SSA probes provide an identical but erroneous data, I presume flight control law will remain normal ... Are we aware of any ill effect such dysfunction would provoke on the airplane behavior ?

All monitoring relies on a voting principle whereby when one source diverges from the average value, it is automatically rejected.
As your questioning has now descended to the fanciful, I withdraw from the discussion.

'fanciful' ? ... How do you rate the possibility that 2 AoA probes tell the same lie and therefore silently discard the only valid one ?

As not likely with three independent systems.

It would be called common mode failure, for which the system will be designed against and the safety case would support.

We do quite a lot of thinking (i.e. engineering) when designing aircraft you know:ok:

Yeah, but AF 447 comes to my mind....

Typhoid, forget AF447 for now-that is still undetermined. Have you read the accident report for A-320 D-AXLA near Perpignan France? http://www.bea.aero/docspa/2008/d-la...a081127.en.pdf

I don’t doubt it a minute, but accident reports show that 'quite a lot' does not prove to be always sufficient. Unexpected scenarios can provide interesting challenges or surprises, and a designer just cannot imagine all the possibilities.

Every time another sophisticated feature is brought up, there is an open door for new surprises. Those new Side Slip Angle probes seem to achieve a lot through the flight controls, I think it is worth asking now what if … or we may have to learn it the hard way later on.