How do i know what flight level to fly at?

when i plan a flight, how do i know what flight level to fly at ?

You can use Flightradar24 to check the altitude of the flight you want to do.

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how do pilots decide what flight level to fly at though?

Think of the term:


North or East is Odd
South or West is Even


Altitudes are given by the airline to the pilots, and it is calculated by weight, winds and direction. Now I could be wrong about this so maybe someone else could answer this.


Generally, you’ll try to fly a turbofan aircraft as high as possible (lowest temp allowable), T/W ratio permitting, as you’ll burn less gas. However, there are circumstances where this will be adjusted due to winds, atmospheric conditions, and routing. Take a look at and find the highest possible altitude with favorable wind conditions for your planned route. You will likely have to compromise between wind and altitude, and remember that there’s no perfect science for it.

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I have an IFATC Education Group Post that’ll explain all this but it’s scheduled for December. Adding onto what @AlaskaAirfireball111 said, it is calculated by weight and many other factors. However, the heading you’ll be flying when you depart tells you possible altitudes you could cruise at.

360-179 is Odd (FL330, FL350, etc)
180-359 is Even (FL320, FL340, etc)


To contribute this can help you. In the picture below. Hope this helped a little.
Good safe flight @BritishPilot !

niveis 1

*I found it in Portuguese, but you can understand the rule.

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I once tried to fly a heavily loaded 777 to FL390. It turned out very unstable and stall warning is frequently given out by the plane. I then lowered the plane to FL320 and it was back to normal.

I think that, due to the lean air at that extreme high altitude, the air mass is insufficient to support the heavy plane. So my experience is, if the plane is really heavy, fly low to about FL320-FL340 only when cruise.

Use FlightRadar 24 or Flightaware to look at the flight you want to fly or similar ones. These sites will give you filed and or flown cruise altitudes for the flight.

Then you can research the cruise ceiling for the aircraft you want to fly. Your upper limit.

As mentioned by another user here, your weight and winds will have an impact on your cruise alt. Particularly on long haul flights when you will be heavy.

This will impact your altitude during your flight. You will see this in your fuel flow and engine performance. Try to stay close to the Average fuel flow indicated in the IF load section and use thrust not over 91% N1 during cruise. Trying to fly too high too soon will cause you to exceed these parameters. So reduce altitude. Step Climbing is in tutorials here in IF

So The starting point is to look for the real world flight levels on the sites mentioned above and knowing your aircrafts cruise ceiling. Then establish your TOW and route distance to see if and how to step climb is needed. Flightradar24 shows a altitude and speed graft of a flight and its easy to see the climb and cruise data.

Lastly as others mentioned your direction East or Westbound will dictate odd or even flight levels

I think there are tutorials about this also.

If you disagree or others have different info please read that


In general yes what happen was you were to heavy probably, but also speed . Sounds like you couldn’t maintain the correct airspeed too

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I remember before the 777 was reworked the physics were really broken

You could get up to 41000/43000 on 100% load and easily maintain speed lol.

Sorry to break the bubble but its safe to say that 100% load will put you over MTOW and climbing straight up to FL430 will put you at the max cruising altitude for this family of aircraft. Thats just not typically done if even possible. FL370 to FL410 is a commonly flown cruise alt. range. This can be backed up by data freely accessable on the internet for performance stats and data on all 777’s.

i usually go onto FR24 and see what altitiude that specific flight is it

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