# The Opposite Side of the Earth | General Navigation | ATPL Question Bank | AE67132 – Answering ATPL

Hello Youtube, Welcome to Answering ATPL Today we will look into General Navigation subject. The topic for today is Basic of Navigation the Earth. Position on the Opposite Site of the Earth. The coordinates of the heliport at Issy les Moulineaux are 48°50’N 002°16.5’E. What are the coordinates of the position directly on the opposite side of the Earth? The question were asking about the position on the opposite side of the earth. What does it really means is the antipodal position on the Great Circle. Our initial position is 48°50’N 002°16.5’E. Here ia the diagram to illustrate the problem at hand. Imagine this is the Earth, The given position at Issy les Moulineaux is A and the opposite position is B. How do we confirm that B is the opposite position of A. Imagine you have a stick, avery long stick. You [oke it at A through the center of the Earth it will come out at B. In our diagram the yellow stick does come out at B, Thus, position B is Antipodal position of A. As you can see from the diagram, Antipodal position is 180° away both in term of Latitude and Longitude. Thus, to find antipodal Latitude we just need to add 180°. 48°50’+180=228°50′ What actually happen? We know the maximum value of latitude is 90°. Let me explain it in more detail using an illustration. Imagine this is the earth from the front view. Here is the equator, and here is the North Pole, and South Pole. Here is our initial position A, and the opposite position B. The angle here is 48°50′ Here the angle is 180°. This angleshoul have the same value with its opposite side of 48°50′. but it is in the Southern Hemisphere. Thus the answer is 48°50’S. As for Latitude, the Longitude different between initial position and antipodal position is 180°. Thus, Antipodal Longitude=002°16.5 + 180° Lets bring back the calculator. 2°16′ decimal 5 is equal to 30″ …30″ plus 180° equal to 182°16’30” or 16.5′ 182°16.5’E We know there no such value of 182°. Because the maximum value for longitude is 180° Imagine this is the earth. We are looking at it from the top view, and the center of the cross is the North Pole. Here is the Prime Meridian, and here is the Anti-Meridian. 90°E and 90°W. Here is our initial position 002°16.5′, extend it to the opposite side. The angle between Prime Meriadian and the Antipodal position is 182°16.5’E. Our answer is the angle marked in blue, to get the angle marked in blue we need to substract 182°16.5 form 360°. 360°. is the total amount of angle from a complete circle. 360° – 182°16’30″=177°43’30” Because the Antipodal postion lies within the Western Hemisphere The answer will be 177°43.5’W Thus our answer will be 48°50’S 177°43.5’W The answer is B. To answer this question quickly… Just change the sign of the given Latitude from North to South or South to North, and given Longitude minus 180°. That will be all for this video, if you have any question or comment please leave it in the comment section, thank you. Thank you for watching. Please subscribe and checkout other videos.