Celestial Navigation with X-Plane 11 - Part 2 - The Sight Reduction Method

Originally published at: http://www.mudspike.com/sight-reduction-method/

We continue our look at celestial navigation in X-Plane 11 with a breakdown of The Sight Reduction Method with Guest Contributor Cygon Parrot… Part 2 The Sight Reduction Method that will be described in the following text does not depart from PaulRix’s description much, except in one major way; you must assume you do not…


Grab your coffee for this one guys! Thanks to @Cygon_Parrot for the superbly detailed tutorial on how to work through the Sight Reduction Method. I think we should all be required to do this on a small commuter plane in turbulence or while balanced on the rail of a ship bouncing around in heavy seas… :rofl:

I want to see the Master Navigator do all the calculations in pen…!


So do I, whoever it may be, LOL!

I have already done it over a dozen times back in October, when testing results of the VB SRF application. In his/her absence, however, I would gladly walk through it again, if anyone is really interested.

As this is the “official thread”, I will upload said application right here; it makes the whole process extremely easy, and the tutorial for it is in the related article itself, skipping forward to half way through it.

Here is the application, for Windows…

VB_SRF.zip (18.7 KB)



Superbly done, just a staggering amount of data alone in the charts ! I was a Physics Major and am used to endless but always useful data of many kinds, but what you guys have done so far is amazing. I graded Engineering Students Term Papers that could not hold a candle to this Series of Articles .

Bravo !


@JunkYardDog On behalf of the “team”, and I am positive they will agree; many thanks for your comment!

Probably my own favorite subject, though I am extremely rusty. I now know who I can bother when I run into a brick wall with some problem in the future. :smiley:

Not seen you around before (as I was off for a while), and notice you have recently joined MudSpike. Therefore, a big “welcome” to you!


@Cygon_Parrot ,

At a hard lived 51 , I am lucky to remember I went to College, much less what I studied :slight_smile: I also did a fair amount of classes in PolySci , as I loved to debate , and still do.

Goes without saying some pretty hard core mathematics classes as well. It came to a point, I was the only Anglo Saxon person in most my classes. ******This is merely a statement of fact and in no way a race remark . *********

Most of all, Thank You Sir, for the kind words of welcome ! I snuck in late one night, someone left the door unlocked and I was in and claimed a spot before they could run me off :stuck_out_tongue:

As a final note, the Good lord blessed me with both Math and Reading/Reading Comprehension skills far above the norm , and they have served me well over the years.

The price for that though, is I can barely spell CAT , without having to ask one of my kids for help … lol

Cheers, and Well met indeed !


I would also like to add to my reply this … Please tell your team , and for yourself as-well , I for one, found the articles so far published not only highly interesting and of great value, but also superbly written, and the research done impressive on a Grand scale .

Much like Latin, Celestial Navigation is a a stone of import in the foundation of “Modern Society” ’ and much again like Latin, a dead or dying branch of knowledge that will be sorely missed one day. I am sure of that.

Outside of some Pilots and Ship Captains, there are so few with the skill left Sadly these days, there are so few among us on this little rock we live on that even bother to look up at Stars.

Preferring instead to go head down through their lives, usually staring at a cell phone, and blissfully ignorant and unaware of the beauty in both Heaven and Earth . This is not meant as a insult towards " the sheep " , just once again stating a reality.

If time permits you too, one day I would be interested in knowing the what brought forth the birth of such a topic , as it relates to X-Plane , and as to the mind(s) with the depth to bring it to fruition.

Respectfully ,



I can’t speak for the Celestial Brat Pack…but I think one of our long distance fly-in events had a significant overwater leg…

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…and let me add my welcome!

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I think that the subject first came up on the 2017 Christmas trek…

At the time there was no way to do it though. @TheAlmightySnark Casper made it possible when he wrote his app to pull the position from X-Plane and inject it, in real time, into Stellarium. After that it was a case of learning how C-Nav worked… and there was a lot more to it than I first imagined. Fortunately, @Cygon_Parrot asked if he could try his hand at it last Spring and soon became the third ‘musketeer’ so to speak. He has been able to take it several steps further than I did. It has been a fun project.

@JunkYardDog, Welcome aboard ! Glad to have you with us. If you give the tutorial a try, please let us know how you get on… :slightly_smiling_face:


Thank you Boss,

for both reply and the welcome. I am very glad to have found this wonderful blend of Humor and Sanity.

The places on the Web where one can have both ,a good laugh and reach back to the young man man in himself, and in the very next breath have a meaningful and well versed discussion on any number of topics can be counted on one hand. With fingers to spare.

I hope , and I am sure of it actually , that most users here appreciate the value of this website. (Website being a poor description in my mind, its is far more than that.)

It is no small praise when I say that you gentlemen that created this , and also now are tasked with the “herding of all us cats” , have gone far above and beyond the call !

Regards ,


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Thank you Mr. Rix for the welcome, and i will give that a try here relatively soon. Still a bit under the weather but getting better everyday now. Was a couple days last week I was not so sure I would be able to say that.

