Can anybody explain why LNAV and VNAV are disarmed above 80 knots when TOGA is pushed. As far as I know, the 744 does not have this feature.
For the 747..
on roll, with LNAV/VNAV armed, selecting TOGA, thrust moves to THR REF.
At 65kts, FMA reverts to HOLD and allows manual adjustment of thrust.
IF LNAV is armed, at 50', TOGA roll replaced with LNAV.
At 250' autopilot can be selected
If VNAV armed, at 400', TOGA is replaced with VNAV SPD
similar in the wording and intent.