PPL QUESTION
Thread Starter
Join Date: Jan 2014
Location: Uk
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
PPL QUESTION
Hi Guys,
Ive been revising for my Air nav exam which i hope to do next week, however, i can't for the life of me work out how to do this question and cant find anything on the internet:
An aircraft travels north along the same meridian from latitude 30 15’ south to 14 00’ south. What is the distance flown in kilometres?
Correct answer: D - 1806 km
i also use PPLTutor which is a great help. It tells you how to answer questions like this but i get a different answer ill post the PPLTutor page below:
E.g. An aircraft travels south along the same meridian from latitude 27°30'N to 02°15'S. What is the distance flown in kilometres?
27°30'N + 02°15'S = 29°45'
29°45' x 60 = 1785nm.....................HERE I GET 176700?????
1785nm x 1.852 = 3305.82 km
any help will be much appreciated.
Cheers
Matt.
Ive been revising for my Air nav exam which i hope to do next week, however, i can't for the life of me work out how to do this question and cant find anything on the internet:
An aircraft travels north along the same meridian from latitude 30 15’ south to 14 00’ south. What is the distance flown in kilometres?
Correct answer: D - 1806 km
i also use PPLTutor which is a great help. It tells you how to answer questions like this but i get a different answer ill post the PPLTutor page below:
E.g. An aircraft travels south along the same meridian from latitude 27°30'N to 02°15'S. What is the distance flown in kilometres?
27°30'N + 02°15'S = 29°45'
29°45' x 60 = 1785nm.....................HERE I GET 176700?????
1785nm x 1.852 = 3305.82 km
any help will be much appreciated.
Cheers
Matt.
Join Date: Aug 2002
Location: UK
Posts: 740
Likes: 0
Received 0 Likes
on
0 Posts
You have done 2945 x 60 = 176700
1 minute = 1nm and there are 60 minutes in a degree. So 29 degrees -> 29 x 60 = 1740nm
and then add the 45nm for the 45 minutes -> 1740 + 45 = 1785nm
For the Question you asked first. 30 15' S to 14 00' S -> 16 x 60 +15 = 975nm
Use your conversion of 1.852 -> 975 x 1.852 = 1805.7km Answer D.
1 minute = 1nm and there are 60 minutes in a degree. So 29 degrees -> 29 x 60 = 1740nm
and then add the 45nm for the 45 minutes -> 1740 + 45 = 1785nm
For the Question you asked first. 30 15' S to 14 00' S -> 16 x 60 +15 = 975nm
Use your conversion of 1.852 -> 975 x 1.852 = 1805.7km Answer D.
Join Date: Jun 2012
Location: Cambridge
Age: 38
Posts: 60
Likes: 0
Received 0 Likes
on
0 Posts
So, one minute of latitude = one nautical mile. As such our first job is to get our difference into minutes - taking the 29 degrees 45 minutes example, we need to multiply the 29 degrees by 60 (as there's 60 minutes in a degree), then add the 45 minutes, thus the calculation is 29*60 + 45, which comes out as 1785 minutes, which is equal to 1785 nm.
In the case of your question, we have 16 degrees 15 mins, so 16*60 + 15 = 975nm. 975 * 1.852 = 1805.7 or 1806 to the nearest km.
In the case of your question, we have 16 degrees 15 mins, so 16*60 + 15 = 975nm. 975 * 1.852 = 1805.7 or 1806 to the nearest km.
Looking at your post above:
Your mistake is that you have multiplied the number 2945 by 60 to get 176700.
You have overlooked the fact that 45 minutes is 3/4 of a degree, so 29°45' is 29.75 degrees.
If you multiply 29.75 x 60 you will get the correct answer of 1785.
If you go on to do the ATPL exams you will spend many hours practicing this type of stuff and you will need a calculator which is able to handle minutes, degrees and seconds. But that is all tomorrows nightmare, so it's nothing to worry about at the moment?
29°45' x 60 = 1785nm.....................HERE I GET 176700?????
You have overlooked the fact that 45 minutes is 3/4 of a degree, so 29°45' is 29.75 degrees.
If you multiply 29.75 x 60 you will get the correct answer of 1785.
If you go on to do the ATPL exams you will spend many hours practicing this type of stuff and you will need a calculator which is able to handle minutes, degrees and seconds. But that is all tomorrows nightmare, so it's nothing to worry about at the moment?
