A320 ADIRS 3 minutes before shut-off

[Skipping Classes]

Hi,

All experienced A320 pilots know that you should wait for at least three minutes after the aircraft complete stop before switching off the ADIRS.

If you don't - you will most likely get an align problems due to incorrect position memorized by the ADIRS at shut-off and possibly will have to shutdown the aircraft completely to reset everything. (Sometimes pulling
the ADIRS circuit breakers for 3 minutes helps too)

All this confirmed by experience yesterday ;-)

Now the question is where can this 3 minutes delay before shutdown can be found in the FCOM's?

The only reference I can find is US Airways unofficial Airbus A320 Notes, saying:

"Note: DO NOT move aircraft during alignment. Wait 3 minutes after aircraft
stop to re-align or turn off (PH 3.4.1, 3.16)"

FCOM 3.4.1 and 3.16 does not contain anything relevant to this topic.

Any idea what is this PH 3.4.1 and 3.16 are?

Thanks in advance and remember not to shut-off the ADIRS within 3 minutes after a/c stop! ;-)

Cheers,

SC

[Sputnik80]

ADIRU DOzing

I had a case of losing ADR1 inflight and no ECAM warning or warning light on Overhead panel came up whatsoever.All ADR1 instrumentation on CPT's side were lost however.Using CPT3 switching ,all this was restored but it still baffles me that no ECAM actions were shown to do this.Back home at base an Avionics Engineer (after I explained to him what happened ), told me that there was no fault whatsosver on ADR1 (after doing a diagnostics test)....what happened was that the ADR was dozing and switched itself off automatically.Any ideas why nothing is mentioned in the FCOM's?

[TyroPicard]

I've never heard of waiting three minutes, and it's not in FCOM....
But you only switch them off at bed-time and with luck someone else will fly it next....
It takes a while to get to them on the checklist anyway - if you are doing it right...

TP

[Bad to the bones]

3 minutes wait for IRS

On aircraft equipped with LITTON IRS the ground speed check, must be performed after 3 minutes aircraft stop (this is because the Ground Speed resets to "0" after 3 minutes), may be that is the question.
However it is only to compare the Ground Speed readings between the IRSs, to find any abnormal reading, not for shut Off.
This is described on Airbus SOP.

[a320dude]

It refers to the USAirways Pilot Handbook which contains systems and procedures for the different aircraft in the fleet.