-character size
-use of various symbols
-color use.
These rules, when applicable are common with the EIS color rules.
Besides the data displayed by the system through the whole set of
pages, the FMGC may also display various messages in the scratchpad.
They may be used for:
-direct answer to a pilot entry (e.g NOT ALLOWED)
-recommendation to the crew (e.g TUNE TOU/117.9)
-acknowledgement of a specific event (e.g FMS1/FMS2 SPD TGT DIFF)
-warning of a degradation in functioning (e.g. NAV ACCUR DOWN GRAD).
Display rules vary as function of their importance. The most
important messages (linked to navigation or guidance) are also
displayed on ND or PFD.
(2) ND use The second basic instrument used for FMS operations is the Navigation Display (ND). As a recall, the ND works in 6 different modes selected on the FCU. For three of them (ARC, PLAN, ROSE-NAV) the ND displays the flight plan elaborated in the FMS at a scale defined by the range selected on the FCU. There is absolute correspondence between the flight plan displayed on the MCDU and the one displayed on the ND. When the MCDU displays the secondary F.PLN, the ND does so.
In addition to the active lateral flight plan, the ND displays various information concerning the navigation and the lateral/vertical guidance:
-Radio nav station tuned by the FMS for display or position calculation. They are located on the ND in accordance with the aircraft position and the flight plan.
-Wind magnitude/direction
-Self-elaborated message in case of disagreement between the radio nav frequency as selected by the FMS and the frequency actually tuned by the receivers.
-All the navigation data base waypoints, VOR stations, NDB or airport in the displayed area following the selection of the various options on the FCU.
-Cross track error and transition turns of the flight plan.
-Some important messages elaborated in the FMS.
-Pseudo waypoints computed by the vertical functions for vertical guidance aid.
(3)
PFD use Finally, a third instrument is used to display FMS information. The PFD as main guidance instrument displays the data computed or inserted in the MCDU such as ECON speed targets and target altitudes in automatic guidance modes, V1 and V2, DH, MDA or MDH (MDH if QFE option is activated) in approach.
(4)
FMS work The installation of the whole system is dual, following the architecture described in figure (Ref. Fig. 001) The FMS works then normally in DUAL mode based on the master/slave principle: the master FMS is the one associated with the autopilot engaged. If no autopilot is engaged, the side 1 is master. Based on this principle, all the data entered by a pilot on any MCDU are transmitted to both FMGCs through the intersystem bus. The computations in each side are made independently of the other side. However, the results are either synchronized (e.g. lateral F-PLN sequencing events, active flight phase) by the master side or compared (e.g. aircraft position). In the latter case, a miscomparison will lead to a message or even to the disengagement of the dual mode. The comparisons which may lead to disengage the DUAL
mode are the following:
data base incompatibility |
operational program | during power up
aircraft/engine model selection |
pin program mismatch. |
In this case, both systems work in independent mode. This means that the entry of data on one MCDU applies only on the same FMS side. The MCDU, ND and PFD displays are linked to the own side FMS. A long-term power up is required to intend to revert in dual mode. Each FMGC will tune its own side radio nav receiver. The crew has to tune the left side radio nav on the left MCDU, the right side radio nav on the right MCDU. This applies also to ILS selection.
A particular case of operation is when one FMS has failed. The alive FMS then reverts to SINGLE mode. The operations on the MCDUs are exactly similar to the DUAL mode except that the response time may be longer.
If an FM fails, the onside MCDU automatically synchronizes with the offside FM and the message OPP FMGC IN PROCESS is displayed on this MCDU. Onside ND and PFD also automatically synchronize with the opposite FM. The onside ND RNG selector should be set to the same value as the opposite ND, otherwise the SET OFFSIDE RNG/MODE message is displayed on onside ND.
FLIGHT MANAGEMENT SYSTEM (FMS) - SERVICING
__________________________________________
R **ON A/C 001-049, 051-061, 101-105,
TASK 22-70-00-610-006 Download the FM Data
1. Reason for the Job
__________________
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：A320飞机维护手册 AMM AUTO FLIGHT 自动飞行2(68)
