FL flying
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Joined: Jul 2006
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From: UK
FL flying
At what altitude do you change to FL instead of flying on a region pressure?
Do you change automatically at 5000ft or is it your decision whether you fly at the regional pressure (i.e. Barnsley QNH)
Do you change automatically at 5000ft or is it your decision whether you fly at the regional pressure (i.e. Barnsley QNH)
Joined: Aug 2007
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From: UK
Joined: Oct 2006
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From: Ooh arrgh land
Depends where the transition level is on the day (the transition layer changes with pressure alt), if you were flying IFR in the UK you would change to 1013.2mb/hpa at 3000' QNH.
Now, if you are VFR, you can do that (and fly quad levels etc), but I have flown on the QNH around and about at 4000' quite happily.
That's my understanding, but I'm probably wrong (I don't have the book to hand) so someone, please put me right!
Now, if you are VFR, you can do that (and fly quad levels etc), but I have flown on the QNH around and about at 4000' quite happily.
That's my understanding, but I'm probably wrong (I don't have the book to hand) so someone, please put me right!
Joined: Oct 1999
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From: Anywhere
Flight Levels are mandatory for IFR flights above Transition Altitude.
Transition Alt is 3000ft in the UK FIR's, but higher within most CTA's / TMA's (London and Scottish - 6000ft, East Midlands 4000ft etc - all available in the UK AIP ENR section under Altimeter Setting)
Go elsewhere it can be higher - USA is 18000ft.
Flight Levels are only recommended for VFR flights above Transition Altitude.
So - the answer to your question - if you are going to change, or need to change, you change at Transition Altitude.
As a footnote - Regional Pressure setting. DO NOT use this if you are in the vicinity of Controlled Airspace where the base level is defined as an altitude. YOU WILL INFRINGE.
You should be on the QNH of the airport concerned or a nearby one to ensure you remain outside CAS. Personally I only use RPS if there is nothing else available - which is very rare.
Transition Alt is 3000ft in the UK FIR's, but higher within most CTA's / TMA's (London and Scottish - 6000ft, East Midlands 4000ft etc - all available in the UK AIP ENR section under Altimeter Setting)
Go elsewhere it can be higher - USA is 18000ft.
Flight Levels are only recommended for VFR flights above Transition Altitude.
So - the answer to your question - if you are going to change, or need to change, you change at Transition Altitude.
As a footnote - Regional Pressure setting. DO NOT use this if you are in the vicinity of Controlled Airspace where the base level is defined as an altitude. YOU WILL INFRINGE.
You should be on the QNH of the airport concerned or a nearby one to ensure you remain outside CAS. Personally I only use RPS if there is nothing else available - which is very rare.
Last edited by Chilli Monster; 20th September 2007 at 21:27.
Joined: Oct 1999
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From: Anywhere
Read what I said above - that's the definitive rule.
However - it depends what the base of CAS was above you as I said before (indeed - the base of CAS could have been below you and you might have been in it
)
However - it depends what the base of CAS was above you as I said before (indeed - the base of CAS could have been below you and you might have been in it
)