To see you say ,

[quote=“PaulRix, post:10, topic:10015”]
and there was a lot more to it than I first imagined.
[/quote]" brought a smile to my face , I remember a time, many years ago when my grandfather , a USN WWII Vet and did it on a Tin Can , told me he wanted to teach me Celestial Navigation.

Having already taught me to do Algebra , in my head no less , he was sure his young 12 yr old prodigy was up to the task This however was a job that tried both our patience . Taking a 12 year old young man outside after midnight is not the best way to gain and hold his attention. Add to it my utter fascination of the Universe and all things Stars , I had many questions for him, just none on the subject of Navigating this planet :slight_smile: . It never occurring to him that you could just as easily Navigate the Universe with this skill, and I had anything but navigation on my mind. Had he put it in those terms though, he may never have gotten back to the house before dawn.

Was some time later, after he left us, I was given the first choice of his many books he gathered throughout his life , and one was on this very topic. Knowing I was just as smart as any person that ever lived, or so I thought lol , I sat down and read a chapter or three till I realized two undeniable truths .

One being that , Oh Dear lord this is going to be impossible to do without some kind of interaction with the appropriate tools of the trade and someone that could present answers to my questions that understood the way I learned. The other , I had, at 12 years old let a opportunity that may never come again slip by me, as it was very clear that what he was attempting to teach me would have been like learning about Philosophy from Plato.

That was my last time with any real time spent on the subject , and when this article popped up here I could not help but smile at the memory. that smile quickly turned into a look of consternation as I started reading and the harsh truth of the fact I may now not be as smart at 51 , as I was at 20 . :stuck_out_tongue:

I intend on spending more time with the articles and putting more effort into finally grasping at least a general basis on things , as soon as I can. If nothing else, I owe it to the memory of a man who’’ intellect was so large , but not near as large as that of his humble nature," it profoundly impacted my life and the way I have tried to raise my children to be as well.

I will let you know how I get on once I am well enough to give it the attention it deserves .

My gratitude and the joy I gained from the memory it brought to my mind, is a debt that I will never be able to pay !

Cheers !


'68, @JunkYardDog? Snap!

I have a similar story from my childhood. In short, could it have been this book that you have?


1939 publication, USN. It has been in the family for years. I shared the relevant chapter on celestial navigation, scanned, with the team as a further resource during the development of the project. I will share it here for your good self (and anyone else who dares, too!), in case it is different from your book.

CelestialNavigation.pdf (2.1 MB)

It is a complex subject. I can confidently say, completely unabashed, that the introduction written by @PaulRix, published in Part 1, is by far the most clear, concise and easy to follow descriptions of the subject I have ever read. Sure, an initiate will need to stop, think and do a couple of exercises at the end of every couple of paragraphs, but you do come away from it with more answers than questions, which is the inverse situation of many other texts regarding :smiley: .

I could not agree more. I learned, in my youth, that a good starting point for anyone interested in history who does not know where to begin, perhaps, need only embark on the voyage of studying that area I term “the really interesting history”, aka, the age of exploration and expansion, through the study of ships (and how their crews found their way around). The rest falls into place by itself.

All the best, and, like @PaulRix, I do hope you find the time to give this archaic navigation technique a try! After all, even GPS has its roots in it, and how it works is not a 100 miles away from the same principle.

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One of the nicest sites on the net has picked up your article guys - Rock Paper Shotgun’s The Flare Path by Tim Stone (one of the best internet writers ever) featured it in his A2Z column:


That’s pretty neat! Thanks for the heads up Chris!


It’s interesting how circular life can be. Just last night I talked to a man who, other than my dad and my flight instructor at the time, I once respected more than any other man I knew. Its been 35 years since we had spoken. In his late eighties today, he still somehow commands respect. His name is Jim Smiley and I mentioned him briefly in another post I wrote today. When I knew him he was a 747 Captain for Pan Am. Before that he flew Delta Darts in the USAF. When I was 18 I asked him what was the hardest thing he had ever done—thinking it would be some risky night mission on the deck at mach 2. He said, hands down, Pan Am Nav School. It nearly killed him.

I now see why. Thanks for the huge effort you guys. You presented a very tough subject extremely well. Sometime soon, if it hasnt happened already, a non-pilot is going to find his/her way here because nowhere else on the internet is this explained so clearly.


Uncanny. I find its circularity happens far too much, almost beyond coincidences, sometimes.

Just spotted you glider article, incidentally. Having a read in a moment.

Nice, @BeachAV8R. Never seen that site before. There are a couple of games in that column that really got my interest, too. You can probably guess which :wink:

Tim Stone, author of that site’s “The Foxer” and “The Flare Path” is one of my nerd crushes. His writing style, unique humor, and love for esoteric topics is compelling. Much like I love just watching a Tarantino movie for the dialog, I love reading his articles for the way he winds through a topic.


Guys… this is fantastic work.

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Oh wow, I never figured I’d be featured in The Flare Path! That is by far my favourite bit of RPS ever since it got started… I’m a bit baffled!

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