Highlights from an earlier incarnation of the Forum:
http://tighar.org/Projects/Earhart/forum/Highlights61_80/highlights69.htmlSubject: RE: 10 miles or 100
Date: 1/3/00
From: Alan Caldwell
I think I told you I was trying to work the celestial backwards to pin down possible tracks or areas where the Electra could have been for Noonan to get a sun shot azimuth of 67 degrees. I have been working with the Dept. of Aerospace Engineering & Center for Space Research Engineering Mechanics at the University of Texas. I received a reply from that department this morning showing me how to make the computations. The preliminary results are general and as follows:
Using an azimuth of 67 degrees exactly and not a fraction off there was no place south of Howland inbound that Fred could have found a 67 degree azimuth. I recognize a slight deviation from exactly 67 degrees could have occurred but it would not change the general conclusion.
If they were on course due west of Howland inbound he had a 67 degree azimuth all the way.
They could also have been north of course as much as 120 nm but at about 200 miles west.
http://tighar.org/Projects/Earhart/forum/Highlights61_80/highlights69.htmlSubject: Re: 10 miles or 100
Date: 1/3/00
From: Alan Caldwell
Ric asks:
> Does this mean that in order to get a 157/337 sunrise LOP they HAD to be
> somewhat north of course at that time?
I wish I could answer that with a definite yes or no but it DOES appear that the answer must be yes. I checked all the coordinates south of 0 degrees 48 minutes North all the way back to 179W. It is possible but less than likely that 67 degrees could be found. But there are close fractions. The easy one would be 67.2 or 66.8 and if they are rounded off or Fred's sextant was not quite that accurate then he could well have been dead on course. I'll check out 77 degrees and see how it comes out but generally speaking I found little probability they could be south of a due east course.
http://tighar.org/Projects/Earhart/forum/Highlights61_80/highlights69.htmlSubject: Re: 10 miles or 100
Date: 1/4/00
From: Alan Caldwell
Ric asks:
> Is it possible to plot a band on a map which encompasses the locations
> where the airplane could have been and gotten a 67 degree sunrise (plus or
> minus a couple of tenths)?
Yes, but I won't have time to work on the 77 degree course thoroughly until this weekend but preliminary checks show that although a 67 degree azimuth could be obtained at 6:20a to 6:30a from 179W to 176W the sun's elevation was extremely low --- averaging only a degree and a half above the horizon with a maximum height of 3.3 at the 176W line at 6:30 and at that time They should have been somewhat west of that longitude, about 60nm or so. ( arbitrarily figuring 133k GS)
What that tells me is that they could have been on course but probably on a course somewhat due west to east or even slightly north of that track. There is a lot of room to maneuver and still find 67 degrees of azimuth but I suspect we will be able to eliminate being well south of Howland or well north. It appears to me from first glance your theory that they were pretty close to track and hit Howland fairly close is supportable. I think it also makes it more likely they missed Howland simply because they couldn't see it visually and not because of any gross navigation error.
Alan
#2329
From Randy Jacobson
This is kinda silly. FJN doesn't actually measure the 67 degree azimuth to the sun. He assumes a position on the globe, the books tell him when the sunrise is going to be and the azimuth. There will be a good range of latitudes that will give him that azimuth +or- a few tenths of a degree. He then compares the book time of sunrise to what he observes, and that gives him a correction towards/away from the sun along a 67/247 line. What's important is where Noonan THINKS he is, not where he really is, that determines the 67 degree line.
http://tighar.org/Projects/Earhart/forum/Highlights61_80/highlights70.htmlSubject: Re: 10 miles or 100?
Date 1/11/00
From: Alan Caldwell
> Is there a way that Randy's solution (and others for that matter)
> could be reproduced visually with step-by-step explanations, and then
> distributed in the next TIGHAR Tracks? This whole issue is VERY confusing
> to most of us and I think a "show-and-tell" approach would better educate
> all of us.
Dennis, you have hit on the very problem that caused me to post my first few notes.
It quickly became obvious from the postings that only a very few people on the forum understood, even vaguely, what an LOP was. Postings showed they didn't understand how Noonan could get on the LOP or know he was on it. Consequently I tried to craft an explanation of that one issue without confusing everyone more with a lengthy course on celestial navigation. An attendant problem was how to do that knowing there were a couple of people who DID know something about celestial procedures. I decided to totally ignore the dead reckoning (DR) portion (which I announced) and to do that I had to sort of fudge. I stated in one of my first notes that I was only dealing with the LOP issue and that what I was writing was technically NOT accurate and that this was not the way it was really done. I did that solely to eliminate all the work going into shooting and plotting the fix to show ONLY what an LOP was and why Noonan could know when he was on it whether he was ON course, or north or south of it.
