What does FL300 mean?

Hey, so I have been seeing this abbreviation a lot in IF, and I am really confused on what it means. Does it mean that I need to fly at 300 feet or something? But that seems really weird…

In short, 30000 feet

Add 2 0’s behind the flight level number and you get the altitude


Okay thanks. Got really confused there…

30000 feet
FL500=50000 Feet
FL400=40000 Feet
FL300=30000 Feet
FL200=20000 Feet
FL100=10000 Feet

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Thanks for the help guys. So, basically its just that number, but thousand instead of hundred?

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To add on to Josh…

FL050 - 5,000
FL180 - 18,000
FL340 - 34,000


Great opportunity to do some learning here while were at it…

when you are flying at or above FL290, you will fly at odd altitudes going east and even altitudes going west. This means:

from a heading of 0-159, you’d fly at FL290, FL310, FL330, FL350 and so on, going west, 180-359 would be at FL300, FL320 and so on!


Pardon me but if I’m not mistaken…IF IM NOT MISTAKEN, I have heard and seen that one ford not use flight level below 18,000 feet. It’s be wrong but I just want to be corrected if mistaken.


Aside from being an abbreviation for altitude, FL’s are also used for standard QNH/Altimeter of 1013/29.92, whereas you would use XXXXft regardless of the altitude if you’re below the transition altitude/level. The transition level, however, varies between countries.

Depends on the transition altitude. In the USA this is 18,000ft, however it various elsewhere. For example in the UK it’s 6000ft, whilst in Norway it’s 7,000 ft. Lots of different factors affecting such as height of terrain as well as barometric pressure etc.

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Hang on, can you run through that again, just in simpler terms? So if you are about 28,000 ft you fly at odd numbered altitudes going east, and then even numbered altitudes going west? That doesn’t make any sense.

Ohhh I see now. Very much appreciate the info. Guess I know something new today!

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That make sense?

edit: i’d link you to the IF tutorial guide on this, but its incorrect. Search aircraft cruising altitudes on google and you’ll find a lot of info


Flight Levels don’t start until 18,000, you wouldn’t use FL050, just 5,000 feet.


This is a complete IF myth.

Flight levels are based on having 1013.7hectopascals or 29.92 inches set.

You can have those pressure settings in the kit down at 2000ft and effectively be at FL020. If you set a different QNH then you are in thousands of feet.

In IF, if you’re setting 2000ft on your AP, you’re established at FL020 however if you’re taking your height from ground level then you’re working thousands of feet.

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In the US it starts at 18,000ft however it varies in other countries.

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Ok I’d really like to clarify some things with you on your topic since you are getting a lot of scattered information some accurate some not.

First off your main question what is a Flight Level FL is your altitude when the pressure setting on the altimeter is set to 29.92 inhg or 1013 bars. Also known as Standard pressure / Pressure altitude. In the US we use this standard pressure at and above 18,000 feet. Prior to 18,000 feet you use the actual barometric pressure. Resulting in the actual altitude above sea level. In the US once at or above 18,000 feet everyone uses standard pressure settings thus not being your actual altitude above sea level, but it’s now a Flight level

Now onto the altitude reference given for direction of flight. For a westerly course 0°-179° you will fly even thousands 4,000 6,000 and so on. For an easterly course 180°-359° you will fly an odd heading 3,000 5,000 and so on. For VFR Flight you fly the same but add 500 ft to each of these. Now at or above FL290 you will increase these by 4,000 feet instead of 2,000. FL290 FL330 and so on. The exception to this is in RL you have RVSM certified aircraft in which case you can just increase it by the standard 2,000 all the way up. For IF we’re we have no altitude reporting anomalies this can also be used.

Now you will notice I used the word course instead of heading for this. Course is your direction tracked across the ground. Heading is the direction your aircraft is pointed in. These two are not always the same. If you have a 0 wind condition they are, but as soon as you start adding any cross wind to the equation they begin to differ. When this happens you need to compensate for the wind to maintain the correct course.

If you have any questions feel free to ask. This is the complete answer to all that was asked and stated above ✌️


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