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# ATPL theory questions

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# ATPL theory questions

26th Jan 2017, 14:12

Join Date: Nov 2000
Location: White Waltham, Prestwick & Calgary
Age: 67
Posts: 3,750
the .32 was supposed to be the tan of 60, at least that's what the internet site I used said .

Multiply by the groundspeed and divide by 60 was the formula for TW.

G/S x tan lat
60

However, having used a real calculator this time , the tan lat is 1.73, so that ends up with 5.77 or 6 degrees for government work

As it is minus because you are going E, apply to the -13 for the apparent wander to get -19, subtract from 90 to get 81, answer B
26th Jan 2017, 14:49

Join Date: May 1999
Location: Bristol, England
Age: 60
Posts: 1,472
its a correction per hour, so you need to multiply 5.77 x 1.5 = 8.66. Same as the convergency, because its the convergency that causes TW.

I'm guessing you had put your calculator down by the time you said 90 - 19 = 81!
26th Jan 2017, 15:02

Join Date: Nov 2000
Location: White Waltham, Prestwick & Calgary
Age: 67
Posts: 3,750
Duh!!!!! Yep!

Not enough blood in the coffee stream.....

But sorted in the end!
26th Jan 2017, 18:09

Join Date: Dec 2015
Location: France
Posts: 434
So .. 71 and that is answer (a+c)/2 ?
26th Jan 2017, 20:17

Join Date: May 1999
Location: Bristol, England
Age: 60
Posts: 1,472
Well I think 079, but I'm open to comments
26th Jan 2017, 20:17

Join Date: Dec 2015
Location: France
Posts: 434
Just got that exact question in AvExam

Or.. if you're on a transoceanic flight you'll most probably have a computer able to that computation for you
26th Jan 2017, 20:21

Join Date: May 1999
Location: Bristol, England
Age: 60
Posts: 1,472
and what was their explanation?
26th Jan 2017, 20:37

Join Date: Dec 2015
Location: France
Posts: 434
How the are we supposed to guess if they're talking about wake turbulence category or approach category ?
https://i.gyazo.com/e06e9a296a75cb43...9046dbe357.png
26th Jan 2017, 20:39

Join Date: Dec 2015
Location: France
Posts: 434
It resembles the one I had however everybody will use some variation of that to get the right answer
https://i.gyazo.com/526f9f0281c28855...5c004ee547.png
26th Jan 2017, 21:01

Join Date: May 1999
Location: Bristol, England
Age: 60
Posts: 1,472
ah their earth rate is different to mine, 19 deg rather than 13 deg. I copied Paco for that figure - I'll check it.

.... not multiplied by 1.5...

earth rate is 19.5 deg, amended total drift is 19.5 + 8.7 = 28.2

and whether you apply it to the great circle or rhumb line tracks the average is 076. Agreed.

I really shouldn't attempt these calculations!
26th Jan 2017, 23:22

Join Date: Dec 2015
Location: France
Posts: 434
And now that I have finished comms, ops, air law and half of instruments questions on avexam, I do realise that it is actually possible to learn the answers to the questions.

I could not believe that one could remember thousands of pieces of data, but even I with a rather bad memory, the answers that can't be figured out by understanding and thinking can very well pop up in my mind because I just remember having seen them.

Which is a bit frightening.... as well as satisfactory because, you know, I have to pass my exams in a short time
27th Jan 2017, 05:50

Join Date: Nov 2000
Location: White Waltham, Prestwick & Calgary
Age: 67
Posts: 3,750
"I really shouldn't attempt these calculations!"

Neither should I Back to sleep....
27th Jan 2017, 08:50

Join Date: May 1999
Location: Bristol, England
Age: 60
Posts: 1,472
What is even more embarrassing is that the question has been in our database since 2011, and I didn't look.
27th Jan 2017, 09:34

Join Date: Nov 2000
Location: White Waltham, Prestwick & Calgary
Age: 67
Posts: 3,750
LOL!! I wonder if it is still in the real one? Maybe I will ask!
28th Jan 2017, 10:03

Join Date: Aug 2012
Location: Greece
Age: 38
Posts: 22
I need your help on the following questions-sentences.
Please,correct me if I am wrong!

1)The two points are on the same parallel of latitude (60o).The part of parallel of latitude that connects them is a rhumb line since it cross the meridian of 10 and 20 degrees of longitude at the same angle (which is 90 degrees).
Do you agree?

2)An aircraft that will fly from A to B (eastward direction),will have a constant TRUE TRACK of 90.

3)The gyro compass is aligned on the point A with TRUE north.So,when the trip starts the gyro compass shall indicate 090 (since there is no wind,right).But as the aircraft flies due to precession the indication of gyro compass is altered.
Do you agree?

4)In order to fly on a constast gyro track we have to alter the TRUE HEADING in the beginning of the trip by the half of the precessions?

28th Jan 2017, 10:36

Join Date: May 1999
Location: Bristol, England
Age: 60
Posts: 1,472
1) yes
2) No. A true (and complete) statement would be "An aircraft can follow the rhumb line track A to B, in which case its true track would be a constant 090 deg, but the path will be curved. It can also take the shortest straight line route, a great circle, in which case the intitial true track will be less than 090, its final true track greater. The aircraft could also take any number of curved tracks other than the rhumb line between A and B."
3) See above. This is correct assuming you try to follow a rhumb line path, but why would you?
4) Will think about this. It is probably true, but your true heading will represent neither the rhumb line nor great circle track. The aircraft will follow a curved path to the north of the great circle.
31st Jan 2017, 14:24

Join Date: Jan 2011
Location: England
Posts: 642
The aircraft will follow a curved path to the north of the great circle.
I do not believe that the above will always be the case.

At the Equator there will be no ER or TW, so you will flt along the Equator.

When going west in the northern hemisphere at a ground speed equal to the rotational speed of the Earth at that latitude, the TW will be equal and opposite to the ER, so there will be no wander. This means that you will fly along the parallel of latitude on a 270 true heading.

If you fly west at any higher ground speed the TW will be greater than the ER, so your track will be south of the Parallel of latitude.

I could be wrong of course.....this age-induced brain fade is a terribly sneaky creature!
31st Jan 2017, 21:18

Join Date: May 1999
Location: Bristol, England
Age: 60
Posts: 1,472
You are right, Keith. Depending on hemisphere and direction of travel the constant gyro track could be north or south of the great circle. I only meant that, in this case, it ran to the north.
3rd Feb 2017, 20:59

Join Date: Dec 2015
Location: France
Posts: 434
https://i.gyazo.com/a2658fc2c278618a...16ebb829d0.png
Doesn't it rather depend on the latitude for which the compass was made ?

By the way, suppose I buy a compass for 45N and go use it at 45S : won't it be totally upset and not horizontal ?
How can you have a compass fit to use from -45S to 60N, an amplitude which many long haul aircraft have ? (I know they have real means of measuring heading, but there must be an is a standby/emergency compass in these aircraft as well)

Thanks
4th Feb 2017, 09:34

Join Date: May 1999
Location: Bristol, England
Age: 60
Posts: 1,472
It does, there are compasses made specific to hemisphere but I have only been able to find references to 'orienteering' style compasses. I concluded that aircraft compasses are not compensated for hemisphere but cannot actually confirm that, its just not mentioned anywhere I can find. It makes sense, though.