A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Antoine Couëtte
Date: 2016 Sep 28, 20:34 -0700
That's me again ...
Well, I must have been very tired yesterday ... I do now know your own coordinates for Lady Moon (thanks again), but if I want to entire compute again Lunars #1, #2, #3 and #4 as I earlier did with exactly the same data as yours, then I also need the Sun 3D Coordinates (RA, Dec. and Distance to Earth) in the same reference frame as you used yesterday for the Moon.
Sorry to be so slow at reacting .... but yesterday early morning was quite intense.
Just when we were commencing our Inital Approach to our UAE destination with our few hundreds of passengers after our 12 hour long mostly night flight, low level stratus appeared all around totally unexpected lowering the visibility to less than 100 m in a a couple of minutes. Our Destination Airfield did not have Cat III A/B ILS, not even Cat II ILS, (very roughly speaking: no "autoland" capabilty), just CAT I: 550 meters RVR (slant visibility) with "manual" landing required (unless in Emergency). Hence we had to loiter and wait until the weather would end up clearing up, which it eventually did. These holding times are always very long and very short at the same time because on-board remaining fuel always shows the same trend and you are extremely busy. You are constantly re-evaluating the situation: "Are we going to stick to our Destination Airfield ?" (benefits and drawbaks) or "Are we going to divert, and if so to which Airfield, and if so no later than which fuel remaining deadline ?" (benefits and drawbacks), or "Are we going to loiter here as long as possible ?" "What is the weather trend here and elsewhere ?". You need to coordinate your decisions with Air Trafic Control (ATC) whom you can most often hear as being quite calm (very good !). You have to anticipate and arrange well in advance your possible diversion to an Airfield agreed by all parties involved and concerned ... a great number of questions which have to be adressed in limited time and in the right order to avoid ending up declaring an emergency. It took us 20 minutes in the stack to clarify all these points and to get ATC fully prepared in case we would end up needing last minute "short cut" Radar Vectors to our chosen diversion Airfield (where the visibility was also very bad, but which did have CAT I, II, IIIA and IIIB available). Then we had to loiter another lenghty 20 minutes before we could resume our approach to destination. These total 40 minutes of constant decisions reassessing under unescapable time pressure were quite long. Safely landed at our Initial destination Airfield with more than 3 km visibilty, a still quite low and very dazzling morning Sun, but our landing QFU was 290° :-) !
In comparison, in "Blue Water" operations on Aircraft Carriers in the middle of nowhere (no diversion airfield), it is much more simple: you proceed to the in-flight Refueling Tanker and afterwards you wait until the Carrier is ready to take you on-board or until there is no fuel left anywhere up in the air, whichever comes first. Quite simple indeed: first airborne refuel, then either recover on-board, ditch or bail-out.
Sorry for this off-topic diversion ... Frank please, do not frown upon me ...
Paul, thank you again in advance for your own Sun 3D coordinates.