I have made quite a few flights with this fantastic aircraft, and sometimes I get a "ACT LIM SPD CLB" on the climb page of VNAV in FMC. When in this climb mode, the plane will climb maintaining the slowest IAS allowed just above the yellow district of the IAS bar on PFD. I would expect to see an "ECON CLB" mode, in which the plane will lower its nose to accelerate to ECON SPD after passing 10000ft and then climb maintaining this ECON SPD, but in "LIM SPD CLB" mode, the plane will maintain the lowest IAS until getting cruise altitude. And now I get confused. What have triggered the "LIM SPD CLB" mode instead of ECON CLB? Is there anyway I can change LIM SPD CLB mode back to ECON CLB mode? 

 

Please sign your name to your posts - forum rule, thanks.

 

What are you using for controller hardware? Anything that has an unusual way of actuating the gear or flap commands? What it looks like there is the airplane thinking the gear or flaps are out... this can happen sometimes with certain hardware that sends a non-standard command for doing this.

Please sign your name to your posts - forum rule, thanks.

 

What are you using for controller hardware? Anything that has an unusual way of actuating the gear or flap commands? What it looks like there is the airplane thinking the gear or flaps are out... this can happen sometimes with certain hardware that sends a non-standard command for doing this.

I'm sorry for not signing my name...

 

I'm using keyboard and mouse.. I usually take off with 5 or 15 degree flap, and I retract flaps by simply pressing F5 (of course pressing G to retract gear comes first).. Keyboard is not that convenience like a joystick, so sometimes when I press F5 to retract the flaps, the IAS has already passed 200 knots, but it's not overspeed,it's still quite far from the red district. And then, there's chance that the speed mark jumps to the lowest speed allowed and the plane begins to ACT LIM SPD CLB..

 

Ken 

 

 

What it looks like there is the airplane thinking the gear or flaps are out... this can happen sometimes with certain hardware that sends a non-standard command for doing this.

 

The yellow bars will appear on low speed, too, if that's what you're basing that off of.

 

 

 

Is there anyway I can change LIM SPD CLB mode back to ECON CLB mode? 

 

The speed window wasn't open on the MCP was it?

The speed window wasn't open on the MCP was it?

No it's not open... the speed is controlled by computer so nothing is displayed in the window...  If I click on the knob, the number will appear and I can set the speed manually to the ECON SPD, but if I click on the knob again to let computer control the speed, the speed will drop to the lowest again...

No it's not open... the speed is controlled by computer so nothing is displayed in the window...

 

Sounds eerily similar to this:

http://forum.avsim.net/topic/420067-ap-commanding-minimum-speed-on-climb/

 

(the linked post refers to a commanded minimum speed because of a SID selected out of a particular order)

This is exactly what happens to me and seems to be the same as Kyle's link. THR REF/LNAV/VNAV but LIM SPD and I can't seem to get rid of it except to use speed intervene until cruise alt. Doesn't happen all the time so it is likely the SID out-of-order thing. I'm sure they'll fix it in the next update.