High there! Help!I have had this twice in just as many flights recently: Upon reaching cruise, and 100 ft below, I get "Unable crz alt". This does not make sense to me. It is a normal flight; cruise is set to only FL200 (I find higher altitudes hard to reach (much fuel in tanks) in "short" flights around 200nm)

Fuel planning should eliminate that problem. I made FL310 today on a short 180 nm flight with time to spare. So it can be done :) I had my center tank empty and hardly a drop in the outer tanks, and I landed with plenty to spare.The Unable CRZ ALT messsage comes when the FMC doesn't think that at your current rate of climb the plane will make the cruise alt in time to begin the descent. Try going for a lower cruise alt, or adjusting your fuel to allow for a more lively climb :)

Thank you for response, Clausen (A fine Norwegian name?)The weird thing was, I used the new fuelplanner, and was allready at FL200. The second time, I was merely 100 ft. below, and some miles from T/C..