> The article implied that the automated system would allow for > /shorter paths/ (the shortest path is the great circle, so this > statement indicates that trans-oceanic flights are not using great > circle/GPS routing). Most likely, the flights are using 50 minute "plumb > lines", with a heading change at the 50 minute mark, so current position > and new heading can be reported to ATC. GPS may be supplying the pilots > with position info, but they may not be free to make the constant > heading changes... The automated system may send this information > digitally at much higher rate than 50 minutes, allowing ATC to plot near > realtime positions.
Looks as if I stand corrected - I remember clearly when we were introduced to great circles in school, that the example given were intercontinental flights. So it appears that they use a discretization scheme that our teacher embezzled. Terry Pratchett calls that "Lies for kids". On further thinking, it makes sense that it's not allowed to constantly change heading - it makes the course estimation for e.g. approaching aircrafts complicated. Thanks for pointing that out! Diez -- http://mail.python.org/mailman/listinfo/python-list
