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## Transition Level depth

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### Dan created the topic: Transition Level depth

Hello Bob and Stuart,

Im having trouble understanding the difference between the following two questions:

9. The depth of the transition level on this flight would be:

i understand how to get the answer... 11500 - 10270 = 1230

and

25. The thickness of the transition layer when the area QNH is 1028 hPa is

again i understand how to get the answer - 15 x 30 = 450+1000 = 1450

are these questions asking the same thing? what am i missing? .

Cheers Dan.

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### bobtait replied the topic: Transition Level depth

There is no such thing a the depth of the transition level. The transition level is the lowest flight level available for a particular flight. If you found reference to the 'depth' of the transition level please let me know where you found it - it is obviously incorrect. Are you sure you have not misread it?

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### Dan replied the topic: Transition Layer depth

My apologies yes I misread the questions.

The first question asks for the depth of the transition layer

The second asks for the “thickness” of the transition layer...

What is the difference? With the depth question it relates to a QNH of 1004 at a particular point.... the second question just asks what the thickness of the transition layer is if the QNH is 1028...

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### bobtait replied the topic: Transition Layer depth

There is no difference. Depth and thickness refer to the same thing. The vertical separation between the transition altitude and the lowest available flight level.

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### Dan replied the topic: Transition Layer depth

Hi Bob,

This is where I’m a little confused, I understand the first question which relates to the QNH being 1004 which makes cruising at 11,000 not allowed but when the QNH is more than 1013 (1028) wouldn’t the lowest fl available be 11,000?.... the transition attitude is always 10,000 so that’s 1,000 separation...

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