-lateral control,
-longitudinal control as far as level changes are concerned.
(a)
Speed control The associated light comes on when the managed speed control is active.
(b)
Lateral control The associated light is on when:
-
the lateral guidance is managed, i.e. when the modes below are active: . NAV . LOC CPT . LOC TRACK
-
the managed lateral guidance is armed, i.e. the modes below are armed: . NAV . LOC.
(c)
Longitudinal control The associated light is on when:
-
the level change is automatic i.e. when the modes below are active: . CLB . DES . IM CLB . IM DES
-
the automatic level change is armed when the modes below are armed: . CLIMB . DESCENT.
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COMMON MODES - DESCRIPTION AND OPERATION
________________________________________
1. General
_______
The AP/FD modes common to the longitudinal and lateral axes are:
-TAKEOFF (TO)
-ILS approach (LAND) or FMS approach (AREA.NAV)
-GO AROUND (GA).
These modes are engaged simultaneously on both axes.
However, it is possible to leave TO and GA modes one axis after the other.
The selection of the LAND or GA mode authorizes the engagement of both APs.
The engagement of the lateral and the longitudinal cruise modes is
impossible as long as the AP or the FD is engaged in LAND TRACK or GO AROUND
mode below 100 ft RA.
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2. System Description
__________________
A. TAKEOFF Mode (TO)
(1)
Principle This mode provides lateral guidance function, at takeoff, on the runway centerline by means of the LOC beam and by following an optimum longitudinal flight path after rotation. This mode is available:
-
for the FD during takeoff run and in flight
-
for the AP 5 seconds after lift-off.
The mode is engaged when the pilot selects the takeoff thrust by
positioning the throttle control levers beyond the MCT/FLX TO gate.
Engagement of the mode is shown by the green SRS and RWY indications
in the FMA columns corresponding to the longitudinal and lateral
modes.
(2)
Pitch Axis
(a)
Operational use (Ref. Fig. 001) The pitch guidance law enables holding of V2 + 10 kts in dual-engine configuration. Prior to mode engagement, the pilot must select speed V2 on the TAKEOFF page of the MCDU. With V2 selected, the managed speed control is activated and the TO longitudinal mode (PITCH TAKEOFF) can be engaged. Without V2 selection on the MCDU, the mode is not engaged on this axis. Engagement of the PITCH TO mode results in managed thrust control (A/THR (aotothrust)). The A/THR is not active as long as the throttle control levers are positioned beyond the CLB gate.
(b)
Engage logic (Ref. Fig. 002) The engagement conditions of the PITCH TAKEOFF mode are shown in figure. The engagement condition on the position of the throttle control levers takes into account the following facts:
-
if a FLEX limit has been selected, the mode is engaged as soon as the MCT/FLX TO gate is reached
-
if no FLEX limit has been selected, the mode is engaged as soon as at least one throttle control lever is positioned beyond the MCT/FLX TO gate.
It is possible to disengage the PITCH TO mode only by engaging another longitudinal mode. The mode will be lost further to selection of selected speed control for engagement of the OPEN CLB mode (Ref. 22-12-00).
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Takeoff with NAV Armed
Figure 001
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1
PITCH TAKEOFF Mode - Logic
Figure 002
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1 1 Feb 01/98
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1CES 1
(c) Guidance law (Ref. Fig. 003) The SRS guidance law called when the PITCH TO mode is engaged, is shown in figure. This law enables to hold V2 + 10 kts in dual-engine configuration (V2 is memorized in the guidance part at engagement of the PITCH TO mode). In single-engine operation, the law enables to hold:
-the aircraft speed if it is greater than V2 when the engine failure occurs.
-V2 if aircraft speed is lower than V2 when the engine failure
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