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Why did we pick TL 18.000ft?

CaptLeslie

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18,000 feet is the fixed transition level in the US?
Europe is considering having a fixed level. Some have suggested 10.000' while others say – lets do the same as the US.

Does any of you know why we picked exactly 18.000 feet and not another fixed altitude?

Can you see any advantages or disadvantages of having a lower fixed transition level – for example 10.000ft?
 
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727gm

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I have heard that it used to be 24000 ft and that they were going to lower it to 12000 ft, and that 18000 was the compromise. It's at least 3000 ft above the highest point in the 48 states, so cold, low pressure should never have you too low anywhere above transition.

Other countries have lower transition level, true, but those other countries don't have GA, and never will.....at least anything like we have in the USA.

The main disadvantage would be the requirement to be on an IFR flight plan. Would be VERY bad for soaring, ballooning, and general aviation in general....

Or did you mean transition ONLY, not Class A also?
 

milky

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It's lower in Japan, but you can fly VFR at any altitude.

"Hawk11 request direct Iwakuni"
"You're creared directo hooke then directo Iwakuni"
"Hawk11 cancel IFR"
 

Coool Hand Luke

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18,000 feet is the fixed transition level in the US?
Europe is considering having a fixed level. Some have suggested 10.000' while others say – lets do the same as the US.

Does any of you know why we picked exactly 18.000 feet and not another fixed altitude?

Can you see any advantages or disadvantages of having a lower fixed transition level – for example 10.000ft?

Because unlike in Europe I can actually fly VFR somewhere in my airplane and have the ability to enjoy a nice tailwind and burn less fuel in my friends Mooney Ovaition like I did last night. Went up to 11,500 and were doing 185 KTAS on 14 GPH. In Europe I'd be down below 10, going slower and burning more gas. Which brings up my point. Why should we do whatever ICAO does? Not everything they do is better. Obove case in point.

Why not file and fly IFR you say? Because it was CAVU and I wanted to enjoy some nice music, that's why.
 

ak_pilot

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Dont forget about us up here in AK. We are part of the U.S. too.

Mount McKinley 20,320 Ft.

ak_pilot
 

Be 23

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Wasn't it established before Alaska counted?

FWIW, pushing it up to 22k (and the class A floor with it) would be great for a lot of glider pilots.
 

keebird

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Because unlike in Europe I can actually fly VFR somewhere in my airplane and have the ability to enjoy a nice tailwind and burn less fuel in my friends Mooney Ovaition like I did last night. Went up to 11,500 and were doing 185 KTAS on 14 GPH. In Europe I'd be down below 10, going slower and burning more gas. Which brings up my point. Why should we do whatever ICAO does? Not everything they do is better. Obove case in point.

Why not file and fly IFR you say? Because it was CAVU and I wanted to enjoy some nice music, that's why.

You're getting transition altitude and class A airspace mixed up. Different things that just happens to coincide here in the the US.
Even if transition altitude was lower, there is nothing that would prevent you from flying VFR at FL115.
 

Coool Hand Luke

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You're getting transition altitude and class A airspace mixed up. Different things that just happens to coincide here in the the US.
Even if transition altitude was lower, there is nothing that would prevent you from flying VFR at FL115.

No, I understand the differences.

I'd be interested in some examples of where the transition altitude doesn't also preclude IFR flight?
 

WMUSIGPI

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Look at Europe. Some places the transition level is in the single K digits. Also some airports have class A airspace (IFR only)
 

Stby One

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I really wish we would raise it in europe to at least 10000 feet. A SID with initial Flight Level 40 with low altimeter setting is asking for a level bust. At Birmingham they have to add a message on the ATIS reminding pilots to set STD early to avoid level bust when the QNH is low.
 

jafo20

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Cool Hand, you can fly VFR over France in the mid teens, even though you're above transition altitude. In most places, being above transition altitude doesn't preclude VFR. Knowing where you can be VFR and where you can't gets complicated when you're crossing numerous FIR boundaries and national borders. Sticking to "No VFR at night or above transition level" generally keeps things easy.

If you find yourself routinely looking for VFR for the specific circumstances of your assignment (For example, supporting operations at private, uncharted airports in numerous different nations. Or you may find yourself looking to shortcut around extremely circuitous local airway structures.) You can see exactly what you can do in your Jeppesen Airway Manual, local publications, AIS officers, etc.

Stby One makes an AWESOME point with respect to transition altitude/level. Most of the time controllers are pretty good about saying "Climb to and maintain X thousand feet or flight level X.". When they don't, you really have to pay extra close attention to your altimeter settings. I haven't busted an altitude abroad yet, but I probably will in the near future.
 

Mercy98

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The reason for FL180. This is what I recall.

In the old altimeter days of the round dial, that is the mechanical makeup of the instrument itself (the bellows and comparison of ram and static air), the errors were too great between individual altimeters above 18,000ft.

It was decided that all aircraft flying above that altitude should be on the same setting regardless of location. The errors would be minimized that way.

Why do other countries use a different altitude? I guess it's just that...to be different. Perhaps with an added measure of safety involved since they use lower transition altitudes than us.
 

pilotyip

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because 060 used at BDA was too low
 

Donsa320

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The reason for FL180. This is what I recall.

In the old altimeter days of the round dial, that is the mechanical makeup of the instrument itself (the bellows and comparison of ram and static air), the errors were too great between individual altimeters above 18,000ft.

It was decided that all aircraft flying above that altitude should be on the same setting regardless of location. The errors would be minimized that way.

Why do other countries use a different altitude? I guess it's just that...to be different. Perhaps with an added measure of safety involved since they use lower transition altitudes than us.


Well, we flew just fine above 18,000ft for many years with "round" altimeters. The real problem was, as speeds increased wth jets, "current" altimeter settings could vary greatly in a short period of time. With rather infrequent radio contact the difference could be a problem. Two thousand foot increments helped but a standard setting helped most.
BTW ram pressure is not a factor in baro. altimetry, just static.

DC
 
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