T/A

[closing from left rpt est]

Hello All,

I was wondering is the T/A in feet or FL?

So in London is it 6000ft or FL60

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Thanks to anyone that replies!!! :)

[Mr Chips]

Feet

[3rd Runway]

give you a clue:

Transition ALTITUDE = feet
Transition LEVEL = Flight Level

[closing from left rpt est]

thanks :)

[HEATHROW DIRECTOR]

The Transition Level is the lowest flight level for use above the Transition Altitude.

[closing from left rpt est]

Right know all about T/A but how do you work out the T/L?

I know it has something to do with the QNH, ie if it is low the T/L is increased.

For example at LL the base of the holds might be raised from FL80 to 90+.

Is there any little rule or is it automated.

Thanks a lot

est

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Thanks to anyone that replies!!! :)

[form49]

The transition level is the first available FL available for use above the transition altitude and is calculated as follows:

QNH = 1000, SID terminates at 6000ft

Altimeter setting 1013 equates to : (6000) + (13 x 30) = 6390ft

The 30 representing ft per mb and the 13 the difference in QNH and 1013

Therefore transition level is FL80 since setting 1013 on the altimeter equates to 6390ft on QNH, to ensure 1000ft separation, first available FL is FL80

QNH = 960 TL = (6000) + (30 x 53 ) = 7590ft therefore TL is FL90

Generally though, its calculated automatically and displayed on the ATIS information screen in the tower.

Hope thats of some help

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Turn left heading 230, close from the left, report established

[This message has been edited by form49 (edited 17 November 2000).]

[closing from left rpt est]

thanks a lot guys (and maybe gals) for ya answers. Will see you up in a tower on centre soon hopefully so watch out!!

Nah thanks a lot

est :)

[x-border]

form49

I was interested in your reply. We seem to do it slightly differently on the other side of the fence (mil). For your example given a QNH of 1000MB, and a TA of 6000' (its actually 3000' where I am), then we would calculate the TL as being the first available FL above the TA, which would be FL65, giving a T Layer of 110', and a Minimum Flight Level for use of FL70.

I understand the rationale ensuring that you have at least 1000' vertical seperation - my question is, why do we do it differently?

[Goldfish Watcher]

I believe the correct answer is a combination of both x/border and form49's answers.

x/border you are right in saying that the transition Level would be FL65 (when QNH=1000mb). The T/L doesn't provide separation, it is the point at which vertical distance is measured in FL's rather than Altitude.

However, the first available Flight level is FL80. Unless of course, in the military, you are authorised to provide 610' separation.

Just my 50p worth
GW

[x-border]

Nope - not 610', but we can take 500' most of the time.

[Goldfish Watcher]

you must be allowed 610 if you can take 500!

But I take your point.

[form49]

G-W, RT taught you well!!!

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Turn left heading 230, close from the left, report established

[closing from left rpt est]

I am sorry but you have really lost me now LOL!

Is any of the last bit relvent or wot? Sorry this is at FL500 and i am still on alt hahaha

see ya 2morow and have a good night all

est :)

[2 sheds]

ICAO permits (or did permit) 4 types of TL, viz

1. Lowest FL above TA, with separation between them (variable with QNH).

2. Lowest FL above TA, without separation between them (variable with QNH).

3. and 4. As 1 and 2, but a fixed, notified TL. This is possible in parts of the world with a stable pressure pattern, though I trust it's reviewed from time to time!

Hence the slightly lose definition of "available for use above the TA" - you pays your money and takes your choice.

[This message has been edited by 2 sheds (edited 18 November 2000).]