04-08-2023, 03:28 PM
HI, Ed,
It sounds as if you have got this squared away.
I am pleased that you actually did the sight reduction and plot from both AP's to see that the resulting LOP's are both valid. It is one thing to be told that is so and another to see it for yourself and to report your results to others. Thanks for that.
There are two other minor points that I'd like to add at this stage:
ONE:
The "...less than 30 minutes of longitude from your DR..." requirement also exists when working exam problems in Western longitudes. All for the same reasons -- which is to get an answer that matches the examiner's.
TWO:
In actual navigation you may have a DR that is way off for various reasons. In that case you could easily end up with an AP far from your actual position resulting in long intercepts. That's OK. If you find yourself in this situation -- and you are absolutely sure you didn't blunder in your sight reduction process -- simply use the new "fix" as an updated DR. Derive a new AP from that point and re-do the sight reduction from there. The updated fix obtained by this method probably won't be different from the first one by more than a handful of miles.
Peter
It sounds as if you have got this squared away.
I am pleased that you actually did the sight reduction and plot from both AP's to see that the resulting LOP's are both valid. It is one thing to be told that is so and another to see it for yourself and to report your results to others. Thanks for that.
There are two other minor points that I'd like to add at this stage:
ONE:
The "...less than 30 minutes of longitude from your DR..." requirement also exists when working exam problems in Western longitudes. All for the same reasons -- which is to get an answer that matches the examiner's.
TWO:
In actual navigation you may have a DR that is way off for various reasons. In that case you could easily end up with an AP far from your actual position resulting in long intercepts. That's OK. If you find yourself in this situation -- and you are absolutely sure you didn't blunder in your sight reduction process -- simply use the new "fix" as an updated DR. Derive a new AP from that point and re-do the sight reduction from there. The updated fix obtained by this method probably won't be different from the first one by more than a handful of miles.
Peter