My one gripe with this aircraft is my inability to accurately control it's pitch. To engage the A/P one flicks both the Roll/Pitch bars into the engage position. This is fine.

However, I do not understand the CWS system. It continually fights me and always wishes to return to the previous held pitch. Only by disengaging the pitch hold mode do I get control again, but this bypasses the point of CWS in the first place.

Can somebody explain to me how the CWS and pitch select on the autopilot works? Yes, I have read the manual. But for somebody used to NG's and J41's the steam gauges of the 737 are a world away (in fact I've grown very quickly used to it, just not the pitch commands).

Thanks

Raff

I have the same problem. It usually takes about 5-10 times moving the yoke before it will decide not to fight against me.
Obviously this is without Alt Hold engaged.

I guess I can only describe how it works here. I turn it on, it holds the pitch, I pull on the joystick some more, aiming for e.g. 5 degree up and let go again. I can hear the AP trimming to hold the pitch I've established with pulling on the stick. This takes a second or so, one can see the trim wheel spinning.

That's for increasing the pitch, but the decrease works the same way. Force it to a new pitch attitude, let go and see the AP trying to establish the commanded attitude with trimming the plane. When it's done, you will grab the stick and feel that the out of trim forces are gone. You are 'in trim' on the new attitude.

Perhaps the vital part is the pull to new attitude and then let go. But I'm on a FF stick, so I don't have a spring or something forcing my stick to centre no matter what, I just work with or against the real trim of the plane. Don't know if that adds to the problem or not.  :-? Works fine here. Bit of a poor man's FBW.  ;D


lagraf05 wrote on Jul 13^th, 2012 at 10:43am:

Can somebody explain to me how the CWS and pitch select on the autopilot works?

Just in case, that pitch select knob is just for the FD. The AP doesn't mind, it just 'looks' at the yokes.

I've managed to figure it out :) I give it a small twiddle either up or down, this seems to release the hold the AP has over the elevators, then it allows me full control over the pitch. Works like a charm.

Sounds good. Lets call it the twiddle mode.  :D

Southwest Flight 209 crash report summary:

It has been determined that pilot error was the cause of the crash that killed all 126.3 onboard.

Pilot did not twiddle flight control, resulting in the AP CWS maintaining pitch until the aircraft stalled 1.5 minutes after taking off. Only a brief communication between the pilots was recorded:

10:32:01 pm --  Pilot: Bloody hell, this piece of ....

10:32:05 pm -- Copilot: Twiddle, twiddle!

10:32:07 pm -- Pilot: What?

10:32:09 pm -- Copilot: Twiddle. You might need to twiddle. (stall warning horn in background)

. . . . . . .

10:32:18 pm -- Pilot: What?

10:32:19 pm -- <radio static>

bud7h7 wrote on Jul 13^th, 2012 at 9:18pm:

Southwest Flight 209 crash report summary: It has been determined that pilot error was the cause of the crash that killed all 126 on board. Pilot did not twiddle flight control, resulting in the AP CWS maintaining pitch until the aircraft stalled 1.5 minutes after taking off. Only a brief communication between the pilots was recorded: 10:32:01 pm --  Pilot: Bloody hell, this piece of .... 10:32:05 pm -- Copilot: Twiddle, twiddle! 10:32:07 pm -- Pilot: What? 10:32:09 pm -- Copilot: Twiddle. You might need to twiddle. (stall warning horn in background) . . . . . . . 10:32:18 pm -- Pilot: What? 10:32:19 pm -- <radio static>

Outstanding! Cracked me up completely. LMAO! ;D ;D ;D

;D Told you this guy would be dangerous.
http://affordablehousinginstitute.org/blogs/us/wp-content/uploads/2007/10/imagesairplane-otto-small.jpg
http://www.desipio.com/?p=1746

And I guess those guys just showed how to deal with some situations.
http://www.youtube.com/watch?v=uSlXHkReTD0

From here on in, the CWS shall be renamed the "twiddle steering method."

I feel I may have inadvertently given rise to a new aviation meme. Thanks for the jokes and help everyone :)

Well, as you saw in Bud's post, the technique already is part of any 737 emergency checklist.

Quote:

Loss of control checklist 1) hydraulic pressure > check if present 2) stab trim setting > adjust to typical cruise value 3) twiddle > no matter what 4) re-twiddle if necessary 5) keep on twiddling

That's from an official Boeing doc, trust me.  8-)

They've revised that checklist quite often. The first one just read

Quote:

Slowly apply pressure to .. your FO to handle the situation, dammit!

 :o

CoolP wrote on Jul 14^th, 2012 at 11:42am:

Well, as you saw in Bud's post, the technique already is part of any 737 emergency checklist. Quote: Loss of control checklist 1) hydraulic pressure > check if present 2) stab trim setting > adjust to typical cruise value 3) twiddle > no matter what 4) re-twiddle if necessary 5) keep on twiddling That's from an official Boeing doc, trust me.  8-) They've revised that checklist quite often. The first one just read [quote]Slowly apply pressure to .. your FO to handle the situation, dammit!

 :o
[/quote]
STOP! I'm splitting my sides in laughter and it hurts! Enough! >:(


WAIT! No, DON'T STOP. The pain in my sides is not as bad as my usual pain! Joke away! ;D ;D ;D