LSZH to SBGL / TOGW is 615.6 of which 218 is fuel / FMC Opt FL is given as 305 and Max 325 By the bottom end of Spain Opt is still only 320 and Max 338. This seems awfully low.In the World Air Routes Swiss MD11 video (highly recommended) in both briefings for LSZH-SBGR-LSZH they are fully laden (there is a long discussion about how to get out of Zurich at max weight with terrible tail and cross winds) but still looking for a routing that will give them between 350 and 370 and it appears that they get up to their given max FL pretty quickly.Does flying above Opt burn more fuel in the sim?How come my Max is so low when in the real world they get to go much higher? Is it "normal" to cross the Atlantic so low?ThanksNicholas

Full names please.That is the reason for step climbs, given a heavy load your optimum will be in the low 30's but increase as you burn off weight. This is very realistic.

Nicholas,it is quite common for the MD-11 to start a long haul flight really low, like FL290 to the first step climb! This IS lower than most other heavies out there, but it's what the MD-11 does best, low and fast.A reason to fly above optimum can be if there's much better wind further up, or simply ATC restrictions.Regards,Markus

Thanks for the help.I understand the weight vs climb-height ratio - its basic logic really. What confused me was the Swiss crew talking about FL 350 or 360 in their briefing - when in reality those levels would only be reached much later in the flight.On my flight I was crossing into Brasil when I reached FL350.Nicholas Ferguson