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-   -   B737-800 only thanks. (https://www.pprune.org/tech-log/451610-b737-800-only-thanks.html)

Scotty Beamup 15th May 2011 01:38

B737-800 only thanks.
 
A question.
You are established in decent using Level Change. If you advance the throttles does the aircraft nose rise (to maintain the target speed) or does the throttle input get ignored.

aa73 15th May 2011 02:18

The nose will rise to maintain the selected airspeed. The throttles are in "Arm" mode.... meaning, your arm controls them. ;)

aussiepilot 15th May 2011 02:19

Nose will come up to maintain selected speed and your descent profile will become shallower due to the lesser rate of decent

esreverlluf 15th May 2011 07:19

It is just like the ab initio "Climbing & Descending" lesson.

In FLCH ,if you push the thrust up, the aircraft pitches to maintain speed. Push the thrust up far enough and it will climb.

de facto 15th May 2011 07:27

Your engines are mounted below the wings,more thrust increases pitch.

ImbracableCrunk 15th May 2011 07:32


Your engines are mounted below the wings,more thrust increases pitch.
Ummmmm. . . . sure. Why not.

Green Guard 15th May 2011 08:01


Your engines are mounted below the wings,more thrust increases pitch.

so even if your engines are in the wings or above the wings the pitch would still increase with power increase because here you are in FLCH mode...right ?

esreverlluf 15th May 2011 10:27

Yes, with low slung engines, the aircraft does get a pitch up moment from increasing thrust, however in FLCH (with the autopilot engaged or manually flying following flight director guidance), the aircraft will pitch to maintain the selected speed.

If the thrust is at idle you will descend. If the thrust is higher you will descend more slowly. If thrust is increased further, the aircraft will level off and with still more thrust will begin to climb. It ain't rocket surgery or brain science!

ImbracableCrunk 15th May 2011 10:39

But at some point, the thrust will increase so much that the plane would just begin to do loops. Luckily Boeing has programmed an Immelman Reversion into the software to prevent this. :}

d105 15th May 2011 11:33

For your information this feature is not unique to the 737-800. Just to avoid confusion.

Capot 15th May 2011 16:00

It all takes me bck to my first lesson in the Autocrat......"now DON'T FORGET; on approach you control SPEED with the ELEVATOR,and DESCENT rate with the THROTTLE. Say after me, I control ......." etc etc.

Now back to you professionals.

Scotty Beamup 15th May 2011 21:42

Thanks.
 
Thanks for the information. I asked because I was assured that this feature did not exist on the 800 and as it is digital it was possible that the EEC ignored the input.
(And for the benefit of one or two above, if you have the auto systems flying the aircraft and advance or retard the throttles the pitch does not change, the aircraft accelerates or decelerates. Only in level change, up or down, does the aircraft changer pitch due to throttle input, and this is to hold the speed, not as a result of engine centerline thrust displacement.

captplaystation 15th May 2011 21:52

Capot,

For an Auster entirely correct, but think you will find for a commercial jet transport in approach configuration that the best/i.e. most rapid, results are realised by controlling speed with thrust & ROD with pitch attitude. The opposite of a tiddler.

Capot 15th May 2011 22:07

It was the phrase

The nose will rise to maintain the selected airspeed.
that caught my eye....."aha" I thought, "the automatics are doing what I was taught to do". But thanks for the info, very interesting.

Capn Bloggs 15th May 2011 23:35


Originally Posted by Playstation
a commercial jet transport in approach configuration that the best/i.e. most rapid, results are realised by controlling speed with thrust & ROD with pitch attitude. The opposite of a tiddler.

Yes, jets are flown the way aeroplanes are supposed to be flown, using the primary effects of controls to achieve the aim. Elevators for flightpath and go-levers for speed control. Tiddlers can get away with doing the opposite, but all you do in a jet is hit the ground faster if you're low and put on the power (737 underslung engine pitch-up not withstanding! :E)

"Always remember and forever take heed, left hand for glidepath and right hand for speed!" Reverse that for effos. :ok:

All this, of course, is for during the approach phase. When said jet is zipping through the air on Scotty's descent, increasing power will make the nose raise eventually when in basic modes.

de facto 16th May 2011 02:45

Is this discussion for a PC SIM player?

It all takes me bck to my first lesson in the Autocrat......"now DON'T FORGET; on approach you control SPEED with the ELEVATOR,and DESCENT rate with the THROTTLE. Say after me, I control ......." etc etc.

Now back to you professionals.
Not on the Jet I fly...:eek:


so even if your engines are in the wings or above the wings the pitch would still increase with power increase because here you are in FLCH mode...right ?
Seriously:p

Capn Bloggs 16th May 2011 02:59


Originally Posted by Defacto
Is this discussion for a PC SIM player?

Obviously you have not spent much time in a light aircraft, because if you had, you would know that flying them using the secondary effect of controls, ie power for slope and elevator for speed, works quite well. In fact, wander into a general aviation airport bar and you'll probably find quite a few pilots that do exactly that.

I have even had "spirited" arguments with instructors on the issue. :ouch:

de facto 16th May 2011 09:15

Isnt the thread title 'boeing 737-800 only thanks'?

lynn789 16th May 2011 23:57

hopefully they werent all asleep
 
  • [*]



A MELBOURNE-bound Qantas plane was forced to divert to Adelaide this morning after crew discovered it did not have enough fuel.

A Qantas spokesman said the A380 from Singapore made the unexpected pit stop around 5am AEST.
He said the low fuel supply was not the result of a leak.
"Engineers have inspected the aircraft on ground this morning in Adelaide and found there were no technical issues," the spokesman said.
"The flight crew found they had burnt through the fuel supplies quicker than expected.
"It was not an emergency landing."
The jet carrying 249 passengers was expected to arrive in Melbourne about 7.30am.

Johnny F@rt Pants 17th May 2011 11:29

Lynn,

I think you're barking up the wrong tree here???


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