Speed Preselection for Climb Phase
Figure 029
Manual Speed Selection - Effect on Predictions
Figure 030
Descent Guidance - Aircraft on Profile (Nominal Case)
Figure 031
Descent Guidance - Aircraft above Profile
Figure 032
Display of Message SET MANAGED SPEED in absence of Manual Speed Preselection Figure 033
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-When the aircraft enters an HM leg, if the FCU selected speed is greater than the holding speed precomputed by the system, the message SET HOLD SPEED is displayed on the PFD and the MCDU.
(4)
Managed lateral control and selected vertical control Selected vertical control means that either OPEN, V/S, or FPA mode is engaged.
(a)
Effect on predictions In all these cases, predictions assume the immediate deselection of the mode and reversion to managed vertical control. That means that the rules described above apply.
(b)
Effect on guidance
-Mode, submode and at least one of the targets are determined in the FG part versus FCU selections. OPEN, V/S, FPA: Speed target is determined by the system if managed speed control is active: it is then equal to the ECON speed or holding speed. (Ref. Fig. 034)
(5)
Selected lateral control
(a)
Effect on predictions Predictions always assume an immediate return to the lateral flight plan with a 45. intercept law assumptions as described for managed lateral control.
(b)
Effect on guidance
-mode, submode and at least one of the targets are determined in the FG part versus FCU selections. In all modes, if managed speed control is active, the target speed is the optimum speed limited by speed limit when applicable (speed constraints are not considered since they are related to the lateral path).
-at 180 NM to the destination airport, the FM computes the required distance to land (DIST TO LAND) and the direct distance to destination (DIST TO DEST) for pilot information; they are displayed on the PROG page (if GPS option is not activated).
Required distance to land:
It is the distance required to pass from the A/C present energy
state to the landing energy state (with respect to limit and
final deceleration). It is represented by the "energy circle"
symbol displayed on the ND.
V/S in Descent (Aircraft above Profile)
Figure 034
Distance to destination:
It is equal to the distance from the A/C present position to the
LOC Capture Point (LCP) + distance from the LCP to the runway
threshold. In case of non-LS approach, the LCP is replaced with
the runway axis capture point.
(Ref. Fig. 035, 036)
D. Other Computations
(1) GW, FOB and CG revision rules The Gross Weight (GW), the Fuel On Board (FOB) and the Center of Gravity (CG) are displayed on the FUEL PRED page. (Ref. Fig. 037) These parameters correspond to current values. The following references are used: ZFW = Zero Fuel Weight ZFWCG = Center of Gravity of ZFW FOB = Fuel On Board CG = Center of Gravity of GW GW = Gross Weight BLOCK = Block fuel (Preselected fuel quantity).
(a)
A/C on ground before engine start The current FOB, GW and CG are not defined. The Takeoff Weight (TOW) is derived from pilot entries:
-ZFW entry (on the INIT B page)
-BLOCK entry or computation.
ZFWCG and ZFW data are entered by the pilot on INIT B page. These
data are used by the FM to compute the predictions and the
guidance speeds.
(b)
A/C after engine start
(Ref. Fig. 037)
-
The CG is submitted to any FOB or GW variation. The pilot may update this parameter by a new entry.
-
The FOB is computed versus information received from selected sensors : Fuel Quantity, fuel flow or both. The pilot may select any of these combinations (the default is both) as long as each involved sensor is valid. FOB entry deselects automatically fuel quantity sensor (sensor valid). If a sensor is invalid, it is deselected. The GW is submitted to FOB variations, including pilot modifications of FOB (ZFW remains unchanged). If the pilot modifies the GW, the ZFW is recomputed to take this into account. In flight, the GW is continuously crosschecked with A/C gross weight value computed in the FAC when available.
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