A time constraint at any F-PLN waypoint can also be entered by the crew.
The crew has also the possibility to create a SECONDARY FLIGHT PLAN. This SEC F-PLN which has exactly the same structure as the ACTIVE F-PLN may be used for several functions:
-
Preparation of a second departure procedure before takeoff, when this one is defined late.
-
Preparation of the next flight while in flight.
-Training.
The SEC F-PLN may be created either by copying the active F-PLN or by
initialization as for the active F-PLN. It may then be displayed on the
MCDU (SEC F-PLN pages) and on the ND with a specific color. When created,
the SEC F-PLN may be activated under certain conditions. For more
details, Ref. section 22-71-00.
B. Lateral Functions The FMS lateral functions are made up of three main items. There are:
-Navigation (aircraft position)
-Radio navigation tuning
-Lateral guidance along the flight plan.
The navigation consists in determining the best estimate of the aircraft
position and to evaluating the accuracy of this estimate. The FMS uses
data from:
-ADIRSs for inertial speeds and positions
-DMEs for direct distance to various stations
-VORs for bearing to a station
-ILS for localizer update
-GPS sensors (if fitted).
These data are then mixed following various methods which are selected by
accuracy preference and signal availability. Normally, the three ADIRS
data are used and mixed together to provide the inertial position.
If data from one ADIRS are not available, then each FMS computes the
inertial position from only one ADIRS.
If no ADIRS data are available, then the FMS does not compute any
position: A/ POSITION INVALID message is provided.
The GPS data are used by the ADIRS to compute hybrid GPIRS positions; these GPIRS positions are transmitted to each FMGC which selects one of them.
The data from up to 5 DME stations may be used. These data are normally transmitted by the onside DME which is directly scanned by the FMS following an algorithm which researches the best DME station geometry as a function of the aircraft position. When 2 DME stations at least are correctly received, then the system computes a DME-DME position.
If only one DME station is received, the system uses the VOR bearing
associated to the DME (if any) to compute a VOR-DME position.
If no VOR is available, no radio position is computed.
The GPIRS or radio position, when present, is then mixed with the
inertial position through a complementary filter to provide the aircraft
position which is used for display and guidance.
When a LOC signal is available in approach, the FMS uses this LOC signal
to update the position.
The mode selection logic is described in section 22-72-00.
In addition to these computations, the FMS updates the aircraft position:
-At takeoff, on the runway threshold or intercept
-
In flight, on demand by the crew.
As additional navigation data, the system provides a class of accuracy
(HIGH or LOW) which depends on the algorithm used, on the nature of the
signals and the flight area (route, terminal, approach). Various warnings
are provided on the MCDU and ND when this class is modified.
Also the system computes the ground speed, the wind velocity/direction,
the distance to the active waypoint and the bearing and distance to any
pilot-selected waypoint or navaid.
The second function consists of the radio navigation and tuning. The
VORs, DMEs, ILSs and ADFs are normally tuned either automatically by the
system or manually by the crew on the RAD NAV page.
It has to be noted that, for manual tuning:
-
In normal case, both side receivers are tuned on either MCDU
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