Denti,
Good question, we don’t have the IAN option so I have not looked into this and I am therefore not qualified to answer. However as the 10.8 anomaly affects approaches constructed from the FMC, and IAN uses an FMC derived glidepath rather than an ILS glideslope, I would prohibit IAN approaches until receiving conformation from Boeing that it was safe to continue with U10.8. I doubt it will be.
Here is some of the info I have. I cant reproduce it all due to copyright:
“Boeing has received reports from several operators regarding anomalies associated with the Update 10.8 (U10.8) FMC VNAV operation. One operator reported 3 events where the FMC displayed the message "STEEP DESCENT AFTER XXXX" on a specific VNAV approach. The XXXX was the FAF (Final Approach Fix) waypoint in the descent approach segment. Upon sequencing the FAF, the autoflight system commanded the airplane to descend below the expected path on approach.
…has determined that an error in the FMC U10.8 software result in the VNAV path being built to the wrong waypoint, specifically to a waypoint with an AT constraint upstream of the waypoint where the steep descent takes place.
… An error in the prediction logic may calculate an incorrect path between the AT waypoints that is lower than the published navigation database (NDB) path. Under these conditions, the published NDB path is not honored.”
The U11.0 features I listed are not confirmed yet, but are hotly tipped. The latest I am hearing is that RTE 2 may not be included in U11.0 but I am not sure.
I did not say that VNAV armed before take-off was a new feature, it has been available since U10.7. However crew were instructed not to use it in FCOM OMB TBC-70, “Arming VNAV on the Ground (FMC Update U10.7)”, dated 11 June 2007. U10.8 fixes this and removes the restriction.
S&L