treeny
Posts: 270
Joined: Thu Dec 08, 2005 12:30 am

Airbus And Boeing Throttle Controls

Tue Dec 05, 2006 11:30 pm

Hi All

Before I say anything please dont turn this into an A vs B posting that was not my intention.

I was wondering why Airbus went for throttle levers that remain at idle during flight whereas Boeing's move and respond. Is there any advantage in this in terms of saving fuel like in a car for example where we all now that continuously pressing the throttle consumes more fuel that say, in cruise control.

The other thing I wondered was whether this had any effect on my own opinion that Boeings ride is smoother than Airbus's. It seems that because the throttles react to whats happening it may assist but I am only guessing.

Although the control of thrust I guess is the same or a similar mechanism, does anybody know the reason why the levers move in Boeings design but not in that of Airbus?

Thanks as always

Mark
 
bucky707
Posts: 954
Joined: Sat Aug 19, 2000 2:01 am

RE: Airbus And Boeing Throttle Controls

Tue Dec 05, 2006 11:55 pm

Keep in mind, on the Airbus, though the throttle levers don't move, the engines are still being contolled with the autothrottle.

as to why, I don't know. I like having the throttle levers move. I like the feedback I get, especially when flying without the autopilot.
 
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ThrottleHold
Posts: 545
Joined: Tue Jul 18, 2006 11:00 pm

RE: Airbus And Boeing Throttle Controls

Wed Dec 06, 2006 12:38 am

Quoting Treeny (Thread starter):
I was wondering why Airbus went for throttle levers that remain at idle during flight

They do not remain at idle. They are fixed in the CLB detent. Other than that, they work in exactly the same way as Boeings system.

See http://www1.airliners.net/discussions/tech_ops/read.main/171927/
 
Aviator27
Posts: 332
Joined: Wed Feb 01, 2006 1:09 pm

RE: Airbus And Boeing Throttle Controls

Wed Dec 06, 2006 12:46 am

Quoting Treeny (Thread starter):
I was wondering why Airbus went for throttle levers that remain at idle during flight whereas Boeing's move and respond. Is there any advantage in this in terms of saving fuel like in a car for example where we all now that continuously pressing the throttle consumes more fuel that say, in cruise control.

The other thing I wondered was whether this had any effect on my own opinion that Boeings ride is smoother than Airbus's. It seems that because the throttles react to whats happening it may assist but I am only guessing.

Although the control of thrust I guess is the same or a similar mechanism, does anybody know the reason why the levers move in Boeings design but not in that of Airbus?

Airbus throttles have 4 detents. TOGA (Take-off/Go Around), Flex/MCT (Maximum Continuous Thrust), Climb, and Idle.

For takeoff, the pilot pushes the throttles up to TOGA for maximum thrust, or Flex/MCT for reduced thrust on longer runways or less than maximum weights. At 1000 or 1500 feet, the pilot moves the throttles to the CLIMB detent where they stay for the rest of the flight. Although the FADEC adjusts the engine thrust to maintain airspeed, the throttles do not move. The FADEC can control the thrust from maximum climb thrust to flight idle while the throttle is in the CLIMB detent and the auto thrust is active. During the flare, the pilot moves the throttles to idle.

The throttles are linked to the FADEC (Full Authority Digital Engine Control) by electronic signals, not by cables as in Boeings. This reduces weight (similar to FBW controls). Airbus also has brake by wire, thus extending the weight reduction idea of having no cables extending from the cockpit to the brakes.

Your view that Boeing flies smoother than Airbus is purely subjective and has no basis in scientific facts. In fact, Airbus airplanes are designed for smoother flight with soft altitude hold and load alleviation functions. These are systems that Boeing is now designing into the B787 for the first time ever (they claim its ground breaking). I will add the Lockheed was the first manufacturer to have these functions in their airplanes some 40+ years ago.

Boeing puts a motor into their throttle quadrant to make the throttles move to make pilots feel more comfortable. It has no effect on the actual control of the engines because they also use FADECs. Its the same as Boeing keeping a control yoke instead of switching to joystick. Some pilots feel better grabbing the yoke. This is only because they have never used a sidestick and they feel it wouldn't work. I once flew Boeings and now I fly Airbus and I can tell you, the sidestick is much easier. All my fears about using the sidestick went out the window within minutes of touching the airplane.

These are thoughts and opinions of an airline pilot. I hope I have answered your questions.
 
Tristarsteve
Posts: 3373
Joined: Tue Nov 22, 2005 11:04 pm

RE: Airbus And Boeing Throttle Controls

Wed Dec 06, 2006 3:37 am

Quoting Aviator27 (Reply 3):
The throttles are linked to the FADEC (Full Authority Digital Engine Control) by electronic signals, not by cables as in Boeings

B767 (most of them) B744 and B777 all have electric throttles. But they move under autothrottle control.
 
bucky707
Posts: 954
Joined: Sat Aug 19, 2000 2:01 am

RE: Airbus And Boeing Throttle Controls

Wed Dec 06, 2006 3:40 am

Quoting Aviator27 (Reply 3):
The FADEC can control the thrust from maximum climb thrust to flight idle while the throttle is in the CLIMB detent and the auto thrust is active. During the flare, the pilot moves the throttles to idle.

question for you. If you want, can you turn off the autothrottles and control the thrust manually?
 
larspl
Posts: 351
Joined: Fri Apr 05, 2002 4:06 pm

RE: Airbus And Boeing Throttle Controls

Wed Dec 06, 2006 4:01 am

yes you can, and then the thrustlevers work the same way as ordinary levers.
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EMBQA
Posts: 7798
Joined: Sat Oct 25, 2003 3:52 am

RE: Airbus And Boeing Throttle Controls

Wed Dec 06, 2006 4:58 am

Quoting Treeny (Thread starter):
I was wondering why Airbus went for throttle levers that remain at idle during flight whereas Boeing's move and respond.

Boeing is very much into giving the crew as much 'feel' as they can as to how the plane is acting and responding even as we go to a more fly by wire control.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
troubleshooter
Posts: 420
Joined: Mon Feb 07, 2005 5:22 am

RE: Airbus And Boeing Throttle Controls

Wed Dec 06, 2006 5:29 am

Quoting Aviator27 (Reply 3):
The throttles are linked to the FADEC (Full Authority Digital Engine Control) by electronic signals, not by cables as in Boeings

The CFM56-7B engines on the B737NG are FADEC controlled. Each thrust lever has one resolver assembly with two resolvers (one for each EEC channel) which converts thrust lever position into thrust lever resolver angle (TRA) for EEC (FADEC) input. There is no mechanical linkage between the thrust lever and the engine!
This job sucks!!! I love this job!!!
 
highflyer9790
Posts: 1189
Joined: Thu Jul 07, 2005 1:21 am

RE: Airbus And Boeing Throttle Controls

Wed Dec 06, 2006 12:04 pm

not to go off topic but in boeings, the control coloumn also responds to what the autopilot does where as the airbus joy stick stays motionless.
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wrldwndrer
Posts: 21
Joined: Fri Dec 08, 2006 2:51 pm

RE: Airbus And Boeing Throttle Controls

Fri Dec 08, 2006 3:38 pm

Again, maybe going off topic a bit. How do the throttles on other manufacturers aircraft with autothrottles behave ? Embraer, Bombardier, Dassault, Gulfstream, etc. ?

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