ACARS OOOI Status

[Will]

I'm doing something that resets my ACARS to the PREFLT INDEX and changes the OOOI times to "****z" and I can't figure out what I'm doing.

I will land, and park the aircraft, shut down the engines, and open the doors, and then within just a few seconds the ACARS resets to PREFLT. On the ACARS OOOI STATUS page, the flight number stays the same but all the times are replaced by "****z" and the DEPT/DEST is replaced by the destination airport twice, like this:

DEPT/DEST
EHAM/EHAM

I haven't touched the FMC at all; this means I've not entered a new route, no new flight number, no new DEPT or DEST airports entered. RTE 2 is empty and RTE 1 becomes empty after landing.

Are there any other triggers that would switch ACARS from postflight to preflight?

I'm asking because it doesn't even give me a chance to jot down the OOOI times; they are erased literally within 1-2 seconds of the doors opening.

I should add that this happens intermittently, so I guess I'm sometimes doing something differently within my shutdown/parking procedure that triggers the immediate switch in the ACARS mode, but I can't tell what it is that I'm doing.

Thanks.

[Hardy Heinlin]

Is there any add-on connected that might temporarily change the FMC origin/destination data?

[Will]

I was using PSX.NET to open the doors.

To those familiar with PSX.NET: is it plausible that it changed some things in the FMC?

[Will]

Just now, it happened without PSX.NET running.

I started with Basic 023 - ILS Capture, and changed the model to a passenger variant with NG FMC, and then landed the aircraft. ACARS changed from postflight to preflight almost immediately after the doors opened.

However, going through the same steps with the original situ (Basic 023, cargo variant, legacy FMC) doesn't do this; the ACARS POSTFLT index remains active as I expect it would.

Hardy, is this possibly happening because I'm starting with an old SITU (Basic 023) and changing the FMC to the NG version?

[Hardy Heinlin]

I can now reproduce the problem. I think it happens if a door is open before 30 seconds after engine shutdown have passed.

The FMC flight completion (full reset) status is set when 30 seconds have passed after engine shutdown.

The doors opening simulation just checks -- among other things -- whether all fuel switches are in cutoff. It won't wait 30 seconds.

So you can demo the problem like this:

Load Basic 027 - Parked and ready for engine shutdown.situ

Set APU GENs to ON, beacon light OFF, seatbelts OFF, all fuel switches to CUTOFF

Effect: The doors will start to open before the FMC sets the flight completion status. ACARS thinks the FMC is in preflight.


You can avoid the problem like this:

Load Basic 027 - Parked and ready for engine shutdown.situ

Set APU GENs to ON, seatbelts OFF, all fuel switches to CUTOFF, wait 30 seconds

Effect: The FMC sets the flight completion status.

Set beacon light OFF

Effect: The doors start to open after the FMC set the flight completion status. ACARS keeps the OOOI.


However, I just noticed another undesired effect: In any case, after engine shutdown, ACARS gets the FMC's origin/destination which the FMC (correctly) set to EHAM/EHAM after runway overflight (missed approach CLB in EHAM zone). ACARS should keep "TNCC/EHAM" and shouldn't change to "EHAM/EHAM".


Regards,

|-|ardy

[Will]

Thanks for looking at this, Hardy. Your troubleshooting skills are better than mine. I'm too quick to impute causation after observing correlation.

[Hardy Heinlin]

The modified OOOI reset logic is now available in PSX 10.151:

https://aerowinx.com/board/index.php?topic=4191.0


Regards,

|-|ardy