Da odgovorim sam na svoje vprašanje.
Pr natančnejšem branju Automatic Flight Management Systems sem našel tole:
Citiram:
Once the approach is fully captured, APP mode can be disengaged by:
• Pushing the TO/GA switch (click on upper left screw on MCP in the PMDG airplane. In the actual airplane the TOGA switch is located on the throttle under your thumb but that could not be modeled here.)
• Disengage the autopilots and turn off both Flight Director Switches.
• Tune the VHF Navigation receivers to a new frequency.
It's not a bug, it's a feature.