5
_
6
_
7
_
This limit does not apply to a specific lateral path but
rather to a specific altitude. There is a system default speed
limit which is 250ft/10000ft.
There may be only two speed limits : one in CLB and one in
DES.
Cruise altitude
This is the altitude of the aircraft at the top of climb.
The cruise altitude is defined during active flight plan
initialization.
It is displayed and modifiable on INIT A page or Progress
Page.
(Ref. Fig. 015, 016)
If two cruise altitudes are defined, the first one is used as
the CRZ altitude and the second one as the step altitude (the
step is then automatically inserted in the flight plan).
Step climb-step descent
A step climb (step descent) in the flight plan occurs when the
vertical profile changes from one cruise altitude to a higher
(lower) cruise altitude.
A step may be automatically derived from data base if two
cruise altitudes are defined for the selected stored route.
The pilot may define a step on step prediction page which is
accessed through vertical revision page.
If below the current cruise altitude, a step descent will be
predicted and if above the present current cruise altitude, a
step climb will be predicted. There is only one step in the
flight plan at any time. If a second step is inserted, the
first one will be deleted.
Transition altitude
This is the altitude at which the altimeter barometric setting
is changed from the local value to standard (1013.2 mb).
It is only defined during takeoff, climb and go around phases.
The pilot may view on performance pages the transition
altitude.
This altitude may be derived from data base in the airport
record. Once an airport is defined the altitude is displayed
if it is defined in airport record.
If not, there are brackets to allow pilot entry.
(Ref. Fig. 012)
-During takeoff, the transition altitude is equal to the transition altitude displayed on takeoff page if any. Otherwise it is undefined. At transition from Descent or Approach to climb,
Progress Page (On Descent)
Figure 015
INIT Page A
Figure 016
or Approach to go around, it is set equal to the Trans alt which was displayed on the approach page just before phase transition if there was, else it remains undefined. At transition from Take off, Go around, Cruise to climb, it remains what it was just before phase transition (it may be defined or undefined).
-Transition level It is the flight level at which the altimeter barometric setting is changed from the standard (1013.2 mb) to the local value for the airport. It is only defined for descent and approach.
During descent and approach if there is a transition altitude
and a QNH value entered by pilot displayed on the approach
Perf page, it is computed from that value as follows (if not,
it is undefined).
(Ref. Fig. 017)
TRANS level is equal to:
1/100 Max (Trans alt, trans alt + delta alt (QNH) As the transition altitude, the transition level may be derived from data base or from pilot entry.
8 COST INDEX
_ This economical criterium enables the speed optimization along the whole flight plan. It is defined as the ratio of time cost and fuel cost so that the value of 0 means "minimum fuel" optimization and 999 means "minimum time" optimization. Any value may be defined by each company for each route according to its performance policy. The value is defined during active flight plan initialization (field 5L on INIT A page). (Ref. Fig. 016) In flight, this value may be modified for climb, cruise and descent phases by the pilot through the appropriate performance page.
(3) Secondary F-PLN The pilot may define a secondary flight plan by having access to the SEC INDEX page after action on the SEC F-PLN mode key. The secondary F-PLN is defined as the primary flight plan with the same kinds of lateral and vertical elements. The pilot may perform lateral and vertical revisions but there is no temporary situation as for the primary F-PLN. In this secondary mode, the available pages are :
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本文鏈接地址：A320飛機維護手冊 AMM AUTO FLIGHT 自動飛行3(17)
