Changing to lower FL during flight ?

[Christian Martensen]

Do you always change to a lower FL when FMC recommends? When you do, and when not?

Example: I was enroute, FL380, at some point still in cruise with plenty of miles to go, FMC recommended FL340. I understand that this might be a calculation based on the weather, winds etc.

I am thinking that the plane  is consuming less fuel at the higher FL, and therefore it wouldn't make sense to descend to a lower FL, unless there´s HUGE advantage to be gained.

Any insight is highly appreciated.

Thanks!

 

[Hampus Norrby (1329366)]

Now, I'm not a pilot but the most optimum flight level is based on many different factors such as winds, the weight of the aircraft, traffic and so on. In this case, my guess would be more beneficial winds on FL340 compared to FL380, hence FL340 would be more efficient.

[Martin Loxbo (811805)]

What aircraft are we talking about? I've never seen an FMC "recommending" a lower level, unless we are talking about a level restriction as part of a STAR (or manually entered). Your optimum flight level will increase during the flight as the weight decreases as fuel is burnt off. Normally the only reason to descend to a lower level would be more favourable winds, unless we are talking about just a 1000 ft decrease in order to comply with odd/even levels.