ATPL Navigation questions

[The Hypnotoad]

I'm self studying above exam using AFT notes, which have proved very helpful, but when I come across LPSD questions I end up in a heap. Not because I don't understand the theory behind it (the way AFT say to go about it and plot lines all over your ERC is very simple) but the problem is I cannot get a distance measurement accurate enough. I'm just using a WAC scale ruler and then multiplying by 3 as one "WAC" mile seems to equal about three "ERC" miles.
I'm sure the answer I get would be sufficient enough for real world ops but in CASA theory exam land my answer will plonk me, 99% of the time, smack bang between the two "most correct" CASA answers. As an example the question I just completed had 260NM and 270NM as the "most correct" answers and my working got an answer of 264NM. So I picked 260NM and was wrong.:{:sad:
Is there a better way? Is there such a thing as an ERC ruler? I'm looking for the obvious but can't see it and I'm doing my head in :ugh::ugh:yet hundreds have been there before and found a way? Help would be great!:)

[alphacentauri]

Hypnotoad,

Mate all the ERC's are not the same scale. Your one "WAC" mile seems to equal about three "ERC" miles will not work across the board, if at all.

Because each ERC is at a different scale, each one has its own scalebar, printed normally at the bottom of the chart. You get a normal ruler (a 40cm one is a good start) and work out the distance from the ruler vs the scalebar.

Did my ATPL nav exam a few months ago, and this worked for me.

Cheers
Alpha

[JulieFlyGal]

I use a divider to measure distances on ERCs. So pick a line of longitude and measure it in the north-south direction. Each degree of latitude is 60 nautical miles. You'll find that they usually have markers every 10 minutes (10 miles) so use this as kind of scale as well. Dividers are allowed in the exam so I guess they want you to use it. (Note .. dividers are sometimes referred to as 'protractors' .. not sure which is correct.)

[boltz]

Use dividers to measure the distance. Then measure it against the scale provided on the bottom or side of the map.

[Enema Bandit's Dad]

Or when in doubt pick C. Works well :bored:

[Tinstaafl]

Likewise. Dividers. Simpler & more accurate than trying to use an incorrect scale ruler and correcting the reading. Particularly germaine considering you're having problems measuring distance accurately using the wrong scale with an approximate correction factor.

[PercyWhino]

With the ERC being a Lamberts conformal projection the scale is only accurate on the standard parallels.

Just completed my ANAV last week, used the dividers and used the lines of lattitude. 1 degree = 60nm, And that seemed to work well. My answers for the PSD and CP were very accurate.

[The Hypnotoad]

Thank you very much everyone. I had no idea what these dividers were previously. I see divider and think of the bits of plastic that separate papers in your ringbinder files.:\

[Tinstaafl]

It's a amazing how much easier & quicker problems are with the correct tools for the job. Good luck!

[FRQ Charlie Bravo]

Hi all,

just a bit of info. Despite the excellent advice from JulieFlyGal this is a protractor:
http://www.google.com.au/images?q=tbn:PWA4pUuaYAgvVM::www.dynapod.com/protractor2.jpg (http://www.google.com.au/imgres?imgurl=http://www.dynapod.com/protractor2.jpg&imgrefurl=http://www.knifesharpeningtips.com/how-to-angle-the-blade/&h=571&w=1112&sz=219&tbnid=PWA4pUuaYAgvVM:&tbnh=77&tbnw=150&prev=/images%3Fq%3Dprotractor&usg=__umSZpMM6x3Bwyh2wyyFuGOY5QS0=&ei=ofx9So70O8iZkQXUmJSIAw&sa=X&oi=image_result&resnum=1&ct=image).

A compass is what you may mean and that is essentially a set of dividers with a pencil holder like this bad boy :
http://tbn3.google.com/images?q=tbn:jJHzhW6qN4snNM:http://bp1.blogger.com/_3lVJHEFGQrA/Rl55VlP7VOI/AAAAAAAAAcQ/ZFAhf051M3w/s320/Compass%2BWith%2BRed%2BPencil.jpg (http://images.google.com.au/imgres?imgurl=http://bp1.blogger.com/_3lVJHEFGQrA/Rl55VlP7VOI/AAAAAAAAAcQ/ZFAhf051M3w/s320/Compass%2BWith%2BRed%2BPencil.jpg&imgrefurl=http://postcardfrompuniho.*************/2007_05_01_archive.html&usg=__U1Y9QJqoOR_NmKGDUPTLU83LKYg=&h=312&w=320&sz=19&hl=en&start=3&um=1&tbnid=jJHzhW6qN4snNM:&tbnh=115&tbnw=118&prev=/images%3Fq%3Dcompass%2Bwith%2Bpencil%26hl%3Den%26client%3Dfi refox-a%26rls%3Dorg.mozilla:en-GB:official%26sa%3DG%26um%3D1) (this $3 tool is what I suggest using as it's a bit more useful but have a set of true dividers in your bag in case your exam invigilator disagrees - very unlikely)

If you want to spend about $60, how about this ninja-like set of dividers (when I was in the military we called them "ten points"... despite having eleven points).

http://ec1.images-amazon.com/images/I/51v9g42vsmL._AA280_.jpg

Take a green Texta to seven points and a black Texta to the others then using any line of longitude (N-S) place the Zero point (the first of the green tips) on zero and the Six point (the seventh green point) 60 degrees or 60 nm away and you've got 10 nm miles per division.

Another use for these "ten points" is on the Perf and Loading exam (interpolating on perf charts) and the Flight Planning exam (Initial Buffet Boundry charts etc).

Bellow is a collection of inexpensive compasses (pencil or lead holders) and dividers.

http://www.theartistsdepot.com/images/Site_Ready/Thumbs/tn_jetbow_divider.jpg

~FRQ CB

PS I agree with Enema Bandits Dad, when in doubt Charlie out.

[JulieFlyGal]

A compass is what you may mean and that is essentially a set of dividers with a pencil holder like this bad boy :

Oh yes. That's what I meant. Dividers are some times called compasses. And agree compasses are probably more useful than dividers, provided you have a really sharp pencil.

[captaintunedog777]

And this guy is a future potential airline pilot. Oh my scary $hit. :\

[FRQ Charlie Bravo]

And this guy is a future potential airline pilot. Oh my scary $hit.Let's just see if I can use my ASIC to get my ten-points through security... in my shoe (James Bond, From Russia With Love):http://www.freewebs.com/scaramangasgoldengun/vil7.JPG