A Q on AutoThrottle

[[email protected]]

Does it get overridden by a manual touch of the throttle, a la Cruise
Control in our cars?

Ramapriya

[Darrell S]

Not quite. You can still move the throttle(s) but when you release them the
autothrottle system (if still engaged) will return the throttle(s) to try to
achieve what you're asking of the system. That could be to obtain and
maintain a given speed or to set a power setting like T.O. Power, Climb
Power, Cruise Power, etc. Some systems have a "clamp" operation where the
throttle(s) can be moved and will stay there until an even occurs which
brings the throttle(s) out of "clamp" and they again try to maintain a speed
or a power setting.

--

Darrell R. Schmidt
B-58 Hustler History: (see below)
http://members.cox.net/dschmidt1/


> wrote in message
oups.com...
> Does it get overridden by a manual touch of the throttle, a la Cruise
> Control in our cars?
>
> Ramapriya
>

[Bob Martin]

Darrell S wrote:
> Not quite. You can still move the throttle(s) but when you release them the
> autothrottle system (if still engaged) will return the throttle(s) to try to
> achieve what you're asking of the system. That could be to obtain and
> maintain a given speed or to set a power setting like T.O. Power, Climb
> Power, Cruise Power, etc. Some systems have a "clamp" operation where the
> throttle(s) can be moved and will stay there until an even occurs which
> brings the throttle(s) out of "clamp" and they again try to maintain a speed
> or a power setting.
>

IIRC, trying to manually move the throttles on a Gulfstream will result
in an autothrottle disconnect and associated amber CAS message.

[[email protected]]

Bob Martin wrote:
>
> IIRC, trying to manually move the throttles on a Gulfstream will result in an autothrottle disconnect.

Makes sense too that way, isn't it?

Cap'n Doug, if you're reading this... I recall clearly, on the one
occasion I was in an A320 flight deck, that the AutoThrottle's
variations weren't reflected in corresponding changes in position of
the throttle. So when you guys want to manually override at some stage,
does the throttle, upon first touch, automatically move itself to the
position where the AutoThrottle has been up to that instant?

It shouldn't happen that you get to move around a throttle that's in
neutral, if you know what I mean :))

Ramapriya

[Capt.Doug]

> wrote in message > Does it get overridden by a
manual touch of >the throttle, a la Cruise Control in our cars?

Depends on the system. Older ATs that move the levers won't disengage. Newer
systems which don't move the levers, such as the A-320, will disengage.

D.

[Jose]

> Newer [autopilot] systems which don't move the [actual throttle] levers...

So the position of the throttle could have no relationship to the engine
power being commanded?

Jose
--
The price of freedom is... well... freedom.
for Email, make the obvious change in the address.

[[email protected]]

Jose wrote:
>
> So the position of the throttle could have no relationship to the engine power being commanded?
>
> Jose


Exactly; at least that's how it is in the A320. And there's no
corresponding movement of the sidestick either when the A320 is rolled
by the AutoPilot (I'm unsure whether there's such movement in aircraft
with yokes).

Ramapriya

[Capt.Doug]

> wrote in message
> Cap'n Doug, if you're reading this... I recall clearly, on the one
> occasion I was in an A320 flight deck, that the AutoThrottle's
> variations weren't reflected in corresponding changes in position of
> the throttle. So when you guys want to manually override at some stage,
> does the throttle, upon first touch, automatically move itself to the
> position where the AutoThrottle has been up to that instant?

With the autothrust off, the FADEC measures the lever angle and sets the
power accordingly. The autothrust function disconnects if the levers are
moved aft of the climb detent. Power is set conventionally with the
autothrust disconnected.

Over-eager pilots new to the Bus occassionally manage to bump the thrust
lever ever so slightly out the detent at inconvenient moments. For example,
coming over the middle marker, the autothrust has N1 set at about 1.05 EPR
(27% rpm) even though the levers are in the climb detent. Bumping one of the
levers just aft of the detent will tell the autothrust to disconnect and the
FADEC will measure the angle and assume you want climb power. When trying to
land on a wet, short runway with limited visibility and a strong crosswind
at max landing weight, having the engines go to climb power is terribly
inconvenient.

D.

[Darrell S]

Yeah, on all the yoke type air carriers I've flown the yoke moves when the
autopilot makes inputs.

--

Darrell R. Schmidt
B-58 Hustler History: (see below)
http://members.cox.net/dschmidt1/


> wrote in message
oups.com...
> Jose wrote:
>>
>> So the position of the throttle could have no relationship to the engine
>> power being commanded?
>>
>> Jose
>
>
> Exactly; at least that's how it is in the A320. And there's no
> corresponding movement of the sidestick either when the A320 is rolled
> by the AutoPilot (I'm unsure whether there's such movement in aircraft
> with yokes).
>
> Ramapriya
>