# Transition Altitude.

Greekman72 Chief Captain

My friends.

In FSPax when i reach about 16000feet co-pilot announce that we reach Transition Altitude.
I would like to ask about an explanation of this.I search net(i admit not too much )but since i know that there are many experts here i pick the easy solution to ask you about it.

Thanks a lot. 😉

CRJCapt Chief Captain

The Transition altitude(TA) is the altitude that you transition from using local altimeter setting to the standard altimeter setting of 29.92 (1013.2 mb). This altitude varies by region. In the US, it's 18,000 ft. In Europe it could be as low as 3000 ft. The actual height of the TA doesn't matter so long as all pilots in the area abide by that TA altitude. 🙂

Manuel Agustin Clausse (Agus0404) Chief Captain

Transition altitude is the altitude in which aircrafts set their altimeter to standar pressure (29.92 in/Hg) or (1013.2 hPa)

Altitudes above transition altitude are measured in Flight Levels. Altitudes below transition altitude are measured in feet.

For example: 16,000 feet is your transition altitude. If ATC wants you to climb to 20,000 feet they would say "Greekman Airlines, climb and maintain FL200"
If ATC wants you to descend to 15,000 feet they would say "Greekman Airlines, descend and maintain 15,000 feet.

Makes sense? 😉

Greekman72 Chief Captain

You are both great

Since i flown with small(unpressurised) crafts and i couldnt pass 12000 feet i have never heard of this message.Now with my Howard i can.Thats why i ask.

Thanks for making a blind man see Gents.. 😉 👍

CRJCapt Chief Captain

Anything for you. 🍻

Greekman72 Chief Captain

CRJCapt wrote:

Anything for you. 🍻

😀 🍻

Bindolaf Captain

From another post:

The number is atmospheric pressure measured in inches of mercury. Atmospheric pressure is basically the force with which the mass of air above you "pushes you down".

Now, because of atmospheric conditions, pressure is not the same everywhere. So, let's say you take off from airport AAA. The "local QNH" or local altimeter setting may be - say 29,75. This is the *accurate local* pressure. Which means, that your altimeter, once set to 29,75 will show you your actual, real altitude.

Now, as you pass 18,000 ft (in the US) you need to switch your altimeter setting to 29,92. Why? Is that the real pressure over 18,000? No. But above that altitude it's not really necessary to know your real altitude. It IS important to know how far you are from other planes though.

Let me give a couple of examples:

Northwest 435 is flying at 18000 ft with an altimeter setting of 29,75
Delta 367 is flying at 19000 ft with an altimeter of 29,84
They converge. Are they really 1000 feet apart? No they are not. Try flying up to 18000 feet and switching from 29,75 to 29,84 and see how different the altitude is. If the difference is higher... there might even be a collision.

So you see, low on the ground, where you have to know your REAL altitude (so you don't run into a mountain), you use the LOCAL altimeter setting (QNH). High up in the skies we ALL use the SAME QNH, so we know where we all fly. Do we know our real altitude? No. Do we know how far apart we are from others really? Yes. And that's what is important.

By the way, 18,000 is the "Transition Altitude" in the U.S. and above that you don't say "altitude" anymore, you say "flight level". Thus, you fly at 17,000 feet, 18,000 feet and then FL190, FL200 etc..

So let's see:

-_----TRANSITION LEVEL (VARIES WITH ATM. CONDITIONS)-----
|
| TRANSITION LAYER
|_
---------------TRANSITION ALTITUDE (ALWAYS SAME) ---------------------

//////////////GROUND///////////////////////////////////////////////////////////

CLIMBING aircraft, set 29.92 (or 1013) passing the TA!
DESCENDING aircraft set 29.92 (or 1013) passing the TL!

Hope it helps 🙂

Greekman72 Chief Captain

Of course it helps dear Bindolaf.
Adding your post to CRJCapt's and Agus's i have a clear view of the point.

Thanks a lot. 👍

Manuel Agustin Clausse (Agus0404) Chief Captain

We will always be here to help 😉

Greekman72 Chief Captain

Agus0404 wrote:

We will always be here to help 😉

I know this very well Captain Agus 😉