RNAV and constant climb/descent

[ECAM_Actions]

Hi,

I'm struggling to find any information regarding how an FMC/FMS/FMGC (I think that is most types covered :E ) handles continuous climbs/descents.

The only time I've seen this is on RNAV departures/arrivals, and I wondered whether this particular way of flying was specific to RNAV procedures, and whether the flight management system can be persuaded to fly this way with pilot-entered waypoints (for example)?

e.g. suppose the aircraft is approaching a waypoint with the constraint CROSSING AT 8000 ft, yet the aircraft has the performance to be at 8000 ft 5 nm before the waypoint. On an RNAV departure I have seen the aircraft fly a path that will ensure it passes the waypoint at 8000 ft, but at a shallower climb angle than it is otherwise capable of. Is this standard for any type of waypoint, or only RNAV procedures?

ECAM Actions.

[Upper Air]

It, the FMS, does not matter nor does it care whether or not you shallow climb to waypoint or climb and then level off due to a constraint.

If you shallow climb to a constraint as part of an RNAV procedure and you have experienced climbing to waypoints in a hard climb then levelling off at the waypoint, to continue climb after the waypoint, that is probably because your waypoints were close together like in a SID.

[Upper Air]

As you know you cannot/should not build waypoint into a datbased STAR or SIS or DP If, you have a string of wpt as a . . . transition say then the aircraft will descend to the next constraint say: 4,000/Nicky - you will have a lower altitude set say 3,000 alt, so the aircraft will level out at 4,000, fly past the waypoint, then continue descent to the next constraint, if any, and so on all the way down to your selected altitude.

Same for the climb, the aircraft will be at your waypoint at the desired altitude when you have alt constraint on it. You can modify this by entering AT altitude, NOT ABOVE altitude or NOT BELOW altitude, which you would plug into your FMS, prior to departure - or it would already be in there as part of the Descent/Climb/STAR/SID/WHATEVER.

If you are receiving ATC Radar giving you alts (up or down - Dep or App) then you would naturally, clear the constraints, or disc AP or just clean up the box and leave in the approach.