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Regional QNH or 1013
Hi there, could anyone advise me on this one, planning a couple of flights above the transition level circa 5000 ft or FL 50, in uncontrolled airspace, and for terrain clearance I`m not sure what altimeter setting to use as were not planning to fly the quadrantal rules, the flights will be conducted VFR, asked some flight instructors and pilots with many more hours than me and the results are equal, also in the Trevor Thom manuals it states that if you have various headings use regional QNH, so any advice would be much appreciated thanks in advance.
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just watchout for the base of CAS it could be altitude or FL.:ok:
At 5000' I doubt you'll hit any terra firma |
Above transition level (certainly above FL50 in the UK), I'd use QNE (1013) for traffic avoidance. Below TL, I'd use RPS (regional pressure setting, commonly but slightly incorrectly called regional QNH) for terrain avoidance.
And talk to ATC and make sure they know what setting you're using. G |
Is this a troll?
Above the transition layer you use 1013, below it you use the RPS for FL/altitude reporting. Simple really. The only variable is the altitude of the TL itself. And the RPS of course. The quadrantal rule (or semi-circular rule) is formulated so that it uses altitudes (thus based on the RPS) below the TL, and uses FLs (thus based on 1013) above. Same goes for the vertical limitations of CAS. At 5000' I doubt you'll hit any terra firma |
You don't have to use FL if VFR but I always do because most of the class A airspace (airways etc.) are normally a FL so it ensures you won't bust them. I'd always plan to try and fly at FL50 or above on a reasonably long x/c because you have less traffic to worry about up there and comms / radar are better. I'd always aim to fly a quadrantal level but sometimes that isn't possible due to the weird class A airways in the UK.
The TA is normally choses at an alt above the highest terrain around, so in the USA is is 18,000. IN the UK not much extends above 3000', though I reckon it would be sensible for Europe to have one common TA which is based upon the highest of the Alps. |
You don't have to use FL if VFR But as far as I know you have to use flight levels in your reporting to ATC, if you're above the TL. I mean, you don't want to leave the mental arithmatic to the controller, do you? "G-ABCD report altitude" "6200 feet QNH 1003 G-CD" "G-DEFG report altitude" "FL65 G-FG" Now is there a conflict or not? (And what's more important: How many seconds did it take you before you found the answer?) |
Worth mentioning that most pilots don't actually care about any of the above, with the main objective being to keep out of controlled airspace ;)
So if flying below CAS whose base is defined as a flight level, you fly on 1013. If flying below CAS whose base is defined as altitude, you fly on the actual QNH, but that gets a little tricky because the regional pressure setting is no good for staying below CAS. The "proper way" to stay below CAS whose base is defined as an altitude is to obtain the QNH from the ATC unit responsible for that piece of CAS (which you can do by calling it up, or by dialling up its ATIS). |
Or you do as I do when doing aerobatics between 3000' (below the TA) and FL 55 (above the TL): Leave the altimeter on QNH and use the transponder to see what FL you're at (has to be a mode C or S, obviously).
(My usual aerobatics location has several layers of CAS so I run the risk of busting both below and above.) |
Personally I find regional QNH to be fairly useless. If you don't want to use 1013 - and I don't bother if I'm just farting around aka enjoying flying - then I would recommend using the QNH of any airfield near your track (within 25nm if you want to be correct), and I would further recommend using ATIS broadcasts to get them as you don't have to bother making R/T calls then.
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If you're squawking 7000 Mode C (as you do, don't you?) your altitude on the radar controller's screen will be based on FL/1013, so it makes eminent good sense if you're above TL whether you're farting about or not to use FL /1013 on your altimeter.
Cusco |
BackPacker wrote: But as far as I know you have to use flight levels in your reporting to ATC, if you're above the TL. I mean, you don't want to leave the mental arithmatic to the controller, do you? "G-ABCD report altitude" "6200 feet QNH 1003 G-CD" "G-DEFG report altitude" "FL65 G-FG" Now is there a conflict or not? |
DB6 wrote: Personally I find regional QNH to be fairly useless. If you don't want to use 1013 - and I don't bother if I'm just farting around aka enjoying flying - then I would recommend using the QNH of any airfield near your track (within 25nm if you want to be correct), and I would further recommend using ATIS broadcasts to get them as you don't have to bother making R/T calls then. |
I'm searching for an example where there is terrain that extends through the TA into the Flight Levels, and which would make a re-calculation of that terrain altitude to its corresponding FL necessary to stay safe. Does anyone know of such an example? |
The airport I work (UK) at has a transition altitude of 3000' and an MSA of 3200' in one sector - is that what you mean?
