Opt Crz will almost always be below Max Crz so economics should not be a factor.
Err.,, not so simple.
Starting by the fact that in our-days, fuel philosophy aims to upload minimum fuel and the fact that, despite EU OPS 1.255 e) - stating that commanders do have the last word regarding final fuel figures for their flight - there are rumors of crews being under pressure to fly minimum required...
Where is the "freedom" to chose between lower (but safer) levels, when there are turbulence forecasts ahead (sometimes reported to you in the middle of the Atlantic) when you're already half way to your destination?
Whom of us, may heartedly state here, that he has never accepted an Oceanic Clearance, flying Max CRZ levels at the initial part of the flight, fearing to loose Econ Crz for the rest of the crossing?
Aren't we paid to manager the risks? Who has never made a bad decision?
I have. And I'm one of the lucky guys who has learned from bad decisions. All of them seemed OK at the time, but had to be later corrected...
We're talking about strategic decisions, which later on turned to be tactically reviewed.
I'm talking about a tendency, that came with this new fuel and economical crises management stress for survival.
Fly Safe
V