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    Re: DR vs EP vs MPP vs Fix vs Running fix
    From: Ken Gebhart
    Date: 2002 Feb 1, 19:00 -0600

    Gentlemen,
    This has been a most interesting thread of discussion. I had no idea that so 
    many were (or had been) involved in air navigation. I was a U.S. Navy Patrol 
    Plane pilot in the early sixties. In those days we had no navigators, so the 
    youngest pilot had to do that chore. I had several thousand hours navigating 
    all over the Pacific with only celestial and a drift meter. I later got an 
    FAA
    Flight Navigator License.
    
    This discussion has been a wonderful recollection of all the terms and 
    concepts of navigation with which I was intimately familiar. So, the 
    disparity in terms got my attention. My 1966 edition of Bowditch has 
    discussions and definitions for course, track, etc for both air and marine 
    navigation.  The book actually makes the distinction between the two, and 
    acknowledges that some
    definitions are in fact different, as has been discussed here.
    
    Lastly, in reply to Sherman's poll - certainly a DR is the best possible 
    reckoning of where a vessel will be at a given time, using all possible 
    information. It is the position to which a rescue vessel will proceed if you 
    need help. You would not want to omit any pertinent information in 
    calculating it.
    
    Ken Gebhart
    
    Jared Sherman wrote:
    
    > Chuck - and all-
    >  <"The DR position is only an approximate position because it does not allow
    > for the effect of leeway, current, >
    >  Is there anyone here who would "reckon" their position without attemping to 
    factor in ALL known effects? If one is plotting a DR position while crossing 
    the Gulf Stream, even without knowing the current, is there anyone who would 
    not indicate *some* offset as a best guess of the current, since they 
    approximate current direction and speed are almost certain to exist to some 
    extent?
    >
    > I ask this as a poll, not as an arguement. My understanding of DR, the good 
    Mr. Bowditch aside, was that a navigator placed EVERYTHING he could into the 
    DR position and that it was supposed to include all "guestimates" of where 
    you actually were, not just ignoring the ones you couldn't specify to five 
    decimal places.
    
    
    

       
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