AIR NAVIGATION METHODS IN THE 

 POLAR REGIONS 



O. M. Miller 



Aerial navigation generally will never call for such precise de- 

 terminations of position as navigation at sea, and it is quite sufficient 

 for the aerial navigator to fix his position within a radius of ten miles. 

 In considering the methods of navigation that will be described in 

 the present paper this point should be kept in mind. 



The subject of navigation can be dealt with in two parts; the first 

 of these is position finding, and the second direction finding, which 

 includes the operations involved in steering a course. 



Position Finding 

 By Dead Reckoning 



To deal with position-finding methods first, dead reckoning is 

 the principal method used by all navigators and is simply the process 

 of determining position by distance and direction flown from a known 

 starting point. In the polar regions the method dififers in no essential 

 from ordinary practice in aircraft.^ 



Its accuracy depends on the ability of the navigator to judge 

 ground speed and to correct for the drift of the aircraft from the 

 desired direction due to lateral wind pressure. In order to do these 

 things, at present, it is necessary to know the air speed, the height of 

 the aircraft above the surface of the earth, and to be able to see the 

 latter, which should not be entirely featureless. Obviously, over the 

 open sea, it is only possible to get a very approximate result by this 

 method, but over an ice field, which is by no means featureless, suf- 

 ficiently accurate results can be obtained, as has been demonstrated 

 by Commander Byrd in his flight to the pole. As in all forms of 

 aerial navigation, fog is the arch enemy of dead reckoning. Even 

 supposing the navigator can be sure of steering in a straight line 

 through it, there is still the difficulty of determining ground speed. 

 The whole problem of dead reckoning through fog needs a practical 

 solution. 



By a Position-Line Method 



Fog or no fog, the navigator cannot allow himself to place full 

 reliance on the dead-reckoning method. He must have other means 



1 See H. N. Eaton: Aerial Navigation and Navigating Instruments, Natl. Advisory Committee 

 for Aeronautics Rept. No. 131, Washington, 1922. 



445 



