Hi PMDG,here it is a question for you:At Heathrow airport (EGLL 09R) with an aircraft load of ZFW=50845 Kg, Fuel=9400 Kg and flaps 5, I've the following calculated takeoff and climbing speed values:FMC N1 LIMITTO-1 DERATE activeCLB-1 DERATE activeFMC TAKEOFF REFFLAPS 5VR=133 KnotsV2=135 KnotsFMC CLBSPD REST 173/FLAPS (which is the climbing speed restriction with flaps 5)MCPSPEED 155 Knots (which is V2+20 Knots, manually set by me)and have the following behaviour:a) imediately after takeoff (positive climb rate) MCP SPEED value is hold at 155 Knots (manually set) and so does indicate PFD magenta Speed Bug.:( when I press A/P ENGAGE CMD A: SPEED value changes to 175 Knots and so does indicate PFD magenta Speed Bug (from where does FMC take this value I don't know)c) when I press VNAV: SPEED value changes to 173 Knots (which is the speed restriction with flaps 5 SPD REST 173/FLAPS) in PFD magenta Speed Bug and MCP SPEED indicator becomes dark.The question is: from where does FMC take the value of 175 Knots when I press A/P ENGAGE CMD A ??? Shouldn't it be equal to 173 Knots which is the SPD REST 173/FLAPS ???Andreahttp://www.precisionmanuals.com/images/forum/800driver.jpg

>The question is: from where does FMC take the value of 175>Knots when I press A/P ENGAGE CMD A ??? Shouldn't it be equal>to 173 Knots which is the SPD REST 173/FLAPS ???When you engage the autopilot on takeoff the first thing it does is bump up your MCP speed by 20 knots. You should have set your MCP speed to V2, not V2+20.Finally, only VNAV mode offers flap speed adjustment. So when you went to VNAV, your FMC commanded the 173 knots.What you should have done was set MCP speed at v2 - 135.Then when you hit CMD A, it would have automatically gone to 155. Then when you hit VNAV, it would adjust to 173 and so on as you retract the flaps.

Many thanks Timothy,very clear!!! I've to set MCP speed with the exact V2 speed displayed in FMC takeoff page.Best regardsAndreahttp://www.precisionmanuals.com/images/forum/800driver.jpg