4_ Altitude constraints are shown by a specific symbol at the
next constraint waypoint. They are displayed in magenta or
amber, if they are predicted to be satisfied or missed in the
present autopilot mode.
5_ Intercept point shows the point where the aircraft will
intercept the descent profile. It is in white in any manual
vertical mode, or in cyan in automatic vertical mode.
The fuel policy is defined by various parameters which are stored in AMI data base. Up to 8 different types of fuel policy can be stored in data base.
(d)
Altitude planning This function computes the distance and time required to reach a predetermined altitude. This calculation is made for the active speed mode (ECON or manual speed) and for the EXPEDITE mode. It is available only in takeoff, climb and descent phase.
(e)
Performance factor In order to adjust the aircraft/engine model versus the actual aircraft performance, it is possible to define 2 performance factors. These values can be defined by AMI data base and modified by the crew (protected entries).
(f)
Overview of alternate The system provides time and fuel predictions for up to 6 alternate destinations defined in Navigation data base in the airport file. A seventh airport may be selected by the crew and the NO ALTERNATE option is also evaluated. Airway distance is used in this computation.
(g)
Maximum altitudes A maximum recommended altitude is computed and displayed on the MCDU. It uses limitations from the engine max climb thrust, buffeting
(0.3 g margin) and max certified altitude. An absolute maximum altitude is computed and limits the CRZ FL entry. It is defined as the previous one except that a 0.2 g buffet margin is used.
(h)
Max holding time When the aircraft flies in a holding pattern, then the system computes the maximum time the aircraft can remain in the holding pattern. It uses for this computation, the fuel policy, the alternate selection and assumes 0 extra fuel.
(i)
Secondary flight plan In order to achieve the usage goals of the secondary flight plan as described in para. A., the system computes the exact same flight plan predictions as for the active flight plan, provided some conditions of consistency between both flight plans are respected. These computations include fuel planning.
D. Operational Use The interface between the crew and the FM is performed through the various displays in the cockpit and particularly the MCDU and the ND. This section deals with the general rules defining the use of these computers from an FMS standpoint. The general use with 2 FMGCs is also explained.
(1) MCDU use The MCDU is used to select data in the system (pilot entry) and to display most FMS information to the pilot. Although the MCDU is used for various systems (CFDS, ATSU, AIDS and optional SAT), it is coupled by priority to the FMGC. This means in particular that a direct access to an FMGC page can be obtained by selecting the corresponding mode key.
The MCDU keyboard is composed of an alpha-numeric part used for pilot entry. When the pilot presses one of these keys, the corresponding symbol is written on the 14th line of the CRT (the scratchpad line). When all data are entered in the scratchpad, the pilot must then press the line select key to insert the information in the scratchpad. It is possible to clear this information partially or entirely by means of the CLR key. Specific rules concerning format, possible entries or clearing functions, are defined.
The MCDU keyboard features several mode/page keys:
-The MCDU MENU mode key gives access to a menu page which allows selection of the coupling of the MCDU to any other system.
-10 page keys give access to the corresponding pages. Some pages are usually displayed as a function of the flight phase: . INIT and F.PLN pages before takeoff . F.PLN and PERF pages during takeoff . F.PLN and PROG pages during climb, cruise and descent . F.PLN and PERF pages during approach and go around. Pages may automatically vary in data and format as a function of the flight conditions. For example, the F.PLN page is modified each time the flight plan is sequenced. Some pages may also give access to other pages through a hierarchy.
-4 mode keys are used to modify the displayed page when all the information to be displayed does not fit in one page. These keys allow either vertical slewing or horizontal slewing.
In order to display the information, the FM is constrained to satisfy various rules. They are applied also to any other computer linked to the MCDU. These rules concern:
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