Greatcircle Distance

Hello every one,

I am wondering if somebody could help me out with the following:

How is the Greatcircle distance calculated in AE? Does somebody has a formula, because the one I use (below) gives a significant difference in NMs

Cos(DGrC)= Sin(La)xSin(Lb)+Cos(La)*Cos(Lb)*Cos(dLab)

DGreatcircle(NM) = 60*ACos[Cos(DGrC)]

where:
DGrC=Distance Greatcircle
La = Lattitude pointA
Lb = Lattitude pointB
dLab = difference longitude pointA and pointB

Just curious.


Fokkerfly, CEO ACA

Hello every one,

I am wondering if somebody could help me out with the following:

How is the Greatcircle distance calculated in AE? Does somebody has a formula, because the one I use (below) gives a significant difference in NMs

Cos(DGrC)= Sin(La)xSin(Lb)+Cos(La)*Cos(Lb)*Cos(dLab)

DGreatcircle(NM) = 60*ACos[Cos(DGrC)]

where:
DGrC=Distance Greatcircle
La = Lattitude pointA
Lb = Lattitude pointB
dLab = difference longitude pointA and pointB

Just curious.


Fokkerfly, CEO ACA

u think we are all related to Albert Einstein

u think we are all related to Albert Einstein

Aren't we all? :saint:

Someone with an anwser I can use?

Krgds, Fokkerfly

Well, I would use the same formula, or better said, it looks like the one I always use. But I don't know if this is the one used in AE. I know the coordinates of each airport are in the database, but maybe they use something more simple, maybe based on a Mercator chart or so. Is it a big difference you are having with your own calculations?

Felix

Is it a big difference you are having with your own calculations?

Felix

well, AE calculates for ATL-BOS 946NM, with the above formula I'll get 942NM. So a difference of 24NM can be significant don't you think?

Fokkerfly

The question is also if you and AE use the same coordinates for each airport. With big cities like Atlanta it is quite easy to get such deviations if the exact coordinates for the airport are not used (and even the airport itself is quite big, so the question is where to pick that point on the airport). There will be no chance of changing that for now anyway. Hopefully someone of the developers team reads this post, so that things are exact in version 3 of this game.

Cheers,

Felix

well, AE calculates for ATL-BOS 946NM, with the above formula I'll get 942NM. So a difference of 24NM can be significant don't you think?

Fokkerfly

Are we sure its all nm?

Now that you mention it... The game calculates everything in statute miles, not nautical miles. This makes the error even bigger. Seems to be quite messed up here...

Felix

well, AE calculates for ATL-BOS 946NM, with the above formula I'll get 942NM. So a difference of 24NM can be significant don't you think?

Fokkerfly

you mean 4 NM difference... right? 946-942=4.

in all the trig...he somehow found 20 extra NM...

I think he meant: "AE calculates for ATL-BOS 964NM, with the above formula I'll get 942NM", which is a difference of 24N you smartasses. The system calculation is wrong anyway...

Cheers,

Felix

Felix... that gives a difference of 22NM...

which is a difference of 24N you smartasses.

Theres no need for that kind of language, we are all prone to make mistakes and your entitled to make them too!

you mean 4 NM difference... right? 946-942=4.

sorry to all replied, I have to make my calculations right when I post here. The following result is true for ATL-BOS:

coordinates:
ATL 33°38’ N, 84°26’ W
BOS 42°21’ N, 71°0’ W

AE Distance is 946 miles (Don't know wheather it is SM or NM)
according to my formula it is 821NM
The correct difference is 946-821 = 125

that is already some difference!
following for ATL-AMS

ATL 33°38’ N, 84°26’ W
AMS 52°17’ N, 04°45’ E

AE distance is 4389 miles
my calculation results: 3813NM

so difference with the game is 4389 - 3813 = 576 miles

I'm a pilot myself and when I have these errors I won't start my flight across the atlantic!

The reason I want to know the way AE is calculation distances is that I am working on a tool for all of us to use helping managing the AE fleets we have, but for that I need to know the right formulas, otherwise it makes no sense.

Fokkerfly