Took a break and went to the NGX again and I think I never had this before, OPT FL396 MAX FL391.

I'm not 100% sure now but I think I saw the MAX at FL402, so I came back after some minutes, changed the MCP to 40,000 then popped up the FMC to confirm the climb and then surprise, it showed MAX 390, what happened?

 

Kept her at [email protected]

 

Thanks

If you seen that before departure, you could have made that level by ToC by virtue of weight loss from fuel, probably.

 

About MAX level change, changes in environmental factors can trigger a change in maximum level. Things like temperature.

 

 

I'm not 100% sure now but I think I saw the MAX at FL402, so I came back after some minutes, changed the MCP to 40,000 then popped up the FMC to confirm the climb and then surprise, it showed MAX 390, what happened?

Interesting, I have never noticed the optimum below the max! I can say that in real life positive ISA deviations in the climb can have an instantaneous and considerable effect on the max altitude. I'm guess FSX wouldn't really model such variances by default, so I presume you are using a third party weather app that uses real world data?

 

 

If you seen that before departure, you could have made that level by ToC by virtue of weight loss from fuel, probably.

I saw it at FL380 then left for a little while and something must've happened in between I think.

 

 

Interesting, I have never noticed the optimum below the max! I can say that in real life positive ISA deviations in the climb can have an instantaneous and considerable effect on the max altitude. I'm guess FSX wouldn't really model such variances by default, so I presume you are using a third party weather app that uses real world data?

I had never seen it before as well, I use the freeware FSrealWX lite for weather, a bit unstable but acceptable I guess.