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    Re: A navigation exercise
    From: Antoine Couëtte
    Date: 2010 Mar 31, 22:29 -0700

    Hello Jeremy,

    You just indicated :

    QUOTE :

    At the Lunar time, which was 1616-43 LT, I was having a bit of trouble with clouds. The first set of sun/moon altitudes were at 1612 and 1613 respectively, and the second set were 1617 and 1618. The GPS position was 7 deg 03.6' S and 72 deg 7.0' East. This was certainly better than most of my sun-moon lunars which seem to be far less accurate for me than other lunars.


    So, you did write down the times of your 4 height shots. This is excellent and thank you !

    In [NavList 12565] Date: 28 Mar 2010 01:56, the published results of your Lunar are already quite close from actual position ( less than 3 miles ). Although your height observations took place during a reduced time span (16:12 - 16:18), there is still some uncertainty in my results since I had to assume that all heights were taken at the same time. So there is probably some "chance" in these earlier results.

    Would you have also recorded Course (CMG) and Speed (SMG) during this 16:12-16:18 Period ?

    It would enable to rework your Lunar with better assumptions than mere estimating that you Ship was not moving at all, and accordingly improve the confidence level of such upcoming results, even if the final output might somewhat show further away from the GPS FIX than the earlier [NavList 12565] fix.

    GPS is just great to independently - and generally most reliably - cross check CelNav results.


    Anyway, it looks like your are close to Bengla-Desh now ... In 2007-2008, I landed my Cargo DC10-30 (I-CGIA) 19 times in Dhaka.

    Thank you for your Kind Attention, and

    Best Regards

    Antoine M. "Kermit" Couëtte

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