-CLB mode can be armed or engaged only in LATERAL AUTO CONTROL, below FCU selected altitude. In CLIMB or CRUISE phase when CLB mode is engaged, speed is held with the elevators and maximum available thrust is targeted. In CLIMB phase when a level off is required for an altitude constraint, ALT ACQ mode is engaged automatically and CLB mode is armed for automatic re-engagement when the constraint is passed.
-DES mode can be armed or engaged only in LATERAL AUTO CONTROL, above FCU selected altitude.
In CRUISE phase, DES mode can be engaged manually to perform a step-descent or to initiate DESCENT phase. When DES mode is engaged for a step-descent, the elevators maintain -1000 ft/mn and speed is held with thrust. In DESCENT or APPROACH phase, when DES mode is engaged guidance depends on aircraft position relative to the vertical flight path and whether aircraft speed is correct. Elevators are used to control the aircraft to the path. Thrust can be applied to prevent underspeeding or to maintain speed. When the aircraft is above path or overspeeding, idle thrust and speed elevator control is used. If the aircraft is below path or inside a holding pattern, vertical speed or flight path angle elevator control is used and speed is held with thrust. To minimize throttle movement in SPEED AUTO CONTROL, aircraft speed is allowed to vary within a certain margin which is displayed on the PFD. In SPEED MANUAL CONTROL, there are no margins and selected speed is maintained. When a level off is required for an altitude constraint, ALT ACQ mode is engaged automatically and DES mode is armed for automatic re-engagement when the constraint is passed. Altitude constraints are ignored when flying an HM.
-FINAL mode can only be armed for a non-precision approach : VOR, NDB or RNAV. The system can engage FINAL mode only in LATERAL AUTO CONTROL, during APPROACH phase, when the aircraft is close enough to the lateral and vertical approach paths and beyond the DECEL point. When FINAL mode is engaged, elevators are used to control the aircraft to the path and speed is held with thrust. FCU selected altitude is ignored in FINAL mode.
(3)
Targets In SPEED AUTO CONTROL, the FM can provide speed targets for display and guidance.
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in EXP CLB mode: max (VMAN, VLS)
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in EXP DES mode: min (VMO-10, MMO-0.02, VMAX)
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In LATERAL AUTO CONTROL: aircraft speed will follow the predicted speed profile. Speed constraints, limits and holding pattern speeds are observed. The aircraft will anticipate on decelerations as required.
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In LATERAL MANUAL CONTROL: speed constraints, which are tied to the lateral path, are not taken into account. Only speed limits are observed below their specified altitude.
In CRUISE phase beyond the top of descent and during DESCENT and APPROACH phases, the vertical flight path altitude is displayed on the PFD altitude scale. When FINAL mode is armed or engaged, it is displayed relative to aircraft altitude on a specific precision scale.
In LATERAL AUTO CONTROL, the corresponding vertical deviation (flight path altitude minus aircraft altitude) is displayed on the MCDU. In LATERAL MANUAL CONTROL, the required distance to land (minimum distance to descend and decelerate to VAPP at destination) and the direct distance to destination (via the LOC capture or final approach point) are displayed instead.
(4)
Visual cues Specific symbols are displayed on the ND. DECEL point excepted, they are predicted according to the modes which are actually engaged, unlike MCDU F-PLN predictions.
-The magenta DECEL "(D)" symbol is displayed on the flight plan at the point where the aircraft is expected to begin decelerating to approach speed, and beyond which FINAL mode is allowed to engage. It is identical to the MCDU (DECEL) point.
-LEVEL OFF symbols are displayed where the aircraft will level off for an altitude constraint (in magenta colour and only in CLB, DES or FINAL mode) or to FCU selected altitude (in cyan).
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In LATERAL AUTO CONTROL, START OF CLIMB or TOP OF DESCENT symbols are displayed on the flight plan where the aircraft should (in white) or actually will (in cyan) resume climb or descent after a level-off.
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In LATERAL AUTO CONTROL, a path INTERCEPT symbol is displayed on the flight plan in DESCENT or APPROACH phase at the point where the aircraft should (in white) or actually will (in cyan) capture the vertical flight path.
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In LATERAL AUTO CONTROL, altitude constraints are highlighted with a "o" symbol. In V/S, FPA, EXP, or OPEN modes, it can be displayed in white only at the TO waypoint. Otherwise, it can be displayed at the next 2 down path constraints in amber or magenta, according to whether the constraint predicted missed or made.
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本文链接地址：A320飞机维护手册 AMM AUTO FLIGHT 自动飞行2(56)
