A320- different REC MAX FL between MCDU

[foelic]

Hello!

We were flying to our destination a few days ago when during cruise, I noticed there’s a discrepancy of up to 1,000 ft between REC MAX on the PROG page of both of our MCDU. AP1 was controlling the ac at that time

I checked my box and it shows a lower figure than the other. We were one hour in cruise. How come we are in a discrepancy? Same with our OPT FL.

ETA on the box, as well, was off between each other by up to 3-6 minutes. Clock was set to GPS.

I understand the FMGC computes the REC MAX by the ac gw and temp.

Checked fcom, fctm but with no luck.

Thanks to those who might be able to shed a light :)

[Escape Path]

Were the boxes working in normal mode or were they in independent mode or something like that? Maybe one of them was MEL'd or anything?

[safelife]

Maybe the temperature sensors of the plane didn't agree.
You can check by comparing TAS on both sides.
If they disagree, you can check AIDS alpha call-up 'TAT' so see both sides values.
If your plane is IAE equipped, you can compare to 'T2' (engine inlet temperature) to find out the correct side.

[FlightDetent]

+1 on the SAT sensors. FYI the SAT displayed on SD comes from ADR2 which feeds FMS2.

additionally, check GW in the FMS against each other. Again the value on SD permanent data line comes from FMS on the right side. (I've seen discrepancies up to 600 kg due to different FQI inputs).