Good morning,I would like to know if there is a kind of mathematical rule to find optimum cruising altitude for any particular flight?In other words, how do I decide with FSBuild what will be my altitude to enter for a specific flight?For instance what would be cruising alt between EBBR and LEMD 730 nm compared to WIII-YSSY 2997 nm?Thanks and regardsRakhamToshiba Satellite P4 3.4 Ghz1536 DDR RAM nVidia GeForce FXWinXP Home on the road andPIV 3.4Ghz, 1536 DDR RAM, ATI Radeon 9700 WinXP PROYoke & Pedals CH Products at home

Good evening,And the answer is.....How heavy?RE: Maximum & Optimum Cruise Altitudes table PMDG 2-9.Correct?RakhamToshiba Satellite P4 3.4 Ghz1536 DDR RAM nVidia GeForce FXWinXP Home on the road andPIV 3.4Ghz, 1536 DDR RAM, ATI Radeon 9700 WinXP PROYoke & Pedals CH Products at home

The answer for optimum altitude is roughly where:Thrust Required = Cruise Thrust Available (times a factor of around 95%, for minor airspeed/ altitude corrections).The maximum altitude is where climb thrust provides at best climb airspeed, a rate of climb of 100 feet per minute.

Ok thanks.RegardsRakhamToshiba Satellite P4 3.4 Ghz1536 DDR RAM nVidia GeForce FXWinXP Home on the road andPIV 3.4Ghz, 1536 DDR RAM, ATI Radeon 9700 WinXP PROYoke & Pedals CH Products at home

>The answer for optimum altitude is roughly where:>Thrust Required = Cruise Thrust Available (times a factor of>around 95%, for minor airspeed/ altitude corrections).>The maximum altitude is where climb thrust provides at best>climb airspeed, a rate of climb of 100 feet per minute.Actually you are defining "Service Ceiling". Maximum Altitude is when climb thrust is set with best rate of climb speed and results in no rate of climb.As for the original posters question, the cruise altitudes are based first on your TOGW and then as your fuel burns off you can climb higher. There are tables in the PMDG 744 manual that show optimum cruise altitudes for given gross weights.Cheers,JohnBoeing 727/737 & Lockheed C-130/L-100 Mechanichttp://www.sstsim.com/images/team/JR.jpgwww.SSTSIM.com

As far as I know, service ceiling is the FMC MAX ALT, at least for Boeing. Your correct definition of maximum altitude is out of commercial aviation authorised flight envelope.