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Flight Levels FL...

Wed Jan 09, 2002 9:07 pm

hi i was wondering wether any pilot or anyone could ask something thats been plagued on my mind for a few days now, how do you work out flight level.
eg FL300 is 30,000ft, so how do you work it out in like 3ft or 30ft, thanks.
Its not the fall that kills u, its the sudden stop at the end..
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RE: Flight Levels FL...

Wed Jan 09, 2002 10:17 pm

Flight levels are only used above transition altitude-were the altimeter has the standard presure settings.

I doubt atc would issue cearance to an aircraft in increaments of lees thean 100 ft so the situation should not arise
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RE: Flight Levels FL...

Wed Jan 09, 2002 10:26 pm

I think it is as follows:

during climb, at transition ALTITUDE: from ft. to FL
during descent, at transition LEVEL: from FL back to ft.

correct me if I'm wrong...

I think that in the US the transition altitude is 18 000 ft. In Europe it depends, but when I listen to BRU ATIS, I often hear transition levels of FL 55 and so...


Ivan Coninx - Brussels Aviation Photography
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Maybe This Isn't What You're Asking

Thu Jan 10, 2002 3:17 am

...but: on a standard day the air pressure at 30,000 ft is 4.3641 pounds per square inch. The definition of FL300 is simple: the altitude where the air pressure is actually 4.3641 psi.
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RE: Flight Levels FL...

Thu Jan 10, 2002 3:47 am

Flight levels only apply to altitudes above 18,000 feet. Since all flight above that altitude, up to 60,000 feet, is positive control airspace that means that all flights are under IFR rules. IFR altitudes are cardinal altitudes; i.e, 19,000, 20,000, 21,000, etc. This means that you can have a FL210 (21,000 feet) but not a FL215 (21,500). IFR altitudes are legally divided so that courses being flown (this is simplified) on the "right half" of the compass are odd altitudes and on the "left half" they are even altitudes. ATC can, and does, assign altitudes that do not follow this rule as they see fit.
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RE: Flight Levels FL...

Thu Jan 10, 2002 4:59 am

"Flight levels only apply to altitudes above 18,000 feet", this is in the US only !!!!!!!!!!!!

Since many of the forum readers are non-us personell, I'll point it out, again.....

In the rest of the world the Trasition Level is mostly 2-5 thousand feet above min. sector altitude.

(ex Min.Sector Alt 2000ft => TL40-60)

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RE: Flight Levels FL...

Thu Jan 10, 2002 9:36 am

Uh, Contact_Tower, I was just trying to keep it simple for someone who appeared to be a novice or non-aviator.
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RE: Flight Levels FL...

Thu Jan 10, 2002 12:03 pm

In Australia, transition is 10,000' thur to FL110.

I dont think anyone said this as yet, but when we are flying on Flight Levels, we have 1013.2 set on the subscale, or 29.9 (correct me if Im wrong ) depending which scale the altimeter uses!
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RE: Flight Levels FL...

Thu Jan 10, 2002 4:28 pm

29.92 is the standard barometric setting.
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RE: Flight Levels FL...

Thu Jan 10, 2002 5:30 pm

Hi Planespotterx.

As stated before, altitudes above "transition level" are known simply as "flight levels".
All you do is drop the last two zeros.
Therefore, "30000 feet" becomes "flight level 300", "25000 feet" becomes "flight level 250" and so on.
Is that what you were after?

Transition level is where the pilots set their altimeters to the "standard altimeter setting" which is 1013.2 millibars or 29.92 inches of Mercury (depending on which scale is used in any given country) when climbing and to the local altimeter setting (Qnh) when descending.

Transition level differs around the world.
In the US, it's 18000 feet. In the UK it's 6000 feet. And here in NZ it's 11000 feet.
Hope this helps!!

Mike-NZWN  Smile

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