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# ATPL theory questions

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# ATPL theory questions

13th Jul 2017, 06:49

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Originally Posted by fly5N
Hello, I came across a difficult PSR/PNR question while writing SACAA IR Exams and I need your help. Twice infact and all were similar.

I was given a PET Distance of I think 1200nm and distance from point A- B of 2300 NM if I remember correctly. Total fuel was about 15000kg and that was all. No speeds or endurance was given or wind. I was then asked to calculate PSR from point A to B.
Hello maybe I can contribute to the question because I had a similar one,

I got during my IR rating exam an interesting PSR\PNR question where I am going right now crazy to get to a solution. I asked now already everyone at flight schools, looked in different forums, but could not find an answer. I even asked already the authority, but they were not authorized to help me...

Hopefully you guys can help me here with a solution.

The question simple:
- distance A to B 2000NM
- TAS, wind, endurance constant
- 5000kg fuel (+500kg extra)
- PET from A 1200NM

what is the PNR\PSR?

answeres: I cant remember the values any more but for the approach process it should be not an issue. There were 5 answeres and I chose c.) which was 1200NM (same as PET and which is wrong).

My approach was the following, due to the fact that there are to less variables for calculations, no given fuel flow,..., it's more a theoretical question. TAS, wind, endurance are constant, so I thought it might be one of the rare cases where PET=PSR, which leads me to another question:
- Can PSR be equal PET and\or is PSR always more\less then PET?

I assume that when there is no wind and PET is exactly half of the distance, is there also PSR half of the distance or more\less?

In the example above I know I have headwind doe to the fact that PET is closer to B, so if PSR is maybe always more then PET then there might was only one answer which was more then 1200nm...

Or maybe I am completely wrong...,
anyways, appreciate your help in this case!
13th Jul 2017, 06:58

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And maybe another question which is right now a little bit a pain in my ass, where even after discussion with mechanics I came to no solution.

Which TWO instruments are adversely affected by an electrical power failure in flight?:
A. ASI
B. Magn. compass
C. DI
D. AI
E. CDI

A and b definitely not. I would have chosen c,d,e but the question said TWO, and now i am strungling. The discussion with the mechanics ended up that it's c and d, but also a cdi could be affected depending on an old or new one...

So hopefully someone here knows the right answer and can explain why.

Appreciate it, thx
13th Jul 2017, 12:19

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The compass is swung with all the electrics on, so if they fail, the deviation card will be inaccurate.
14th Jul 2017, 07:36

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Thx for this true statement, unfortunately helps not for the answer to the question.
14th Jul 2017, 12:39

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IIRC, An AI can be either air driven or electrically driven so therefore is not entirely susceptible to a power failure. Is that the possible reasoning ?
15th Jul 2017, 22:54

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Starboard or Port drift?

Probably a super stupid question but how do you know if it's starboard or port drift? When you are calculating headings on the CRP 5 (chapter 8 Oxford ATPL navigation). Example: the heading is 060 and the track is 065 which means you have 5 degrees starboard drift. I understand how they got the 5 and all that. But how do I know if it's port or starboard? Any rules of thumb?
16th Jul 2017, 06:29

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Port & Starboard

There is no such thing as a stupid question Sonbre! Unless it's "what colour is the green navigation light"?

Anyway assuming you are using wind-down method (one reason it's used is it shows drift in the correct sense). Your heading will be at the top and your pencil dot will be usually be on the left or right hand side of the CRP5 centre line.

In your example heading of 060 is at the top and the pencil dot will be on the 5 degree right drift line. If it's on the right then this is starboard drift, if your pencil dot is on the left then this is port drift. Remember that wind ALWAYS blows from heading to track.

These phrases like several aviation ones date back to the days of sail, (like some of the dire questions) in the EASA exams they are more likely to use the phrases left or right drift.
16th Jul 2017, 16:56

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Port means your left side and starboard means your right side. So in the example you have given, you are looking along your 060 heading, but actually moving in the direction 065. This means that you are drifting 5 degrees to your right (starboard) side.
17th Jul 2017, 11:10

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Originally Posted by WASALOADIE
IIRC, An AI can be either air driven or electrically driven so therefore is not entirely susceptible to a power failure. Is that the possible reasoning ?
Which means the correct answeres would be the cdi and the di...but also not 100%sure.
I love it when the authorities give you not enough infos for solving a question.
18th Jul 2017, 20:02

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You have to love the examiners' simplicity, not specifying the type of aircraft. Or maybe they did and its not included in the feedback?

Which TWO instruments are adversely affected by an electrical power failure in flight?:
A. ASI
B. Magn. compass
C. DI
D. AI
E. CDI
On an aircraft like the older 747s with servo driven main instruments the answer is "all" but one has to assume something so I will assume they are talking about a light aircraft. On such an aircraft:
• the ASI has no power supply, it is not affected
• the direct reading magnetic compass has no power supply, but its reading is affected because the deviation correction is done with all power supplied, and therefore it may be incorrect if the electrical power fails. If the compass is remote reading it will require power and therefore be affected.
• the DI is air driven
• the AI is air driven
• the CDI (if it has one) is powered

and therefore I would go for B and E.
19th Jul 2017, 09:15

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Thx for the feedback. No, the question is like its mentioned. There is nowhere an a\c type or heavy\light a\c,...

