Display of Predictions
Figure 008
2_ Submode
When CLIMB or DESCENT mode is active, the FM is responsible
for the choice of the active submode. It may be:
------------------------------------------------------------
| Elevator | SPD | V/S | VPATH | VPATH | FPA |
|------------|--------|--------|--------|--------|---------|
| Thrust | THR | SPD | SPD | THR | SPD |
------------------------------------------------------------
3 Targets
_ When CLIMB or DESCENT mode is active, the FM also provides the targets which correspond to the selected submode. In ALT ACQ or ALT mode, the FM provides a speed target, the altitude held is either the FCU altitude or the constraint altitude. The detailed logic for the altitude target determination is given in 22-12-00.
(b) Phase-by-phase presentation
1 Takeoff
_
a Takeoff parameters
_
-Takeoff speeds Before pushing the throttle control levers forwards, the pilot has to enter the takeoff speeds (V1, VR, V2) on the TAKEOFF page. V1, VR, once defined, are displayed on the speed scale of the PFD. V2 is also used as target speed for guidance during takeoff (TO/GA control law). The system also computes the minimum flap retraction (F), minimum slat retraction (S) and final takeoff (O) speeds versus takeoff gross weight. These speeds are displayed on the TAKEOFF page (Ref. Para. B).
-Flexible takeoff temperature / Derated takeoff (opt.) During preflight, the pilot may enter a flexible takeoff temperature or derated takeoff on the TAKEOFF page. If entered, the value is sent to the FADEC's.
-Takeoff altitudes Thrust reduction and acceleration altitudes are displayed on the TAKEOFF page. Their definition and revision rules are given in 22-71-00. (Ref. Fig. 009)
All these parameters are frozen after transition to takeoff phase.
Display of Takeoff Parameters
Figure 009
b Predictions
_ Takeoff predictions are based on the assumption that the aircraft will climb using takeoff thrust (either MAX TAKEOFF, or FLEX TAKEOFF, or DERATED TAKEOFF (opt.) maintaining a CAS of V2 plus 10 kts until reaching the thrust reduction altitude. At the thrust reduction altitude, the thrust is decreased to the MAX CLB value and V2 plus 10 kts is maintained until the aircraft reaches the ACCELERATION ALTITUDE which is the assumed end of the takeoff phase. (Ref. Fig. 010)
c Guidance
_
-guidance mode is TO-GA/SRS
-
at thrust reduction altitude the pilot is requested via the FMA to the throttle control levers in CLB position
-
at acceleration altitude, engagement of CLB is requested by the FM part to the FG part. (Ref. Fig. 011)
2 Climb
_
a Predictions
_ Predictions are based on an optimum climb strategy taking all climb constraints into account. The optimum climb is performed by holding the Max climb or Derated climb (optional) thrust and ECON speed (i.e. optimum speed limited by all applicable climb speed constraints including speed limit). But if this climb is above an AT or AT OR BELOW constraint, a level segment is inserted at the constraint altitude until the constraint point. No specific strategy applies to satisfy AT OR ABOVE constraints. In case of conflict between constraints, the following rules apply:
-the first climb constraint encountered downpath has the highest priority
-a descent segment is not allowed to satisfy an altitude constraint
-when a lower AT or AT OR BELOW climb constraint is downpath from a higher AT or AT OR ABOVE climb constraint, the lower downpath AT or AT OR BELOW constraint is ignored.
(Ref. Fig. 012)
F-PLN Predictions
Figure 010
Takeoff
Figure 011
CLIMB Profile
Figure 012
b Guidance
_
-mode requested by the FM part. The guidance mode normally requested by the FM part is CLIMB unless an altitude constraint requests a level segment (as described in predictions)
-
if the CLB mode is active, the requested submode and its
associated targets are as described in predictions -----------------------------------------------------| ELEVATOR | SPEED | | target | ECON climb guidance speed | |-------------------|-------------------------------| | Thrust | THR | | target | Max Climb Thrust | -----------------------------------------------------
-
if ALT ACQ or ALT mode is active, the speed target is the ECON climb guidance speed. (Ref. Fig. 013, 014, 015, 016)
