PPL Met Question

[skipzoid]

Appologies if this isnt the right area, not very experianced in this forum type thing.

I recently took and sadly failed my Met exam.

My instructor just said I needed to re-read the book and didnt go through my failures instead said he wasnt allowed - seems a little harsh as I dont know my areas of weakness but hey - One question I remember having and have been unable to come up with a answer and dont know if I got it right or wrong was one that seems to have been asked before but not received an explaination to is -

I'm trying to recall this from memory, but the question goes something like - (I'm sure if you had the question or you're an examiner you'll know it exactly)

The moon is setting in the west, what direction has the best visability.
A)North
B)South
C)West
D)All directions are equal visibility.

I think I answered C - I think my reasoning was that is where the direction where the light was failing?

I cant find anything in my book about moonlight, perhaps someone could answer the question and explain why please? thanks.

I'm sure some of the questions are designed to spend one of the five wrong answers allowed. :)

[vw_nutter]

Hi
Sorry to hear about your exam. Just keep trying! Do you have the PPL confuser? Its worth getting if not. I also used AirQuiz online which was also a very good source for revision. I had the same question in my met exam. Remember that visibility does not improve as such, it only changes 'visibility range'. Flying with the sun behind improves visibility range, and flying towards the moon improves visibility range. The reason vis range improves when flying towards the moon is due to the silhouette of objects. I think the question you answered although probably phrased slightly differently is correct.
I would re-read your met book again and try some more practice questions either using PPL confuser or AirQuiz. I managed to get an average of 96% in my exams using a combination of the above and I also wrote all of the questions from PPL confuser in a note book and made side notes. If I wasn't sure about the answer I highlighted it and re-revised. My own technique which I have always used for exams and it hasn't let me down yet!
Good luck

[mattycourt]

Hi,

I too had this exact same question and did not have a clue what the answer should be as I do not ever recall studying it from the AFE Met. book.
However, I think I put C also but I can not remember if this was the correct answer or not from my paper.
I thought my exam went shockingly however I managed to pass with 75%. Not a great mark but a pass is a pass!
Good luck with your next re-sit!.

Regards

[24Carrot]

You have my sympathy, because I believe the correct answer is East!

I don't think there is any difference between sunlight and moonlight, so I will just talk about the sun.

If you have impurities in the air, (eg dust or water droplets), and they are the same size or bigger than the wavelength of light, you get Mie scattering of sunlight.

Without getting too much into Mie scattering, an important feature is that a small deviation from the light's forward course is more common than a sideways deflection, and backwards deflection is rare.

The consequence of that is when you look up-sun, a large part of the air between you and the ground is scattering light at you. A lot of the ground features will have lower illumination than this scattered light, and you will not see them.

Although moonlight is weaker than sunlight, the scattered light is decreased pro rata with the light reflected off what you are looking for, so that makes no difference unless it is lit.

The more you look away from the sun, the less light is scattered back at you, and so visibility is reduced less. Looking away from the sun (or moon) is best.

In real life it is more complicated because it depends on what you are looking for. For example a lake can be easier to spot up-sun, but not an aircraft. Also many things are lit at night.

But if the exam question is as you stated, I would go for west. I would discard North and South as they are equally right and wrong, and all directions because it is silly.

Finally, after every PPL exam I took (FW and RW, ie at two different schools) an instructor went through each wrong answer with me. I thought they were supposed to.

[IO540]

didnt go through my failures instead said he wasnt allowed

They do that to limit the number of exam questions which become public knowledge.

A stupid policy.

I think the answer must be East too, for same reason as 24C (that reads like a bra size) but there are so many other factors (like, bad visibility in a particular direction :) :) :) ) that this question is totally pointless.

[rsuggitt]

TBH, I'm not sure that anyone has the right answer yet. As a starting point, you have to ask what is the meteorological definition of visibility.