While working on this it dawned on me that the 67 degree azimuth might be significant information so I contacted a number of professionals in this regard. After giving the background I posited that the 67 degree sun azimuth might tell us something as to where in general Noonan might have been during a very small time and position envelope. I contacted the US Naval observatory, the British outfit that publishes their air almanac, the aerospace mechanics and engineering department at the University of Texas, a Canadian government observatory and several other professional astronomers. All believed it was a reasonable and possible experiment and mathematically workable -- my detractors to the contrary.
One forum member who is quite knowledgeable of celestial procedures instead of seeing the possibility got side tracked by his accurate knowledge that a sun azimuth is not actually shot but rather only the altitude. This is true to a certain extent. The azimuth is instead plotted using the sun shot and the almanac tables. It also is shot using an azimuth circle which was a standard technique long before this particular flight. It is also true that when shooting the particular body the azimuth will tell the navigator valuable information.
The azimuth of the sun, contrary to what has been suggested, does NOT remain the same all day. It changes with the observer's time and position. If you will look at the sun data for Howland's position for the morning of July 2, 1937 you will see that the azimuth varies throughout the day. If you pick a position dead on the island and look in the table for a particular time, say 07:00a you will find a certain azimuth. If instead you pick a place 60nm dead north and check the table you will NOT find the same azimuth. It varies from north to south.
If you will picture yourself that morning 180nm west of Howland on a true course of 77 degrees and you look at the sun and note its direction, then picture yourself three or four hundred miles either north or south of that course and it should be obvious that the sun MUST be at a slightly different angle.
The bottom line is that there may be enough information to GENERALLY place Noonan between sunrise and 8:45 local.
While going through this exercise it also dawned on me that everyone has pretty much made the loss a navigation issue. Noonan has been restricted to only a sun line. He has not been allowed to shoot the moon or planets all of which was available to him that morning. I have also checked and found the data WAS available in the charts of the day. There were even SOME air almanacs but what they contained for the relevant period I haven't determined. I have found that the British air almanac was available but only for the last quarter.
We have not allowed Noonan to use an azimuth circle that was standard for the day nor have we even given him the reasonable possibility of checking his drift and ground speed. ALL normal navigation techniques that ANY navigator would have used let alone a MASTER navigator with years of nautical and Pan Am experience. In our rush to explain why they missed Howland we have stripped Noonan of all his great experience and expertise and the tools of his trade. We have created an impossible task for Noonan in addition by exploiting all the known celestial errors and variables and somehow implying Noonan would either not have known of them or could not take them into consideration. Some have even made him incapacitated from drink.
And yet the possibility that our duo simply could not visually spot a tiny island among all the cloud shadows seems too far out to accept. Interesting.
http://tighar.org/Projects/Earhart/forum/Highlights101_120/highlights112.htmlSubject: Erroneous Howland Position?
Date: 10/30/00
From: Randy Jacobson
Noonan’s 10 mile navigational uncertainty was based upon nighttime celestial navigation, shooting LOP’s from at least 2 or more targets. For the sunrise LOP, his precision of navigation would be that he could navigate the plane to within 10 miles of the LOP determination, but he would not be able to determine his position along the LOP at all.
http://tighar.org/Projects/Earhart/forum/Highlights121_140/highlights127.htmlSubject: Re: Professionals
Date: 2/19/01
From: Randy Jacobson
I've not piped up to date, but let's get something very clear here: FN did not navigate anywhere near 50 to 100 miles off his target. The Oakland to Honolulu maps indicate the plane was that far off the perfect rhumb line between the two points if and only if there was no winds aloft. Without real-time, constant navigational control, no navigator, repeat, NO navigator or pilot could or even would try and maintain that level of navigational precision to stay on a rhumb line over water. It simply wasn't possible then. And there is no reason for anyone to do so...just monitor where the plane is going, and make corrections when necessary to ensure you do come to your target position.
From: Doug Brutlag
... I own and have used a (similar) model of the A-5 Pioneer sextant that Fred used on the ill-fated trip. I also own several other models of hand held aviation sextants. I will not claim to be an expert but I can say from experience using them and having face to face discussions with retired navigators who depended on them in their careers, the typical average accuracy for decent navigator was 10-15 miles and on occasion 20 was considered the limit of acceptable (barely). Fred mentions in a letter to PVH Weems an accuracy of 10 miles (approximately). Call it the average --- some did better, some did worse.