I noticed something strange when I tried to program the FMC in the 737NG for an arrival into ENBR (Bergen, Norway). From the charts I have all the alt constraints up until the turn for finals are XXX or above. So the first constraint in the FMC was (can't remember the waypoint) 250/FL140A. This caused the TOD mark on the flight path to flash and keep changing from being on the waypoint with /FL140A to a point quite a few nm before it. Obviously the point that was before the /140A waypoint was the correct one but why did it flash and change every second or so?I redid the waypoint to be at FL140 and not /FL140A and this fixed the problem. Any ideas what is wrong? I don't know if it's the way I am doing it or some kind of error.Andy S

The "A" indicates that you are to be above FL140 when passing that waypoint. When you removed the "A" the FMC recalculated the TOD.RegardsRichie

The "A" indicates that you are to be above FL140 when passing that waypoint. When you removed the "A" the FMC recalculated the TOD.RegardsRichie

Yea I know about the "A" already. What I want to know is why it was calculating two different TODs, one correct the other way off.

I noticed something strange when I tried to program the FMC in the 737NG for an arrival into ENBR (Bergen, Norway). From the charts I have all the alt constraints up until the turn for finals are XXX or above. So the first constraint in the FMC was (can't remember the waypoint) 250/FL140A. This caused the TOD mark on the flight path to flash and keep changing from being on the waypoint with /FL140A to a point quite a few nm before it. Obviously the point that was before the /140A waypoint was the correct one but why did it flash and change every second or so?I redid the waypoint to be at FL140 and not /FL140A and this fixed the problem. Any ideas what is wrong? I don't know if it's the way I am doing it or some kind of error.Andy S

You need at last one "hard constraint" waypoint in your plan, if not, the FMC enters a somehow "doubtful state of mind" :( and is not able to calculate an exact TOD point.

Probably because you didn't have a fixed altitude entered on any waypoints after it. RegardsRichie

I thought it might be something along those lines. Thanks for the help anyway guuys. :)Andy S