And you are right, found also some interesting stuff in inet:

With this in mind, the correct answers are:
Magnetic compass and CDI

And I was always so sure that the magn. Compass is definitely affected but that much that it could be adversely affected (only a few degrees but still working), but I think this is the reason why the authorities use these words. Only to trick you around and make you doubting your thoughts, even when they are right.

Last edited by Rusty1983; 22nd Jul 2017 at 08:59. Reason: I was wrong
2nd Aug 2017, 17:18

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Can someone be so kind as to explain briefly the working principle behind spring tabs?

Also, would I be correct in saying that we have

External/Control Balance Tabs

- basic elevator tabs (controlled by a wheel/flick switch),
- Balance/Anti Balance tabs (not moved by pilot ... move with control surface)
- servo tabs
- spring tabs

Internal Balance Tabs

- control horns
- insert hinges

The above being all that is necessary for the ATPL (POF) ... this shouldn't be a difficult topic but it's something I'm slower to get to grips with than others. I have used the BGS ATP extensively but unfortunately some things are still not clear for me. Any help is appreciated
7th Aug 2017, 00:47

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Need a minimum of 4 satellites for a 3d fix from GPS.
Latitude, Longitude, Altitude and Time all need to be determined.
12th Aug 2017, 16:21

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Hi,

can anyone help with this question please? :-)

An aircraft follows a true course of 140°(T) for 1 hour 42 minutes between 45°N 070°W and 42°N 062°W. Calculate how much drift (and in what sense) will be observed on an uncorrected DGI.

Solution -24°
13th Aug 2017, 15:11

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The drift is the heading error.
It is due to two things :
- earth rotation
- moving along a parallel of latitude
You've got here :
1.7h * 15°/h = 25.5°
8° of longitude variation
Multiply that by sin(meanlat) which is about 0.7
You'll find something very close to -24°

Just take a few minutes to imagine the situation and confirm that both signs are negative.
17th Aug 2017, 19:29

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Can anyone help me with this?

The book says: Calculate the airspeed in knots for each highlighted coefficient of lift.
I don't need the answer for a specific number I just want to know how to do it. What formula to use and so on.
Thanks;-)
18th Aug 2017, 11:16

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Sonbra,

You have not provided many clues, but I suspect that the equation you require is the lift equation.

Lift equals Cl 1/2Rho Vsquared S.

If we keep Rho and S constant then to maintain constant lift for any changes in Cl we need an equal and opposite change in V Squared.

So for example if we half Cl from say 0.5 to 0.25, then we must double V squared. To achieve this we would multiply V by the square root of 2.
18th Aug 2017, 13:51

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Thanks! I do understand the formula. But I don't get the right answer!
The CL is 0.384, the Newton of lift is 588600N (60000X 9.81) the wing area is 105 and the density is 1.225 kg/m3

The answer supposed to be 300knots. But how?
18th Aug 2017, 18:57

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You must ensure that you use consistent units throughout the calculation. You have Newton, and metres, so you need to convert your 300 knots into metres per second. Hopefully your books have stated what conversion factor to use, but if not you should try using 0.514 m/S per knot, which is a reasonable approximation.

Last edited by keith williams; 18th Aug 2017 at 19:12.
11th Sep 2017, 09:40

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Originally Posted by Rusty1983
Hello maybe I can contribute to the question because I had a similar one,

I got during my IR rating exam an interesting PSR\PNR question where I am going right now crazy to get to a solution. I asked now already everyone at flight schools, looked in different forums, but could not find an answer. I even asked already the authority, but they were not authorized to help me...

Hopefully you guys can help me here with a solution.

The question simple:
- distance A to B 2000NM
- TAS, wind, endurance constant
- 5000kg fuel (+500kg extra)
- PET from A 1200NM

what is the PNR\PSR?

answeres: I cant remember the values any more but for the approach process it should be not an issue. There were 5 answeres and I chose c.) which was 1200NM (same as PET and which is wrong).

My approach was the following, due to the fact that there are to less variables for calculations, no given fuel flow,..., it's more a theoretical question. TAS, wind, endurance are constant, so I thought it might be one of the rare cases where PET=PSR, which leads me to another question:
- Can PSR be equal PET and\or is PSR always more\less then PET?

I assume that when there is no wind and PET is exactly half of the distance, is there also PSR half of the distance or more\less?

In the example above I know I have headwind doe to the fact that PET is closer to B, so if PSR is maybe always more then PET then there might was only one answer which was more then 1200nm...

Or maybe I am completely wrong...,
anyways, appreciate your help in this case!

Hello,
Unfortunately I got no response on the question above, but maybe someone have a clue of a new one that I got at my last exam.

Even this one I was not able to figure out or find any solution hints in the internet. I really like to meet these Sadists who create such questions!

Dist. A - B = 1200Nm
PSR is 84% of AB
PET is 60% of AB
Endurance = 8h24mins

What is the Groundspeed from PSR to A?

I am going already crazy with these questions...everyone I ask, no one has a clue