PPRuNe Forums Help with altimeter question for air law exam

 Private Flying LAA/BMAA/BGA/BPA The sheer pleasure of flight.

 5th Jun 2012, 23:11 #1 (permalink) Join Date: Jul 2009 Location: Scotland Age: 28 Posts: 3 Help with altimeter question for air law exam Hi, I was not sure where i should post this question. I am just about to do my air law exam. I have been working through some example questions and i am not sure how to work out the following and need a bit of help: A pilot setting off on a cross country route in a cruise climb over a part of the country where the transition altitude is 3000 feet, has just been given a regional pressure setting of 970mb(hPa), from a local ATSU. His magnetic track is 260deg. What will be the transition level and what will be the lowest availabe flight level that the pilot can use, in accordance with the quadrantal rule? (assume that pressure falls with increasing height by 1mb every 30 feet). a. FL45 FL60 b. FL40 FL55 c. FL30 FL30 d. FL45 FL55 Thanks for any help. Regards, Ross
 6th Jun 2012, 00:54 #2 (permalink) Join Date: May 2005 Location: Aberdeen, UK Posts: 507 His magnetic track is 260, so an appropriate level for the quadrantal rule would be an Even flight level (0-90 Odd, 90-180 Odd +500, 180-270 Even, 270-000 Even +500). (just from the above, you already know the answer is (a) as it's the only even FL) So we can try FL40. FL40 is with 1013 set on the altimeter. But we have 970. That's 43 hPa below 1013, so FL40 is really 4000 - (43 * 30) = 4000 - 1290 = 2710 ft. 2710ft is below 3000ft, so we can't use that. As it has to be an Even FL, the next available FL is FL60. As a sanity check, 6000 - 1290 = 4710ft. So that one is fine. So it's (a). (I hope!) Last edited by Slopey; 6th Jun 2012 at 00:56.
 6th Jun 2012, 15:17 #4 (permalink) Join Date: Dec 2011 Location: euroga.org Posts: 2,468 Yes, the UK quad rule is bonkers (nobody else in Europe uses it) and the regional altimeter setting is also bonkers (nobody else in the world uses it). Also almost nobody flies the quad altitudes/levels in UK Class G. Flying them would merely increase the chance of hitting somebody because all traffic would be concentrated into altitude bands as potentially narrow as one's altimeter errors. Consequently, the ability to work out that answer is of no relevance to flying for real.
6th Jun 2012, 17:14   #5 (permalink)

Join Date: Aug 2005
Location: EGSX
Age: 45
Posts: 149
Quote:
 It did occur that the OP might be a troll, but if not I can sure understand the frustration
There are some odd posts on this forum. This person posted on 5th Dec 2009 that he was off to complete his PPL in California the next year, and then posted end Nov 2011 that he'd just started his PPL.

6th Jun 2012, 17:48   #6 (permalink)

Join Date: Jul 2010
Location: Near EBGB
Posts: 1,100
Quote:
 the regional altimeter setting is also bonkers (nobody else in the world uses it)
Whenever I call Brussels Information they are quick to give me the regional QNH.
I must admit I have questioned the usefulness of this parameter: more than once, upon returning from nav, I have found myself a hundred or more feet separated from people working t&g's in the circuit, still relying on local qnh as set before take-off.

 6th Jun 2012, 18:21 #7 (permalink) Join Date: May 2005 Location: Aberdeen, UK Posts: 507 Likely a troll, but I needed the practice - just off to do the IMC exam, and it loves those kind of things []
6th Jun 2012, 18:39   #8 (permalink)

Avoid imitations

Join Date: Nov 2000
Location: Wandering in hyperspace and the FIR
Posts: 8,041
Quote:
 I must admit I have questioned the usefulness of this parameter: more than once, upon returning from nav, I have found myself a hundred or more feet separated from people working t&g's in the circuit, still relying on local qnh as set before take-off.
The RPS is intended to safely separate you from the ground, not from other aircraft operating on a local, more accurate setting.

Obviously, it's a forecast lowest setting for a region, so it can hardly be expected to be accurate at any one airfield!

It dates back to a time when local altimeter settings were more difficult to obtain, especially for military aircraft flying at low level where radio contact was difficult or impossible.

I understand that in UK it will cease to be used in the fairly near future.

6th Jun 2012, 19:45   #9 (permalink)

Join Date: Mar 2010
Location: Up North
Age: 46
Posts: 481
I think that the ASR/RPS situation will be changing, rather than them disappearing all together, from the consultation document;
http://www.caa.co.uk/docs/2257/20120...onDocument.pdf
Quote:
 49. It is accepted that the map of the UK Altimeter Setting Regions (ASRs) is likely to change as a consequence of the change to the TA. Extensive work has already been undertaken by the TAPT and the UK Met Office to determine the issues associated with revising the ASRs. This work will continue during the initial consultation period to ensure that the eventual shape of the new ASRs balances the needs of all airspace users to the greatest extent possible. Once complete, findings will be distributed to stakeholders for comment.