And if the CAA was cruel enough to have the aircraft flying along a parallel of latitude, you would do the same calculation i.e. converting the longitude difference to minutes and multiplying by 60 AND THEN multiply the answer by the cosine of the latitude, to allow for the convergence of meridians (assuming that the earth is spherical and not an oblate spheroid).
Hub61, regarding your comment below:
I'm not sure who you are aiming it at but:
If it is me, then yes 45 minutes of latitude change is 1 nm and yes 1 degree is 60 minutes. But looking at the initial question, it is clear that the author had mistaken 29 degrees 45 minutes for 2945 minutes. This is a common mistake made by students studying for the ATPL exams.
If your comment is aimed at India Four Two then although 1 minute change of latitude is equal to 1 nm, it is not always true that 1 minute change of longitude.
1 minute change of longitude is equal to 1 nm only at the Equator. But because the circumference of the Earth reduces as we move north or south towards the poles, the distance equating to each minute of longitude also decreases. So distance equating to each minute of longitude is 1nm at the Equator and gradually decreases to zero at the poles.
The parallels of latitude do not converge, so each minute of latitude is always equal to 1 nm.
is it not 45 miles?, whatever that is in KM
1 degree = 60 miles
1 degree = 60 miles
If it is me, then yes 45 minutes of latitude change is 1 nm and yes 1 degree is 60 minutes. But looking at the initial question, it is clear that the author had mistaken 29 degrees 45 minutes for 2945 minutes. This is a common mistake made by students studying for the ATPL exams.
If your comment is aimed at India Four Two then although 1 minute change of latitude is equal to 1 nm, it is not always true that 1 minute change of longitude.
1 minute change of longitude is equal to 1 nm only at the Equator. But because the circumference of the Earth reduces as we move north or south towards the poles, the distance equating to each minute of longitude also decreases. So distance equating to each minute of longitude is 1nm at the Equator and gradually decreases to zero at the poles.
The parallels of latitude do not converge, so each minute of latitude is always equal to 1 nm.
"The parallels of latitude do not converge, so each minute of latitude is always equal to 1 nm."
Wrong way round I think. Cosider parallel of latitude 89deg North. Its a lot shorter than the equator but still equal to 360 deg in circumference. Therefore 1 min in latitude at 89 north would be a lot shorter than 1 min of latititude at the equator. lines of longitude are the same length so i min of longitude at the equator is roughly equal to 1 min of longitude at 89 lat north. having said that 1 min of longitude soes shorten slightly as you near to the poles. The earth is not a perfect spheroid. Due to the fact that the earth is spinning the earth is not a perfect sphere. The equator (line of latitude) is longer than a line of longitude, i.e. the earth is "flatter" at the poles. GPS uses WGS 84 which compensates for the distance difference, which is why old charts which use a different WGS have to be adjusted in order to agree with the GPS standard. Sorry for going off thread but the original assertion is fundamental to navigation. You should always use the longitude lines for distance measuring on a chart, never the latitude lines which change with longitude.
Wrong way round I think. Cosider parallel of latitude 89deg North. Its a lot shorter than the equator but still equal to 360 deg in circumference. Therefore 1 min in latitude at 89 north would be a lot shorter than 1 min of latititude at the equator. lines of longitude are the same length so i min of longitude at the equator is roughly equal to 1 min of longitude at 89 lat north. having said that 1 min of longitude soes shorten slightly as you near to the poles. The earth is not a perfect spheroid. Due to the fact that the earth is spinning the earth is not a perfect sphere. The equator (line of latitude) is longer than a line of longitude, i.e. the earth is "flatter" at the poles. GPS uses WGS 84 which compensates for the distance difference, which is why old charts which use a different WGS have to be adjusted in order to agree with the GPS standard. Sorry for going off thread but the original assertion is fundamental to navigation. You should always use the longitude lines for distance measuring on a chart, never the latitude lines which change with longitude.
Join Date: Sep 2006
Location: Scotland
Age: 84
Posts: 1,434
Likes: 0
Received 0 Likes
on
0 Posts
Low level pilot has it right.
The explanation is confusing.
The last sentence is correct North-South minutes are constant in nm.
East-West minutes are not constant in nm.
Minutes are minutes in both directions.
Flattened spheroids confuse the issue.
Just my twopennorth.
The explanation is confusing.
The last sentence is correct North-South minutes are constant in nm.
East-West minutes are not constant in nm.
Minutes are minutes in both directions.
Flattened spheroids confuse the issue.
Just my twopennorth.
