AUTHOTHRUST

[AIRBUS58]

FOR AIRBUS PILOTS.

WHEN BEFORE FLIGHT DO YOU ENGAGE A/TH ?
WHEN DOES IT BECOME ACTIVE ?
HOW IS IT MANAGED BEFORE LANDING?
WHEN AFTER FLIGHT DO YOU DISCONNECT IT ?

THANKS.

[Three-Twenty]

A/THR is throughout the flight:

technically, when we take off, the A/THR is 'armed' with the thrust levers in TOGA or FLX setting, when we bring the thr lvrs back to Climb power at about 1500' agl then the A/THR become 'engaged' and speed and thrust setting are controlled via the FCU/FMGS.

The position of the thr lvrs really just tells the system the MAXIMUM thrust that it is allowed to apply, if we bring the thr lvrs back w/o pressing the little red buttons on the side then A/THR is still engaged but is limited to whatever thrust setting the levers are at.

'course, you can always just disengge it and use the thr lvrs like normal (dare I say it..) 'throttles' (ugh!)

It is disengaged once the thr lvrs are brought back to idle on landing. putting the thr lvrs back to FLX or TOGA re-arms the A/THR.

Basically.

[Silky]

To try and answer all questions
FOR AIRBUS PILOTS.
WHEN BEFORE FLIGHT DO YOU ENGAGE A/TH ?
WHEN DOES IT BECOME ACTIVE ?
HOW IS IT MANAGED BEFORE LANDING?
WHEN AFTER FLIGHT DO YOU DISCONNECT IT ?


Autothrust is armed on the ground when flex or toga is selected for take off ( as three twenty stated) We know this by Autothrust BLUE in the right hand corner of the FMA.
As previously stated it becomes active at thrust reduction altitude, we again see a change on the FMA as it has changed to white (active). The active range on two engs is from idle to clmb, in single eng op's, it is active between idle and MCT. If at any stage you advance the TL out of the detent for the twin or single eng range athr will go BLUE again as it is again armed.

As for disconnection, there are two types... 231-232cpip. The standard procedure (airbus) is to retard the TL to the actual power setting and then disconnect the Athr. Previously if in clmb you disconnect the AThr you would get Thrust locked until you moved the TL and then the thrust would go to the actual position of the TL. The newer type (232cpip) is such that as soon as you disconnect ATHR it will go to the actual position of the TL rather than waiting for you to remove it from the clmb gate.
Athr is disconnected in 3 ways, selection of idle, the instinctive disconnect buttons on the TL and the Athr button on the FCU. On landing IDLE is selected for touch down therefore Athr is disconnected. Hope this helps
:) :)


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Gravity always wins....

[This message has been edited by Silky (edited 17 October 2000).]

[AIRBUS58]

Thanks for the fast responces to my questions ,THREE TWENTY and SILKY.

Just the information I was looking for .

Im I right in saying the A/TH is arm on on the ground when you select the A/TH switch on the FCU to arm the system.
The system is not active until you bring the thrust levers back to CLM at the thrust reduction altitude.

So putting the s/w to arm engages the system but it can be active or not active depending on the thrust levers position , and flight envelope protections.

To disconnect the system you can operate the levers disconnect button or the FCU switch
Have I got the right understanding now?

[jtr]

Umm, you've sort of got it.
You don't actually ARM the A/THR as such. The arming occurs by default when you put the levers in the FLX, or TOGA detent.

It is activated (again by default) when you place the levers in the CLB detent at thrust reduction alt.

To disarm it, you can do any of the following;
press the button on the levers.
set the levers to idle.
push the FCU button (non standard)
stick the levers anywhere foward of the CLB detent

(The above all applies to all engines case. Things change a little when eng-inop.)

Diconnecting it is a matter of personal preference, and also dictated by A/C type. In gusty winds, most I work with disconnect it, and fly manual thrust from 1000' down. The A330 A/THR (with RR engines) performs quite poorly compared to the A340 in similar conditions.

The A/THR is a function of the FMGS, much like the FD's or autopilot.