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_ 5
_Elaboration of orders (Ref. Fig. 022)
Operational logic The V/S FPA modes are activated if one of the conditions below is met:
-pull action on the V/S FPA selector knob on the ground, with the engine shut down or, in flight 5, seconds after lift-off
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engagement of one AP or FD in flight with no AP/FD previously engaged
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engagement of one AP in flight with no longitudinal mode active
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loss of GS capture or GS track mode due to the loss of LAND mode independent of the selection of a longitudinal mode (Ref. landing mode)
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loss of the FINAL DES mode independent of the selection of a longitudinal mode (action on the APPR pushbutton switch or loss of the active NAV mode) (Ref. R. NAV approach mode)
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loss of the NAV, LOC CPT and LOC TRACK modes or of the longitudinal flight plan in the DES or IM DES modes (Ref. level-change automatic-control modes)
-activation, by the FM part, of a flight phase incompatible with the active mode of the level-change automatic control (activation of the climb, takeoff or go around phase with DES or IM DES mode active).
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with the ALT ACQ mode active : . loss of FCU level capture conditions after selection of a new FCU target, or . activation of capture conditions of a lost altitude constraint
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with the DES, IM DES, EXP DES or OPEN DES mode active : the FCU level is set above the aircraft level (the target is the current aircraft vertical speed or flight path angle at the engagement of the V/S FPA mode)
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with the CLB, IM CLB, EXP CLB or open CLB mode active : the FCU level is set below the aircraft level (the target is the current aircraft vertical speed or flight path angle at the engagement of the V/S FPA mode)
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in descent modes (DES, IM DES, EXP DES, OPEN DES, F.DES) the aircraft speed becomes lower than VLS-2 kts (or VLS-17 kts if speedbrakes are extended) (speed protections exist with FD only engaged and A/THR active, when FD bars command is not carried out)
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in climb modes (CLB, IM CLB, EXP CLB, OPEN CLB) the aircraft speed becomes higher than VMAX+4 kts (speed protections exist with FD only engaged and A/THR active, when FD bars command is not carried out).
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V/S Mode Engagement Using (Turn and Pull) V/S FPA Selector Knob
Figure 020
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Altitude Hold Through V/S FPA Mode
Figure 021
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V/S FPA Control Laws
Figure 022
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(b) Level change OPEN CLB/OPEN DES mode
1 Characteristics
_ This mode enables to make level changes and minimize pilot actions. The engagement of this mode activates:
-holding of the speed or target Mach on the AP/FD
-command of a fixed thrust by the A/THR
. either limit thrust in climb
. or reduced thrust in descent.
2 Operational use
_ The level change mode is engaged through pull action on the altitude selector knob on the FCU whatever the longitudinal mode active, except landing mode. If the level selected in the ALT window of the FCU is higher than the aircraft level, the OPEN CLB mode is engaged and ensures the climb. (Ref. Fig. 023) If the selected level is lower than the aircraft level, the OPEN DES mode is engaged and ensures the descent. (Ref. Fig. 024) The attempt of engagement of the OPEN CLB and OPEN DES modes will not be taken into account if the mode active is ALT HOLD and if the selected altitude has not been modified. The OPEN CLB (OPEN DES) mode is lost and V/S FPA mode engaged when FCU level is set below (above) aircraft level. (Ref. Fig. 024) The OPEN CLB or OPEN DES mode is engaged automatically to ensure speed protection of the V/S FPA modes. When the V/S or FPA selected values are such that the aircraft performance no longer permits to maintain speed and if the stipulated minimum or maximum speeds are reached, engagement of OPEN CLB/OPEN DES mode permits to return to speed control on the AP/FD.
(Ref. Fig. 025) For level changes smaller than 1200 ft in OPEN CLB mode with A/THR active, the guidance is provided by the AP/FD in vertical speed mode ( + 1000 ft/mn reference), with the A/THR controlling the speed. This type of guidance avoids large thrust variations which are obtained through the successive activation of ALT-OPEN-ALT ACQ modes.
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