The story I'm getting is that the flight plan filed by CFD in MNL routed the flight back to MNL via MBT and AL due to volcanic activity near LP.
However, the ATC clearance issued was for the normal route via LP, NGA, and AL. Revised routing via the flight plan route was not requested.
The FCOM requires the MCDU flight plan and the ATC clearance to agree with each other if NAV mode is to be used.
It is apparent that someone set up the MCDU according to the filed flight plan instead of the issued clearance then used NAV mode.
So the flight deviated from FCOM procedures as well as the ATC clearance.
