This is VNAV Management Issue from A320 to A380, mate.

I forgot to tell you this, @iniKyle . But A380 have issue if there's 2 overlapping SPEED CONSTRAIN.

Like the VNAV capability unable to prioritize which one to be use. It is chaos whenever you are descending to any airports, having STAR wtih turn or straight-in. The Energy Management is worst especially below 10,000 feet during descend.

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Usually there's 3 SPEED CONSTRAINT on VNAV:

1. STANDARD Speed Limit Constraint, noticable by 250kt/10,000feet,

2. PUBLISHED ARRIVAL Speed Constrain, usually there's speed limit for Departure and Arrival Published Speed Limit at specific waypoint,

3. SELECTED Speed Constrain, this is inserted by pilot for flight management planning,

I notice that A380 ONLY FOLLOWING Speed Limit number 1, whenever there's number 2 and/or number 3, the VNAV failed to do as programmed.

And if there's speed constrain on specific W/P, the VNAV is ALWAYS targeting the speed constrain by the NEXT W/P not on the target W/P.

Like the picture above, for context:

• DB515 having speed 210 knots, but somehow the VNAV targeting to reach 210 knot AT DB514 or DB513. and

• DB508 having speed 185 knot, VNAV will target specified speed either on DB507 or DB506, or even worst sometimes at DB505, WITHOUT DECEL P/WP between GIRGO to RIDEV.

This is ALWAYS happening whenever you are either having turn (most cases) and/or during straight-in STAR. Like, VNAV prioritize ONLY the path without calculating the pre-selected speed requirement (somehow, only the speed 250/10000 is prioritized more than the path or any selected speed).

Based on the infrastructure of FMCGS, the path calculated with Continuous Descend Operation (CDO), descend with the lowest energy available (Idle Descend) with calculating 4 factors:

1. ANY CONSTRAIN (Speed and/or Altitude Constrain) inserted whether from arrival procedures speed limit or selected speed limit target, (yes, it calculates BOTH constrain)

2. Idle Power Descend possible (the lowest energy available, WITHOUT having to extend speedbrake),

3. Pre-selected Wind Condition (or zero-wind if the wind from simbrief NOT inserted), and

4. CDO finished at IAF.

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I know this is loooonnngggg structure modification. But please, make a correction about this. Somehow, PMDG and TFDi having it better about this (I don't mean to compare, but this is only happens on IniBuilds except for A300/A310).

And the most funniest things, A350 Prioritizing Speed Constraint but A380 Prioritizing Altitude Constrain (until you hit speed limit 250/FL100) 😆

I hope this can be corrected for the future upcoming development.

Cheers!