 6th Jun 2012, 20:00 #10 (permalink) Join Date: Mar 2010 Location: Up North Age: 46 Posts: 481 Hi Slopey, If you're about to take the IMCr theory exam, be careful where the quadrantals change. They're actually; 000 - 089 ODD 090 - 179 ODD+500 180 - 269 EVEN 270 - 359 EVEN+500 Small difference I know, irrelevant in practice, but might make the difference in a theory exam, if whoever wrote the questions put the magnetic track right on the edge of the quadrant.
 6th Jun 2012, 20:07 #11 (permalink) Avoid imitations   Join Date: Nov 2000 Location: Wandering in hyperspace and the FIR Posts: 8,041 I say again, the proposal is for the cessation of use of the term "Regional Pressure Setting (RPS)" As that document states, there are some disadvantages in doing away with RPS. Not surprisingly the same reasons why it was first introduced. Time will tell once the consultation process is completed.
6th Jun 2012, 21:11   #12 (permalink)

Join Date: Aug 2002
Location: United Kingdom
Posts: 1,960
peter337 said
Quote:
 and the regional altimeter setting is also bonkers (nobody else in the world uses it).
Jan Olieslagers said
Quote:
 Whenever I call Brussels Information they are quick to give me the regional QNH.
Shome mishtake, shurely?

6th Jun 2012, 21:41   #13 (permalink)

I'd rather be floating

Join Date: Nov 2000
Location: Cambridge, England
Posts: 2,538
Quote:
 if whoever wrote the questions put the magnetic track right on the edge of the quadrant
Do they ever not??

And for a bonus they try to do so such that if you erroneously use true track instead of magnetic you end up with the wrong level.

 6th Jun 2012, 23:25 #14 (permalink) Join Date: May 2005 Location: Aberdeen, UK Posts: 507 @mrmum - yep, brushed up on that while waiting for the exam - sneaky quadrantal rule maker-uppers! Anyway 92%, very happy
 7th Jun 2012, 06:16 #15 (permalink) Join Date: May 2001 Location: Aberdeen,Scotland,UK Posts: 8,194 I thought the quad rule was a thing of the past now with EASA?
 7th Jun 2012, 08:44 #16 (permalink) Join Date: Aug 2002 Location: United Kingdom Posts: 1,960 Not yet, Jock, you'll have to wait for Part-SERA before you see the end of Quadrantals.
7th Jun 2012, 09:23   #17 (permalink)

Join Date: Feb 2007
Location: Amsterdam
Posts: 4,201
Quote:
 I understand that in UK it will cease to be used in the fairly near future.
I wonder what's going to replace it then, especially as they're going to raise the TA to some very high level, which would mean that more, not less, aircraft will need to fly on some sort of RPS.

The UK is NOT the only country using RPSs. It is, as far as I know, the only country that gave them funny names ("Skua QNH ..."), while other countries use names that have more meaning without detailed geographical knowledge ("North Sea North QNH ...").

Anyway, the way a FIR is divided up into RPS regions is listed in AIP ENR 1.7. The Netherlands has four (North Sea North, North Sea South, Amsterdam, Maastricht). Belgium has only one, which is called "The regional QNH". The UK has 20 regions, France has 5 FIRs with three to five QNH reporting stations in each, and so forth. So the concept of RPSs is universal.

 7th Jun 2012, 11:34 #18 (permalink) Avoid imitations   Join Date: Nov 2000 Location: Wandering in hyperspace and the FIR Posts: 8,041 Backpacker, the document link given by mrmum gives details of the CAA proposals. Looks like it will probably be brought in line with the system used in Europe....i.e. similar system to the present (or worse?), just given a name change to make us more European. Obviously, the way to improve the service by making it more accurate would be to provide a better network of local, real time, met broadcasting stations but unfortunately that would cost money and is probably unlikely to happen.
 7th Jun 2012, 14:02 #19 (permalink) Join Date: Sep 2011 Location: Mare Imbrium Posts: 170 Archaic indeed; but then I've never used them or known anyone that has. H
7th Jun 2012, 18:03   #20 (permalink)

Join Date: Oct 2001
Location: Essex
Posts: 347
Quote:
 Also almost nobody flies the quad altitudes/levels in UK Class G
Get up higher and you will find that lots do!

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are Off Refbacks are Off Forum Rules

All times are GMT. The time now is 15:37.