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Originally Posted by Genghis the Engineer
Above transition level (certainly above FL50 in the UK), I'd use QNE (1013) for traffic avoidance. Below TL, I'd use RPS (regional pressure setting, commonly but slightly incorrectly called regional QNH) for terrain avoidance.
QNE is not a pressure setting. QNE is the reading in feet on an altimeter with the sub-scale set to 1013.2 mb when the aircraft is at aerodrome or touchdown elevation. During conditions of exceptionally low atmospheric pressure it is not possible to set QFE or QNH on some aircraft altimeters. In these circumstances an aerodrome or runway QNE can be requested. 1013.2 is the Standard Pressure Setting. Flight Levels are measured with reference to the standard pressure setting of 1013.2 mb. In the UK, consecutive Flight Levels above the transition level are separated by pressure intervals corresponding to 500 ft; at and above FL200, by pressure intervals corresponding to 1000 ft. The Regional Pressure Setting is a forecast of the lowest QNH value within an ASR. The values which are made available hourly for the period H + 1 to H + 2, are given in whole millibars. UK Altimeter Setting Procedures are here.
Originally Posted by Cusco
If you're squawking 7000 Mode C (as you do, don't you?) your altitude on the radar controller's screen will be based on FL/1013, so it makes eminent good sense if you're above TL whether you're farting about or not to use FL /1013 on your altimeter.
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UK terrain above TA/TL
I'm searching for an example where there is terrain that extends through the TA into the Flight Levels, and which would make a re-calculation of that terrain altitude to its corresponding FL necessary to stay safe. Does anyone know of such an example? Plenty around the world. None in the UK AFAIK. |
in UK airspace the transition altitude outside CAS is 3000' |
Originally Posted by soaringhigh650
What if you're OCAS below a CAS shelf? Is it still 3000 feet?
Ref in UK AIP somewhere. |
TA outside CAS
Originally Posted by soaringhigh650 What if you're OCAS below a CAS shelf? Is it still 3000 feet? UK AIP (11 Feb 10) ENR 1-7-1 Civil Aviation Authority AMDT 2/10 ENR 1.7 — ALTIMETER SETTING PROCEDURES 1 Notification 1.1 The Selected Transition Altitudes listed in paragraph 4 are notified for the purposes of Rule 34 of the Rules of the Air Regulations 2007. 3 General Procedures 3.1 The Transition Altitude within the UK is 3000 ft except in, or beneath, that Airspace specified at paragraph 4.1. 3.9 Airspace within all Control Zones (CTRs), and within and below all Terminal Control Areas (TMAs), Control Areas (CTAs) except Airways and the Daventry and Worthing Control Areas, during their notified hours of operation, do not form part of the ASR Regional Pressure Setting system. 3.10 When flying in Airspace below TMAs and CTAs detailed above, pilots should use the QNH of an adjacent aerodrome when flying below the Transition Altitude. It may be assumed that for aerodromes located beneath such Areas, the differences in the QNH values are insignificant. When flying beneath Airways whose base levels are expressed as Altitudes pilots are recommended to use the QNH of an adjacent aerodrome in order to avoid penetrating the base of Controlled Airspace. 4 Selected Transition Altitudes 4.1 The following Transition Altitudes apply to flights within or beneath the following Airspace: Aberdeen CTR/CTA 6000 ft Belfast CTR/TMA 6000 ft Birmingham CTR/CTA 4000 ft Bristol CTR/CTA 6000 ft Cardiff CTR/CTA 6000 ft Doncaster Sheffield CTR/CTA 5000 ft Durham Tees Valley CTR/CTA 6000 ft † East Midlands CTR/CTA 4000 ft Edinburgh CTR/CTA 6000 ft Glasgow CTR/CTA 6000 ft Leeds Bradford CTR/CTA 5000 ft † London TMA 6000 ft Manchester TMA 5000 ft Newcastle CTR/CTA 6000 ft Scottish TMA 6000 ft Solent CTA 6000 ft † Sumburgh CTR/CTA 6000 ft † † Note: Outside the notified hours of operation the Transition Altitude is 3000 ft. |
This is horribly complicated and potentially dangerous too. :uhoh:
There needs to be a common TA. |
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