OPEN CLB Mode - Mode Selection When ALT SEL > Current Altitude
 Figure 023

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 IN OPEN CLB Mode - V/S Mode Selection When ALT SEL < Current Altitude

 Figure 024
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 OPEN CLB Mode - V/S Demand Above Performance Capability
 Figure 025

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Speed/Mach switching
 In climb mode and manual speed control, the Speed-to-Mach
 switching is automatic and commanded by the FM part, when the
 aircraft reaches the switching altitude computed by the FM
 part, depending on the selected speed.
 The corresponding Mach value which corresponds to the
 switching altitude and displayed on the CLB page of the MCDU
 is synchronized in the SPD MACH window of the FCU display.
 (Ref. Fig. 023)
 Similarly, in descent mode when the aircraft reaches the
 switching altitude, the FM part commands the change to speed
 control, and the speed which corresponds to the Mach number
 selected and to the switching altitude is synchronized in the
 FCU window.
 This automatic switching can be overridden by the pilot via
 the related pushbutton switch on the FCU and on switching, the
 window is synchronized with the aircraft Mach number or speed.
 (Ref. Fig. 026)

Elaboration of orders
 (Ref. Fig. 027)
 The principle consists in splitting the aircraft total energy
 into two parts:

 -70% for acceleration or deceleration
 -30% for climb or descent. The total flight path gamma T is the checking parameter. Upon engagement of the OPEN CLB mode and during establishment of the limit thrust to IDLE, the AP/FD guidance is ensured by the vertical speed law (Reference equal to + 8000 ft/mn). This type of guidance improves the load factor and speed hold performance during the thrust transient. In the cases below:
 -A/THR disengaged or not active,

 -deceleration commanded in climb,
 The SPD/Mach law ensures AP/FD guidance as soon as the mode is
 engaged.

Operational logic The OPEN CLB and OPEN DES modes can only be engaged if the conditions below are met:
 -
the ALT ACQ mode can be armed

 -
the aircraft is on the ground (engines stopped) or in flight for more than 5 seconds

 -
the LAND TRACK mode is not active

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 - the FCU level is above the aircraft level (engagement of
 OPEN CLB mode) or below the aircraft level (engagement of
 OPEN DES mode).
 The OPEN CLB mode is activated if one of the conditions below
 is met:
 - pull action on the altitude selector knob
 - with CLB or IM CLB mode active :
 . switching to Descent, or
 . Approach phase, or
 . loss of NAV mode or loss of flight profile validity.
 - Selection of the manual speed control, when in EXP, takeoff
 or go around mode (Ref. EXP mode, if fitted)
 - the acceleration altitude reached is an armed CLB mode on
 condition that the NAV mode is not active or the flight
 profile is not valid (Ref. CLB mode).
 The OPEN DES mode is activated if one of the conditions below
 is met:
 - pull action on the altitude selector knob
 - selection of manual speed control with the EXP mode engaged
 (Ref. EXP mode).
 Speed protection of the V/S FPA modes is engaged if the
 following conditions are met :
 - V/S Sel or FPA Sel >0 and speed lower than or equal to VLS +
 5kts.
 - or V/S Sel or FPA Sel <0 and speed greater than or equal to
 VMAX - 5kts in clean configuration or VMAX +4kts in flap and
 slat extended configuration.
 NOTE : The speed protection is active 5 seconds after____
 light-off but is inactive if a speed protection from
 OPEN to V/S FPA mode occurred less than 30 seconds
 before. 
R  (c) Expedite (EXP) mode 
R  1 Characteristics_ 
R  The EXP mode permits to perform level changes with the maximum 
R  flight path angle in climb as well as in descent. 
　
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