View Single Post
  #7  
Old January 28th 05, 09:03 PM
Peter Bjoern
external usenet poster
 
Posts: n/a
Default

On Sun, 23 Jan 2005 18:38:16 -0700, wrote in rec.aviation.misc:

I maintained I didn't think any commercial routes went directly over
the pole or north of 80 N.Lat because the great circle routes from
say San Francisco to London didn't go that far north.


In short, are there any commercial routes flying over 90 North?


Routes from Scandinavia to the US west coast regularly goes over 90 North.

SAS (Scandinavian Airlines System) pioneered commercial flights over the pole
back in the 50's.

The first commercial polar flight was the DC-6B flight from Copenhagen to Los
Angeles on November 15th 1954.

Today with modern navigational aids such as INS and GPS, navigation is of course
not a problem, but back in the 50's it was a different manner.

Short distance (relatively) radio navigational aids like VORs and NDBs were not
present or usable in the polar regions (as is also the case over the oceans such
as the North Atlantic), so LORAN was commonly used for navigation.

Because the longitudinal lines are rapidly converging near the poles, navigation
with reference to the normal lines was not possible. A plotted straight line
near the pole would cross the longitudinal lines at such rapidly changing angles
that you would have to constantly make very major changes to your course to
maintain a straight line of flight. And then the magnetic compass was useless so
close the magnetic pole.

So a new concept of so called "grid navigation" had to be developed. An
artificial grid of parallel lines was overlaid on the polar region maps and the
courses were plotted with reference to the grid lines, thus having a straight
line of flight crossing the grid lines at a constant angle and therefore a
constant course. The heading was determined by use of a gyro compass which was
set before entering the region where the magnetic compass became unusable.
Positions were then obtained by dead reckoning, LORAN navigation and also
celestial navigation.

Regards

Peter