-DESCENT  : from the top of descent down to the DECEL point, which is
 the start of decelerated approach. It can include a descent
 speed limit and several speed, altitude and flight path
 angle constraints

 -APPROACH  : from the DECEL point down to the destination (runway threshold, airport or missed approach point). It can include several speed, altitude and flight path angle constraints
 -GO AROUND : missed approach procedure
 -DONE  : aircraft on ground, primary flight plan data are cleared. Except for the first and last ones, each of these flight phases is displayed in the title of the PERF page which is accessed when the PERF key is pushed. When present flight phase is PREFLIGHT or DONE, the PERF key action gives access to the TAKEOFF PERF page. The same display of the flight phase is repeated in the title of the PROG page. See following figure for a typical vertical trajectory where all phases are involved only once.
 (2) Flight Phase Transitions
 The following flight phase transitions are possible:

 -------------------------------------------------------------------------------| FROM |PREFLIGHT|TAKEOFF|CLIMB|CRUISE|DESCENT|APPROACH|GO AROUND|DONE| | TO | | | | | | | | | -------------------------------------------------------------------------------|(1) PREFLIGHT | | | | | | | | X | |--------------|---------|-------|-----|------|-------|--------|---------|----| |(2) TAKEOFF | X | | | | | | | X | |--------------|---------|-------|-----|------|-------|--------|---------|----| |(3) CLIMB | | X | | X | X | X | X | | |--------------|---------|-------|-----|------|-------|--------|---------|----| |(4) CRUISE | | | X | | X | X | | | |--------------|---------|-------|-----|------|-------|--------|---------|----| |(5) DESCENT | | |  X  | X | | | | | |--------------|---------|-------|-----|------|-------|--------|---------|----| |(6) APPROACH | | | X | X | X | | | | |--------------|---------|-------|-----|------|-------|--------|---------|----| |(7) GO AROUND | | | X | X | X | X | | |  -------------------------------------------------------------------------------| FROM |PREFLIGHT|TAKEOFF|CLIMB|CRUISE|DESCENT|APPROACH|GO AROUND|DONE| | TO | | | | | | | | | -------------------------------------------------------------------------------|--------------|---------|-------|-----|------|-------|--------|---------|----| |(8) DONE | | X | X | X | X | X | X | | -------------------------------------------------------------------------------

Conditions for flight phase transition to:
 (a)
 PREFLIGHT phase This flight phase becomes active when INIT or PERF key is pushed in DONE phase.

 (b)
 TAKEOFF phase It becomes active when ground speed or engine rate reaches takeoff rate, from DONE or PREFLIGHT phase.

 (c)
 CLIMB phase CLIMB becomes active from TAKEOFF or GO AROUND flight phases when the aircraft altitude increases above the acceleration altitude or at pilot engagement of a vertical autopilot mode other than SRS. CLIMB is also recovered from DESCENT, APPROACH or CRZ phases each time the aircraft altitude becomes lower than the (possibly new) cruise altitude (except if there is a preplanned step).

 (d)
 CRUISE phase It becomes active from CLIMB, DESCENT or APPROACH phase each time the aircraft altitude becomes greater than or equal to the (possibly new) cruise altitude.

 (e)
 DESCENT phase It becomes active from CRUISE or CLIMB phases when the aircraft (not too far from the destination) begins a descent to a clearance altitude below the cruise altitude without preplanned step.

 (f)
 APPROACH phase

 -
It becomes active from DESCENT when the aircraft has passed the DECEL point, the aircraft altitude is not too high and NAV mode is engaged.

 -
It can also be activated manually from CLIMB, CRUISE, DESCENT or GO AROUND phase when the CONFIRM APPR PHASE prompt is selected on the PERF page. (Ref. Fig. 003)

 Manual Activation of APPROACH Flight Phase
 Figure 003

 (g)
 GO AROUND phase It becomes active from the APPROACH phase when the PITCH GO AROUND mode is engaged.

 (h)
 DONE phase It becomes active from any other phase than PREFLIGHT when engines are stopped on ground. In addition, it may become active from APPROACH flight phase as soon as sufficient time has elapsed with aircraft on ground.

 B. Speed Generation
 (1) Optimization Several reference and optimum speeds are used for MCDU display, for performance computation and for guidance when SPEED AUTO CONTROL is active. They are takeoff, approach and go around speeds, optimum climb, cruise and descent speeds, and situational speeds (as expedite and holding pattern speeds).
　
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