Boeing A/Throttle
Thread Starter
Joined: Jul 2002
Posts: 69
Likes: 0
From: A Town Near You
Boeing A/Throttle
The FCTM states: While in manual flight the auto-throttle to be disconnected.
Apart from the apparent reason of forgetting to disconnect prior to touchdown and wondering why the aircraft insists on maintaining VREF+5
Can anyone add some further insight as to why the A/THR has to be off with the autopilot off?
Cheers!!
"Speed Man SPEED!!"
Flex
Apart from the apparent reason of forgetting to disconnect prior to touchdown and wondering why the aircraft insists on maintaining VREF+5
Can anyone add some further insight as to why the A/THR has to be off with the autopilot off?
Cheers!!
"Speed Man SPEED!!"
Flex
Joined: Jul 2001
Posts: 1,611
Likes: 0
From: Gold Coast
Don't know what your airplane is, but that restriction is not applicable to our 747-200s or -400s.
On the Classic the autothrottle is also regulated by the radar altimeter, so that as the aeroplane reaches 0' the throttle is at idle. I think that reduction from bug speed starts at about 30' or so, not sure.
Moderator
Joined: Jun 2001
Aviation Qualifications: ATPL
Posts: 1,492
Likes: 32
From: Blighty
Nope, 777 A/Thr is used until touchdown, where it goes to idle at 20'. SOP is full use of the system. At EK we use manual thrust ONLY in non normal ops, where a checklist might warrant the system off.
EGGW
EGGW
Joined: May 2003
Posts: 198
Likes: 1
From: france
boeing a/t
hello every one,
if mr boeing flight crew training manual (b737), advises to fly manual with a/t off, there must be a reason for it. the reason being : it' s just more simple & easier to do. firstly, as said in a post above, it's mentally, the word manual just mean that: "manual =no automatics" & it' s easy to remember. secondly, it' s also more comfortable for pilots & passengers alike, in that, when you fly manually with a/t engaged, even the slightiest pitch adjustement, yanks the thurstlevers slightly forward or aft, depending on your pitch change & your straight & level flight path more or less resembles a dolphin ondulation.
however it is allowed & advised to take off & climb with a/t engaged, because, once climb thrust is set, the thrust remain fixed & you use manual pitch to control speed, as in your cessna 150. after levelling off manually, you then disengage the a/t & enjoy the delight of manual flight. the emphasis here is : disengage a/t AFTER levelling off, so the a/t reduces to find an average N1 position for the speed you want to fly. you then adjust the thrustlevers manually as required & you are then a real "HOTAS" pilot.(Hands On Throttle And Stick).
regards,
bm,
if mr boeing flight crew training manual (b737), advises to fly manual with a/t off, there must be a reason for it. the reason being : it' s just more simple & easier to do. firstly, as said in a post above, it's mentally, the word manual just mean that: "manual =no automatics" & it' s easy to remember. secondly, it' s also more comfortable for pilots & passengers alike, in that, when you fly manually with a/t engaged, even the slightiest pitch adjustement, yanks the thurstlevers slightly forward or aft, depending on your pitch change & your straight & level flight path more or less resembles a dolphin ondulation.
however it is allowed & advised to take off & climb with a/t engaged, because, once climb thrust is set, the thrust remain fixed & you use manual pitch to control speed, as in your cessna 150. after levelling off manually, you then disengage the a/t & enjoy the delight of manual flight. the emphasis here is : disengage a/t AFTER levelling off, so the a/t reduces to find an average N1 position for the speed you want to fly. you then adjust the thrustlevers manually as required & you are then a real "HOTAS" pilot.(Hands On Throttle And Stick).
regards,
bm,
Joined: Aug 2000
Posts: 265
Likes: 10
From: EU
Just finished a four year stint on the 767. No restriction on the a/t on/off when in manual flight. Personal preference. When the wx is gusty or it is windy, the a/t tends to be a lot more agressive than the pilot would be him/herself. The a/t reacts late in speed reduction, and reacts agressively when speed is low. And these large thrust inputs have a large impact on pitch, this increases workload. So from a passenger comfort point of view I tended to fly a/p-off, also a/t-off. But there was no limitation from our fcom.
Now on the 777, you need a good reason to turn the a/t-off. The thrust vector has been filtered out with the fly-by-wire system in normal mode. So thrust changes have no impact on a/c pitch. Very nice, the 777 is a 767 that has gone to finishing school. Both great a/c, but the 777 is the cat's whiskers.
Greetings O.
Now on the 777, you need a good reason to turn the a/t-off. The thrust vector has been filtered out with the fly-by-wire system in normal mode. So thrust changes have no impact on a/c pitch. Very nice, the 777 is a 767 that has gone to finishing school. Both great a/c, but the 777 is the cat's whiskers.
Greetings O.
Joined: May 2005
Posts: 434
Likes: 8
From: Italy
I fly the B737-700 and in our company is not advised (as per FCOM) to use the A/T with the A/P disengaged, the only exception is take-off and initial climb.
THe B737-700 has a very strong pitch-power couple so I guess it would be very hard to hand-fly if you are not directly responsible of the thrust setting.
I believe the B777 is similar to the Airbus on this issue, very good A/T system together with a fly-by-wire makes your life easier.
Hope this helps
Ricky
THe B737-700 has a very strong pitch-power couple so I guess it would be very hard to hand-fly if you are not directly responsible of the thrust setting.
I believe the B777 is similar to the Airbus on this issue, very good A/T system together with a fly-by-wire makes your life easier.
Hope this helps
Ricky
Joined: May 2002
Posts: 108
Likes: 2
From: FNQ
Due to pilot induced oscillations in response to the change in pitch caused by A/T changes in thrust the general recommendation was to disconnect the A/T system whilst manual flying. However, providing that the resultant pitch changes are anticipated (and thus compensated for) then it is quite possible to hand fly the 767 smoothly with A/T engaged . Keeping your hands on the thrust levers helps!
Joined: Aug 2001
Posts: 755
Likes: 0
From: Europe-the sunshine side
The reason for the recommendation to disconnect the a/t if flying manually is mainly the fact that ,especially at low weights, you may encounter some turbulance at low height (most critical during flare ) and the a/t , sensing AOA approaching alpha floor,will command full thrust very rapidly.
Some of our guys used to keep it in ARM ,untill a few got full power commanded by the a/t,during flare...not a pleasant thing,believe me.
If i/m not mistaken ,the Bus,which uses the a/t to touchdown in 'manual' flight disables the alpha floor protection at some height ( 100',I think)
Yflex: if you keep the a/t on to touchdown ,at 27' it will go to idle thrust,just like on autolands.It has a 'mind' of itself,independent of the autopilot.
Some of our guys used to keep it in ARM ,untill a few got full power commanded by the a/t,during flare...not a pleasant thing,believe me.
If i/m not mistaken ,the Bus,which uses the a/t to touchdown in 'manual' flight disables the alpha floor protection at some height ( 100',I think)
Yflex: if you keep the a/t on to touchdown ,at 27' it will go to idle thrust,just like on autolands.It has a 'mind' of itself,independent of the autopilot.
