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# Flight Distance

Afaceinthematrix
Earlier, I was talking with someone about the longest possible flight distance from where we live (Southern California). We agreed that we'd probably leave from Los Angeles Airport (LAX) because that is the biggest airport around. He thought that the longest flight would be to Mozambique in southeasten Africa. That didn't seem right to me; somewhere in Australia seemed more likely. So what I did was go look up the coordinates of LAX Airport - which are 33°56′33″N 118°24′29″W. I then went to Google maps and typed in 33°56′33″S 118°24′29″E and got Mindarabin, Australia - which was in the country that I originally guessed. Was my logic correct (I want to know before I go and say "I told you so!"). I just put in exact opposite coordinates and I should get the furthest point away - correct? Also, does furthest distance necessarily imply furthest flight (we are assuming nonstop)? I am sure that there is possibly some situation where an airplane can't fly over certain air spaces or to where a plane flies in a certain path for optimization since our planet is not a certain sphere... I just wasn't sure about my logic...

By the way, I am ignoring the fact that Mindarabin may or may not have an airport. This was mostly an argument about the furthest place away from us more than furthest flight...
kelseymh
 Afaceinthematrix wrote: Earlier, I was talking with someone about the longest possible flight distance from where we live (Southern California). We agreed that we'd probably leave from Los Angeles Airport (LAX) because that is the biggest airport around. He thought that the longest flight would be to Mozambique in southeasten Africa. That didn't seem right to me; somewhere in Australia seemed more likely. So what I did was go look up the coordinates of LAX Airport - which are 33°56′33″N 118°24′29″W. I then went to Google maps and typed in 33°56′33″S 118°24′29″E and got Mindarabin, Australia - which was in the country that I originally guessed. Was my logic correct (I want to know before I go and say "I told you so!"). I just put in exact opposite coordinates and I should get the furthest point away - correct? Also, does furthest distance necessarily imply furthest flight (we are assuming nonstop)?

Yes, your logic was correct. On a sphere, the point at maximum distance from a given point is the antipode. Using latitude/longitude coordinates, you can always identify the antipode by reversing both directional references, just as you did above.

The relationship of "longest flight" to "farthest distance" only applies if the plane can flight a great circle route. Real air transport does use great circle routes where possible, there are several complications:
* restrictions on different countries' airspace;
* aircraft follow paths between designated control points;
* aircraft must remain within a minimum distance of some large airport (so they have somewhere to land in case of problems);
* prevailing winds make direct great-circle paths across the equator difficult.
Afaceinthematrix
 kelseymh wrote: Yes, your logic was correct. On a sphere, the point at maximum distance from a given point is the antipode. Using latitude/longitude coordinates, you can always identify the antipode by reversing both directional references, just as you did above.

No. My logic actually wasn't correct. I was thinking last night while lying in bed that I made a very obvious mistake: since we don't live on a perfect sphere, our longitude lines curve. So it works for the latitude but not for the longitude. I used a globe to estimate it and it looks like my solution should be somewhere in the Indian ocean which means that a flight to Madagascar might be longer than a flight to Australia.

 Quote: The relationship of "longest flight" to "farthest distance" only applies if the plane can flight a great circle route. Real air transport does use great circle routes where possible, there are several complications:

I also knew about the great circle route but I wasn't sure exactly how this was set up in respect to longitude and latitude lines. When I fly I like looking at the flight path that is sometimes shown to passengers. An easy experiment that I did to see what would probably me my route when I flew overseas a few months was place a thumbtack in my departure city and then arrival city on a globe. I connected the two with a piece of string and pulled saw what used the least amount of string.
ocalhoun
Longest existing flight or longest possible flight?

Longest existing could probably be figured easiest by looking up flight times for likely destinations.

Longest possible is just a simple matter of the aircraft's range... after all, who said you had to take the shortest route anywhere?