I've been flying the queen for quite a while with no real problems, and now for some reason it's not flying correctly and I do not understand why. I'll try to explain the problem.After takeoff with VNAV armed, THR REF and VNAV SPD annunciate green on the FMA, but the speed bug only increases by a couple of knots and does not make it above the flap manouever speed. (won't fly fast enough to allow flap retraction).I've wracked my brains to try and work out what could be causing this and I'm stumped!-AC is well under MTOW-The speed window is clear (ie no speed selected inadvertently)-Accl height set to 1000ft and FMC set up correctly.-No speed constraints on the CLB page or LEGS page.-V2 set in the speed window before takeoff roll.If anyone can help I'd be very grateful, this is very frustrating!Regards,Martin Neep

Martin when this happens can you take a look at the VNAV climb page and take a print screen shot of it then post it here.CheersSteve

EO accel set to 1000ft, but Flaps/xxxx . . . set to "xxxx" = "way up there."maybe?

Hi,I had a similar problem, the speed in the climb stayed at 170 knots and it wouldn't accelerate for flap retraction.The problem only appeared when an approach was also entered in the FMC. If this is your case try one of the following:- delete the approach- OR if you don't want to delete the approach, try at least to delete the approach speed restrictions around the FAF. Don't worry about approach speeds in the climb, you will be able to enter them in later on in the cruise, when planning the approach.Please let us know if this fixes your problem.Cristi