Don't know if this will help, but if you want to keep VNAV and still select a manual MCP speed, just left click on the center of the speed knob when the cursor turns to a hand. You can then dial in an ATC speed restriction or any other reason you want to manually control your airspeed, yet keep VNAV engaged. I have found that sometimes when really heavy, the VNAV mode will select a higher than 250 KIAS speed when below 10000 and this is the easiest way to over ride the speed the FMS select's.Steve Park

Dear Steve,In my same condition, shortly after coming to 250, the SPD mode has been automatically set (SPD button is lit) to 260 (250+10), to be exact.Sincerely,Kan-ichiro Fushihara

OK,I've just tried it again, at FS9 half speed. I still can not move the speed bug to 250 kts and then engage SPD. If I select FLCH SPD will suddenly engage and then the A/T will give a 250 kt climb. It seems to me that TRC 3 page 3-4 may be misleading. At the end of the day SPD will not engage as instructed in TRC3.RGDSSteve Honey

Would you please try again as below:I have started with PMDG 744 TRC Lesson 3 Part 1.FLT, VNAV off and IAS/MACH set 250.Sincerely,Kan-ichiro FushiharaP.S.I cannot understand why SPD mode has been automatically set.