Airbus ATHR

[rich49]

Hi all,
Could someone take the time please to explain the A/THR on the Airbus? I have a complete A340 FCOM from Airbus and I still can't understand one point, it's doing my head in!
I understand most of it, I will explain some of it and then ask some questions.
So: The A/THR can be ARMED by: On the ground: pushing the A/THR button when the engines are powered down or by moving the TL to the FLX/MCT or TOGA detents OR: In Flight: By pushing the A/THR button when the TL are OUT of the ACTIVE range or by moving the TL past the CLB detent.
The A/THR can be ACTIVE by: pushing the A/THR button whilst the TL are INSIDE the ACTIVE range or by moving the TL between IDLE and the CLB detents but only if the A/THR is ARMED first. When the A/THR is active the thrust or speed is controlled by the various computers (lets not go into this one yet!) upto either: a)the max TLA or b) the detent.
Of course the thrust may be controlled manually were the thrust is proportional to the TLA provided the A/THR is not active or armed, and if the levers are moved into a detent then the thrust is set to the detent value set in the FMGC.
SO: my question is this:
I want to control the thrust manualy, I command 50% power so I move the TL half way up the quadrent. Fine so far, but then I want maximum power so I move the TL to the TOGA detent, the power goes to max and the A/THR arms itself (as above). Then I want to bring the power back down again and resume manual control but as I bring the TL back down into the active range (beteen CLB and IDLE), because the A/THR is ARMED first it now goes to ACTIVE.
So in other words I keep having to push the instinctive disconect buttons when controlling the thrust manually if I go to full power and back.
Could someone explain?
Cheers
Ric

[LEM]

Userfriedly, isn't it?

Hahahahahaha!....

Just kidding, Rabbit! ;) :D ;) :D ;) :D

LEM

[rich49]

Hmmm well, if you get too fed up I suppose you could just push the instinctive disconnect buttons for 15 sec....

[Fat Dog]

I'm a Boeing driver, so what does the 15 sec push do? Don't tell me it REALLY disconnects the A/T and turns it into a (semi) real airplane like a Boeing? ;)

[End_of_Descent]

Fat Dog,

> Don't tell me it REALLY disconnects the A/T ...

It does...

A330 FCOM p1.22.30

"CAUTION

If the pilot pushes and holds one instinctive disconnect pushbutton for more than 15 seconds, the A/THR system is disconnected for the remainder of the flight. All A/THR functions, including ALPHA FLOOR, are lost and they can only be recovered at the next FMGC power-up (on ground)."

Disconnect PB is either on the throttles or on the FCU (=MCP)

EoD

[idg]

rich,
Indeed the autothrust will go active (once you come back to the CLB detent on all engines or the MCT detent on an engine failure) but bringing the thrust levers below either of these two positions will just limit the thrust manually.

One thing to remember however is that if the speed (managed or selected) is below your current speed then the thrust will go to idle.

Assuming this is not the case all that will happen is the thrust will follow the 'doughnuts' and other effects are dependant on the mod state of the a/c.

On ours we now get a chime every 5 secs or so and an ECAM warning that the thrust is 'limited'. Our FCOM specifically warns not to use full flap at high weights when flying level due to the large thrust requirements.

The implication is that of course selecting TOGA (as in your example) will also activate the FDs into the GA phase. Thus if you were set up for an ILS intercept, selecting TOGA will have the FDs cancelling the ILS and intercept. It would then require some nifty button pushing to get things back on track. Or of course one could turn off the flight directors and fly raw data.

;) idg

[RadarContact]

Just to confuse things (or maybe clarify a bit ;) ):

ATHR ist only armed when taking the thrust leverst back to CLB after settings TOGA for takeoff or go-around.

If in any other flightphase you decide to set TOGA (be it out of autothrust or manual thrust), autothrust will be disengaged and not armed!

Meaning: As long as you are in manual thrust and don't engage the go around mode (as during the approach) you will stay in manual thrust mode.

[overstress]

:confused: Why would you want to keep going from TOGA power to idle and back??

[LEM]

Just for fun!:p