How to find optimum cruise altitude for ultra long haul flights?

There is no topic about this that came out post global update. For ultra long haul flights being fuel efficient is important, espicially on cross polar, atlantic flights. Ground speed is also another variable. So right now I usually just cruise at FL260 - FL330 depending on terrain (getting best result so far after testing several altitude ranges out). How do you guys go about calculating your altitude?

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There’s a whole bunch of topics about everything surrounding different stages of flight, planning etc in #tutorials - have a look :)

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I fly at FL360-380 as I find the best winds to be there.

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If I am doing a real world flight, I just go off the real world’s flight cruise altitude. If I am doing just any old flight, I just cruise at an altitude dependant on the length of the flight. For long haul probably about 32000ft but it depends on aircraft, speed etc.

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It’s the result of a huge variety of factors. I’m not too sure how many of them are simulated in IF to be honest.

The engines want higher, they are more efficient up there. The wings want lower, they want air to grab hold of. The higher your weight the lower your ceiling. Temperature can also have an effect, high altitude over Siberia in winter can lead to fuel freezing.

Also consider the jet streams. You want to be above or below headwind jetstreams and slap bang in the middle of tailwind jetstreams.

Aircraft type will limit you as well. Typically the 777-300 will cruise at around FL360, stepping up as the fuel burns the weight down. The 777-200 is happier at much higher altitudes, upto FL410.

In my opinion the standard ‘starting’ cruise level for ‘heavys’ on long flights (10+ hours) would be around FL320-340 (take into account semi circular rules) ending at 380-410 prior to descent.

That ‘should’ cover you for the majority of cases and manufacturers.

Edited to add, if you step climb 2000’ from FL320 three times in a flight (divide the flight length by 4 to get your climb points) you will be in the ball park. Same goes for East bound starting at FL330. (8 hour flight/4 gives first step after 2 hours)

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The optimum cruise altitude that you seek is dynamic, many of us utilize sources such as windy.com to plan our cruise altitudes. Also, the links below have everything to do with preparation and planning to maximize fuel efficiency and time. Cheers

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windy.com gives information on where the wind is heading which is useful, but I am not sure how you would use that to plan your altitude. Thanks for the links!

Edit, just found the altitude option, while exploring the site. That will probably be a major factor in deciding altitude for me now.

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I use windy.tv I look at the winds at different altitudes and find what’s best for me, I’ll usually always go above 28000 on anything larger than 1.5hrs