[OldBadger]

Hi skipzoid,

I am in a similar position training wise although have not yet attempted the met exam. I am at the moment reading the materials (AFE Set). Like you I saw no reference in the book to this question however in the AFE Q&A simplifier (example paper 2 - met) there is indeed a question very similar to the one you pose.

The answer they give as correct is flying towards the moon will give the best visibility.

"
although the debate is mostly subjective, rather than scientifically measured, many experienced pilots believe that at night, visibility is best when looking directly towards the moon than in any other direction.
"

I am not qualified to question this answer myself but it is what is given as the correct answer within the Q&A simplifier.

PS That book is well worth getting.

Hope that helps and good luck.

OldBadger

[IO540]

On that basis, the visibility would always be 149,597,870.7km (http://en.wikipedia.org/wiki/Astronomical_unit) during daytime :)

384,400 km (http://www.freemars.org/jeff/planets/Luna/Luna.htm) during the night, if the moon is visible :)

[vw_nutter]

24Carrot and rsuggitt - you need to check your books again! The answer I provided is correct. There IS a difference flying towards the sun and the moon and vice versa and they do NOT have the same effect on vis "range". Flying TOWARDS the moon improves visibility range. Flying AWAY from the sun improves visibility range. Simples :cool:

Met was the only exam I managed to get 100% on and I answered according to the above!

[Maoraigh1]

"384,400 km (http://www.freemars.org/jeff/planets/Luna/Luna.htm) during the night, if the moon is visible"
The most distant visible star islikely to be farther than that.

[IO540]

10/10 for lateral thinking but we would both fail the stupid CAA exam :)

[skipzoid]

Thank you to all for your valuble input, I didnt expect to start a mass debate :O

I assumed it better to fly in any other direction than where the sun is becuase of the dazzle factor, espcially when its low in the sky, but since night flight under VFR is prohibited I firstly didnt see the point of the question and secondly would never be able to make use of the knowledge anyway.

I still maintian its one of the questions designed to confuse and reduce the pass mark.

[MrAverage]

24Carrot

It is my understanding that the instructor that discussed detailed answer info with you was acting outside his privileges (he should not even have access to the answers unless he is also a ground examiner or flight examiner). If he is an examiner his instructions are quite specific - whether the student has passed or failed he must not discuss questions or reveal answers in anyway. He is only allowed to advise general areas that require revision. There are bona fide reasons for this policy.

[FALCONS CRUTCH]

Someone mentioned - Visibiliy - You can see the Galaxy Andromeda with the naked eye on a clear night, - thats just a mere - 2.2 million light years away ! One light year is - 6,000,000,000,000. miles . If we were flying at 100,000 mph. - it would take about 68 years just to cover
- 1 light year. So how do you define visibility. ?
The CAA. do ask very ambiguous questions. I was asked in one exam How many amps does it take to start a Garrett gas turbine? - no mention of the outside temprature, - it could have been minus 15 degrees

[IO540]

There are bona fide reasons for this policy.

Wot, like propping up the CAA policy of generating highly ambiguous exam questions and preventing this policy to be undermined by a public discussion?

The entire reason that instructors are not supposed to discuss actual questions is to prevent the reconstruction of the PPL question bank, which leads to effective revision aids like the PPL Confuser.

The funny thing is that ATPL cadets (hey, you have two ex cadets in the front of the 747 you fly on your next holiday ;) ) have the question bank in its entirety.

:ugh: :ugh:

[24Carrot]

Mr Average,

My language was sloppy.

For the most recent exams at least, it was indeed the examiner who went through the wrong answers. I don't recall the first set of exams so well, but it could have been the examiner in all those cases too.

I also dimly remember, now, being told back then that they only reviewed wrong answers if you passed the exam.

However, I don't know the examiners' rules, so I can't add anything more.

Later edit:
Having just checked Standards doc 11, para 2.9, it would seem Mr Average is right, and my several examiners were wrong.