737 FCC Software change

[Jwscud]

i understand that Boeing are updating all new 737s with FCC software that removes the manual override to CWS feature. Any manual override of the controls will automatically disengage the autopilot rather than (as previously) trip the pitch or roll channel to CWS.

Any ideas as to why they chose to do this? I was quite a fan of CWS pitch if the aircraft captured an altitude at ALT ACQ with a daft rate of climb in busy airspace amongst other uses.

[B737900er]

Im wondering when the FMC software 11.0 comes out.

[FlyingStone]

Boeing's Bulletin:

BACKGROUND INFORMATION
737 service history indicates that flight crews may not recognize or correctly interpret the autoflight system automatic transition to the Control Wheel Steering mode.
Automatic transition to CWS may occur while engaging the autopilot or when it is already engaged. Examples are attempting to engage the autopilot while not following the flight director commands, or force override through the control column or wheel with the autopilot engaged. The reversion to CWS mode may not always be easily recognized by the pilot

You can still use CWS P in the altered FCC software by disengaging the current pitch mode (e.g. press VNAV in climb).

FMC U11 should be released in first half of this year.

[Avenger]

And the other bit: Applies to Rockwell Collins autopilots, line number 5234 scheduled for delivery Jan 2015 and subsequent production airplanes will incorporate the changes to automatic transition to CWS..

[172_driver]

In times when I've ended up in CWS P - either due to finger troubles or a computer glitch - I've sometimes found it easier to disengage everything and to later re-instate the automatics (if needed).

The missing FMA and amber CWS can be a bit of a handful to correctly interpret at times when things happen fast, e.g. capturing LOC or approaching an ALT.

So to an extent I agree with the BACKGROUND INFORMATION

[Jwscud]

Well that makes sense. Our company didn't provide us with the full Boeing background, so it does make a bit more sense.

ALT ACQ is an automatic transition mode and thus you can't deselect it, which was when CWS was rather useful. Apart from that, like others I probably see it occasionally when accidentally pressing LNAV twice or something like that.

[cosmo kramer]

BACKGROUND INFORMATION
... The reversion to CWS mode may not always be easily recognized by the pilot ...
How are 2 bright blinking yellow lights difficult to recognise? :confused:

[JeroenC]

When deselecting VNAV etc, do you still have ALT ACQ capability? Manually selecting CWS PITCH doesnt. I would rather Boeing had added to autopilot disconnect audio signal. But hey, I'm not the one paying Boeing;)

[FlyingStone]

FD + CWS P = no ALT ACQ feature
CMD + CWS P = ALT ACQ feature

In the old FCC, you can go to "CMD + CWS P" either by deselecting pitch mode or by pushing/pulling on the control column. With the new FCC, appareantly the only way to do this is to deselect the pitch mode.

Personally I find CWS P very good tool during the last levels in climb when heavy - to avoid over-sensitive pitch oscillations of the VNAV SPD mode.