ixeg fmc showing unable crz alt after changing arrival procedure or rwy

[tobiaspopp7]

Hello everyone i need help with my ixeg i know that project is forogten but why not:D. So when i change rwy or arrrival procedure my ixeg say "undable crz alt" that would be okay if my plane start accelerate very fast and vnan stop working plane dont repsond to anything when i change something it fmc it just respond by "unable crz alt" and that is all so i have to descend and chage speed manualy and it starting beeing very annyoing thx for response (sorry for some grammar i dont know english very well)

 

[Cameron]

@Litjan will be better to answer this, but as I recall, this error presents itself when you choose a cruise altitude too high to achieve for the length of the route. Selecting a lower cruise altitude should resolve this.

As a side note, the project is not forgotten or dead.

[Litjan]

Yes, Cameron is correct - when the plane calculates that it won´t be able to reach it´s cruise altitude and then descend again in time for the landing, this message will appear.

It can also happen that a different STAR or SID has an altitude restriction on it, that makes it impossible to reach the cruising altitude.

When you change a SID or STAR while you are already flying another one, VNAV can get confused about the phase of flight it is on (climb, cruise, approach)

[tobiaspopp7]

On 8/6/2025 at 12:12 PM, Litjan said:

Yes, Cameron is correct - when the plane calculates that it won´t be able to reach it´s cruise altitude and then descend again in time for the landing, this message will appear.

It can also happen that a different STAR or SID has an altitude restriction on it, that makes it impossible to reach the cruising altitude.

When you change a SID or STAR while you are already flying another one, VNAV can get confused about the phase of flight it is on (climb, cruise, approach)

okay thx for response i very appreciate that