Hi all

Firstly, thank you all - and Bob in particular - for some absolutely wonderful PPL resources. I've worked my way through Bob's RPL and PPL books and found them the most useful of all the texts I've tried (including Dyson-Holland and David Robson's BAK series). This forum has been addictive to browse; and the online exams are - well, just great. Thank you, team, for all the hard work that must've gone into them.

I'm working my way now through practice exams. So far, so good; but this may be the first of several queries when I can't figure out why I've got an answer wrong.

So, the question is one about a trip from Wagga (YSWG) to Canberra (YSCN) and on to Merimbula (YMER), and interpreting an ARFOR to find freezing level (it was question 15 in Bob Tait's online exam #1, but I'm not sure whether the questions are randomised or not.....). Relevant data (from ARFOR No 2 on p46 of the CASA Day-VFR Exam Workbook V3) are:

SURFACE TROUGH AT 0400Z: THROUGH YSWG/YMCO
1000 Z : YCWR/YMRY
1600 Z : EAST OF AREA

SUBDIVISIONS:
A: E OF TROUGH
B: W OF TROUGH

AMD FREEZING LEVEL
A: 12000
B: 9500

The question asks "Freezing level forecast for your departure from YSWG (at 0500Z) is -"?

So, it appears to me that at 0500Z the trough will still be pretty close to the line YSWG/YMCO; pretty much the whole of Area 21, including all of our route, is east of this line, so in subdivision A of the ARFOR. So I selected '12000' as my answer. This was rejected, with the comment "For this trip, you need to plot the location of the trough on the PCA. For the Wagga - Canberra portion of the trip you will be west of the trough, therefore the freezing level from the ARFOR will be 9500 feet. Also remember you need to check the subdivisions - for this question you need to see subdivision B. The correct answer is: 9500"

So, what have I done wrong? Am I looking at the wrong data? Or will the trough really have moved that far in one hour (given that it will take six hours to reach the Cowra/Moruya line)?

Austin,

It's great to hear that you have found our resources helpful. Concerning the question on interpreting the ARFOR, the trough (it's obviously a cold front) is forecast to be located over YSWG at 0400 and your departure is at 0500. The question asks for the FZL at YSWG on your departure "Freezing level forecast for your departure from YSWG (at 0500Z) is -" At the time of your departure, the front will have passed YSWG and you will be west of the trough at that time.

Regards

Bob

Wow - thanks for the speedy reply.

Hmm - OK, that makes sense. So all they're interested in is the actual point of departure, not the actual trip to Canberra (most of which still lies east of the line)?

Bob, may I check another question with you - this time from the PPL Study Guide? I was considering making a separate thread for it, but the answer may be trivial, so let me check with you first.

Questions 125 and 126 start "Bob Tait's PPL Page 69 With reference to the chart on page 2.1.12 of Bob Tait's PPL....", with questions relating to (125) the wind direction at Melbourne, and (126) conditions expected at YPPH (Perth). The chart on p69 is the one attached here, numbered Fig 2.8 - I can't find either a page number or a figure number 2.1.12. It appears to show north-westerly winds over Melbourne, and a high over Perth suggesting hot conditions with northwesterly winds; however, the answers indicated as correct are south-westerly wind for Melbourne, and hot with easterly wind for Perth.



Have I simply got the wrong chart? I wondered if this was a 'hangover' from a previous edition, but this edition is 'Issue 1'. Or have I got completely the wrong idea about wind directions over pressure systems (clockwise round a low, anti-clockwise round a high)?

It is the incorrect figure. The figure in the current book is on page 72 and is called Fig 2.13. It has been changed in the current print of the book.



Bob

Lovely - thank you!

(I'm amazed by the speed of your responses - do you live online? I hope you get time off for flying that Decathlon once in a while..... But I'm certainly grateful!)

I'm not always that fast Austin. I just happen to be home with access to the office computer to-day. Too scary to be out of the house on Christmas eve in Brisbane!