Copyright D.P. Browne 2011
The Auto thrust system is part of the FMGS and controls the engine thrust via the FADEC in order to archive the target values of Speed or Mach, or Thrust. The A/T is active when the A/THR is indicated in white on the FMA and the A/THR button is green on the FCU.
Auto Thrust
The engine’s thrust may always be controlled by the pilots by moving the thrust levers, when the A/T is disengaged or armed. There is an A/T disconnect button on each thrust lever. The position of the thrust levers determine wether the A/THR is active, armed or disconnected.
Thrust Levers
Arming
Engagement
A/THR disconnect
A/THR modes
IAS speed mode using either FCU speed or managed MCDU speed
Mach mode using either FCU Mach or managed MCDU Mach
N1/EPR thrust climb limit , or minimum thrust in descent
Retard mode in auto land
|
|
|
Thrust lever Disconnect |
Other |
|
Consequence |
Master Caution |
Illuminated for 3 seconds |
Illuminated |
|
ECAM |
Amber A/THR Off message for 9 seconds |
ENG THRUST LOCKED
| |
|
CLR push button on ECAM Control Panel |
extinguished |
illuminated | |
|
Action |
Master Warning Pressed |
Extinguishes Master Warning Light Erases ECAM message Stops Audio chime |
Extinguishes Master Warning Light Stops Audio chime |
|
CLR push button on ECAM Control Panel, pressed |
No effect |
Extinguishes the CLR button pb and erases the ECAM message | |
|
Trust Lever Disconnect Button pressed |
Extinguishes Master Warning Light Erases ECAM message Stops Audio chime |
Extinguishes Master Warning Light Stops Audio chime | |
|
ECAM Status Message |
|
NO |
YES |
The A/THR may be disengaged when :
The A/THR disconnect buttons on the thrust levers are pressed
The thrust levers are moved to the idle position
The A/THR switch on the FCU is pressed (when illuminated green)
The Auto thrust system monitors a fault condition
The thrust levers on Airbus aircraft are used as an mode input to the A/THR system, and determine the maximum thrust targets.
The A/THR is armed by the flight crew when
Pressing the FCU A/THR push button on the ground
Setting the thrust levers beyond the CL detent when the engines are running
The A/THR is engaged by the flight crew when
Setting the thrust levers between the MCT and idle detent when one engine is running
Setting the thrust levers between the CL and idle detent when the engines are running
The A/THR is engaged automatically when
Alpha Floor state exists
When the A/THR system is armed. A/THR is indicated in the FMA in blue.
When the A/THR system is active. A/THR is indicated in the FMA in white.
CAUTION : If the Thrust levers disconnect button are pressed and held for 15 seconds,
the A/THR is disconnected for the entire flight and can only be re-