TIGHAR
Amelia Earhart Search Forum => Celestial choir => Topic started by: Heath Smith on December 18, 2011, 03:00:52 PM

Can someone please explain to me how it is that the flight from Lae to Howland was planned with a distance of 2556 sm, and the leg from Howland to Honolulu was calculated to 1900 sm?
If you plot out these lines from the two airports to Howland, if correct, you would find that the lines intersect at Howland (at least somewhat close to the Island). They do not.
There seems to be at least a 35+ mile error here somewhere.
If we chose 2456 distance from Lae to Howland (exactly 100 miles shorter than the flight plan indicates), and keep the 1900 to Honolulu intact assuming that it was correct (which may not be the case), these lines make mathematical sense. The only problem is that they intersect about 74 miles North West of Howland in the middle no of where.
It seems at this point that there are a few possibilities here.
1) The plan from Lae to Howland was wrong.
2) The plan from Howland to Honolulu was wrong.
3) Both segments of the plan are wrong.
Am I am missing something here? If so, what is it?
Were the winds aloft included in the Lae to Howland flight plan?
Thanks in advance.

Can someone please explain to me how it is that the flight from Lae to Howland was planned with a distance of 2556 sm, and the leg from Howland to Honolulu was calculated to 1900 sm?
If you plot out these lines from the two airports to Howland, if correct, you would find that the lines intersect at Howland (at least somewhat close to the Island). They do not.
There seems to be at least a 35+ mile error here somewhere.
If we chose 2456 distance from Lae to Howland (exactly 100 miles shorter than the flight plan indicates), and keep the 1900 to Honolulu intact assuming that it was correct (which may not be the case), these lines make mathematical sense. The only problem is that they intersect about 74 miles North West of Howland in the middle no of where.
It seems at this point that there are a few possibilities here.
1) The plan from Lae to Howland was wrong.
2) The plan from Howland to Honolulu was wrong.
3) Both segments of the plan are wrong.
Am I am missing something here? If so, what is it?
Were the winds aloft included in the Lae to Howland flight plan?
Thanks in advance.
Those numbers are correct so there is something wrong with your calculation.
gl

Ok, to test the verification of the values, go to Google Earth and test it yourself.

The mileage from Lae to Howland that I have always seen and remember is 2222nm, which when you convert using 15%, gives 2255 or so.

Heath
When you refer to a flight plan Lae to Howland what plan are you referring to?
I was under the impression that the only plan was the one for the first attempt which was used in reverse for the L to H leg.

I was referring to the below image. I do not have such an image for the Howland to Honolulu leg of the journey but it does exist at Purdue. This is given was 1900 miles in multiple other sources.

Sorry, you were correct, it is the reversed route. In any case, I do not think that the 2556 is correct.

The mileage from Lae to Howland that I have always seen and remember is 2222nm, which when you convert using 15%, gives 2255 or so.
I think Google Earth is pretty accurate in this regard for measuring the distance between two points. You can zoom down in to the old airstrip at Lae then drag the measuring tool all the way to Howland.

The mileage from Lae to Howland that I have always seen and remember is 2222nm, which when you convert using 15%, gives 2255 or so.
Try that math again. 2222 SM X 1.15 SM per NM = 2556 SM.
gl

Did you check the numbers yet Gary?

Google Earth must be way off, at least the measuring tool. I used a different calculator, it says 2561 sm.
This is a point 41 sm past Howland according to Google Earth, this cannot be correct then.

Google Earth must be way off, at least the measuring tool. I used a different calculator, it says 2561 sm.
This is a point 41 sm past Howland according to Google Earth, this cannot be correct then.
I get very good accuracy using the Google Earth measuring tool so you may be doing something wrong.
You can avoid all of this by just doing the trig yourself, just use the standard formula for great circle distance.
Great Circle Distance (NM) = 60 X arc cos[ (sin LAT1 x sin LAT2) + (cos LAT1 x cos LAT2 x cos(difference in longitude))]
To find the difference in longitude, if they both have the same name, east or west, just subtract the smaller from the larger. If of different names then add them together. If the total is greater than 180 degrees then subtract the result from 360 degrees.
The coordinates used by Williams were 6° 47' S, 147° 00' E for Lae and 00° 49' N, 176° 43' W for Howland.
To find the distance in statute miles simply multiply the above result by 1.15.
gl
I have attached Williams' Honolulu to Lae strip chart.

Gary,
I am not sure how I could mess up the measuring tool... I triple checked it. Google Earth is just plain wrong when it comes to the measuring tool. It may have the latitudes and longitudes correct, but the measuring tool is not correct.
Just give it a try, go to the airport at Lae, stretch the measuring tool all the way to Howland and you will see it for yourself.

Gary,
I am not sure how I could mess up the measuring tool... I triple checked it. Google Earth is just plain wrong when it comes to the measuring tool. It may have the latitudes and longitudes correct, but the measuring tool is not correct.
Just give it a try, go to the airport at Lae, stretch the measuring tool all the way to Howland and you will see it for yourself.
I just did. Starting from the end of the Lae runway to the Williams coordinates for Howland I get 2557.58 SM.
gl

As it turns out I was using v.6.0. After upgrading to v6.1, Google Earth reported the correct measure.
Sorry for wasting your time with that goose chase.