Question for Airbus Pilots: ADIRS in ATT

[PTUinop]

Context: I am a flight simulation enthusiast (armchair pilot). This is about the A320 family. Might be applicable to 330 fam.

What flight control law would the aircraft be in if one:

1. Started from cold and dark
2. Not programme the FMS.
3. Not align the ADIRS and switch them to the ATT position
4. Takeoff

Thanks.

[Denti]

In the "you're facing jail time" law.

[PTUinop]

Thanks for the response. Could you please suggest where I could look in the FCOM to find this information?

[Denti]

I doubt you will find that in the FCOM, that case is simply not any kind of operation, neither normal nor non-normal. It would be criminal negligence and going against any SOPs to do something like that.

[AerocatS2A]

If you don't know the answer, why not just say so Denti?

[compressor stall]

It's actually an interesting theoretical question.

[Denti]

It might be, but please read the description at the top of the forum.

To be honest, with two IR inop or in ATT (ATT can be tried after a fault) you are in alternate law and with landing gear down in direct law, that can, however, only happen after failures inflight. All IR lost is actually not considered in the abnormal procedure design of the a320, there is no ECAM for that case, nor any QRH procedure. With all three IRs lost the aircraft is obviously in direct law.

There is however a procedure for a failure of all three ADRs, which is either fly the green if BUSS equipped, or use the ISIS (standby PFD) if not. Oh, and all three ADRs lost results in direct law as well of course. Which should be apparent by the general system design of the A320.

No sane pilot however would take off in that configuration, haven't even seen it in the insane 15 minutes at the end of each simulator session. Flying inverted? Sure, How to get there out of normal law without switching anything off? Great fun.

[Uplinker]

I don't know the answer, but once, having completely shut down for the night, we had to restart an A330 to re-position it on the ramp by about 30 meters, (don't ask! - it was a 'third world' airport, no disrespect to them).

The TRE I was with said we had to align at least one ADIRS otherwise we would not have nose-wheel steering. I have just looked that one up; the FCOM steering control schematic does not show an ADIRS being necessary, although a PRIM is, and PRIMs need to know ground speed, amongst other things, so he was probably right.
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