Old Engineer:
Thank you for your post !!
I think we've all made it CLEAR to non airbus / non ISIS familiar colleagues (BOAC and others..) that the ISIS is a STBY / back up instrument independant from ADIRUs as a SOURCE of displayed flying DATA.
1. Is an inflight erroneous reset blocked by disagreement of ADIRUs 1 and 3? Or otherwise?
No idea. But I wouldn't think so. It's independant ! The inflight reset is made in case of ATT flag on the ISIS.
From FCOM: ATT flag (red) on ISIS appears when attitude data is lost, the red ATT flag appears. ATT RST The attitude indication can be reset by pressing this pushbutton for at least 2 seconds. The aircraft must be level during this procedure. During the reset time (approximately 10 seconds), the "ATT 10s" message is displayed on the screen. This pushbutton is also used to realign the system, if excessive aircraft movement is detected during the alignment phase.
2. Does crew training include instruction on how, when, and when not to make inflight reset?
well, not me....
3. Does crew training include how and when to bring the ISIS up for flying, if needed?
3a. Or how, when, and why it becomes the instrument for flying, if automatic?
When attitude/altitude/airspeed reference are lost from tripple IR failures, tripple ADR failures, blank DUs etc... (these are no longer available on PFDs basically)
4. Does crew training include mention that all the ISIS displays are normally accurate (IMO), except that IAS and FL may err due to probe icing?
Yes !
5. Is there any SIM training with ISIS as the only flight instrument? with its ILS feature?
Not on a recurrent sim training basis...maybe it will be in the future now !
6. [I omit mentioning again all the proper flying procedures covered by others.]
7. Does the QRH cover all this? Can or should it be memory trained?
Flying by reference to stby instrument in general is not a memory item. it's pretty much a reflex to go to the available information remaining. Nothing in QRH re:ISIS.
8. Are electric power issues covered? LCD screen readable with flashlight if necessary (that external 5vac)?
electric power: as said, DC ESS BUS + Hot Bat1 backup.
Yes you could read the LCD with the flash light.
And a final question:
9. If an ISIS FAIL message is generated for ACARS due ADIRU input fail (see above), does it blandly repeat on the PFDs in just those words? Can we tell from the ACARS? (I know... not easily.)
There is no Flag on PFDs concerning ISIS. Failures/errors pertaining to ISIS are displayed flags on the ISIS LCD itself. Nothing on ECAM either,
ACARS message re:ISIS, we need a decode. Could be the Airspeed flag if STBY pitot has a problem, as simple as that.
By the way, NAV ADR DISAGREE can come up with 2 erroneous AOA data as well (ADRs).
OK. My opinion is that is all else fails, the ISIS is available to maintain at least the attitude of the A/C.
I think we can leave the ISIS to rest now ! no ?
