Advanced search  
Pages: [1]   Go Down

Author Topic: Line of Position.....157/337 to 158/338  (Read 4691 times)

Randy Conrad

  • TIGHAR member
  • *
  • Posts: 398
Line of Position.....157/337 to 158/338
« on: July 06, 2020, 12:16:30 AM »

Ric,
  Hi! This past weekend I was sitting here wandering what the distance would be if you were on the line 157/337 and the next minute we hear Amelia broadcasting 158/338 according to Betty's notebook. Little did I know you answered that question back in 2010 with the answer of 6 miles. My question is if this be the case...Travelling at 1000 feet from the surface of the water...can you see clearly six miles in either direction? If so...how long would it take to go those six miles? Also, we may or may not have talked about this...but does the Electra have the capability to glide if either engine may fail. If this be the case, how long could she keep the Electra gliding at 1000 ft above the water Love to hear your answers...thanks
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 6098
  • "Do not try. Do or do not. There is no try" Yoda
Re: Line of Position.....157/337 to 158/338
« Reply #1 on: July 06, 2020, 09:13:25 AM »

This past weekend I was sitting here wandering what the distance would be if you were on the line 157/337 and the next minute we hear Amelia broadcasting 158/338 according to Betty's notebook.

Betty did not hear Amelia say 158/338.  Betty heard her say "158 miles."  It would appear to have no relationship to "We are on the line 157 - 337" which are compass directions, not miles.

Little did I know you answered that question back in 2010 with the answer of 6 miles. My question is if this be the case...Travelling at 1000 feet from the surface of the water...can you see clearly six miles in either direction?

Yes, assuming the visibility is good.

If so...how long would it take to go those six miles?

It depends on how fast the airplane is going.  At 130 kts it would take the airplane about 3 minutes to go six nautical miles. At 100 knots it would take about 3.5 minutes.

 
but does the Electra have the capability to glide if either engine may fail. If this be the case, how long could she keep the Electra gliding at 1000 ft above the water

If one engine quits she can continue to fly.  If both engines quit the airplane will glide. I'm not sure what rate of descent the Electra would have at it's best glide speed but I would guess it's about 300 ft/min.  If so, from 1000 feet she would be on the surface in about 3 and a third minutes - but I don't see what this has to do with anything.

However, your mention of "158 mi." in Betty's Notebook got me thinking.  Betty said the reference to 158 miles was among the first things she heard and was part of other things Earhart was saying before Betty started transcribing.  Why would Earhart say 158 miles? We know she was trying to describe where she was but apparently did not know the name of the island.  We also know that she hit the advanced LOP where she thought Howland was, but it wasn't;t there ("We must be on you, but cannot see you.")  We know she then ran north and south on the LOP.
Could 158 miles be the distance she ran south from where she thought Howland should be?  That's something Noonan could calculate.  If they hit the LOP 158 nm from Gardner, they hit it 192 nm southeast of Howland, which puts them right where Bob Brandenburg's propagation model gives Itasca the best chance of hearing Earhart at Strength 5 on 3105.
Logged

Scott C. Mitchell

  • TIGHAR member
  • *
  • Posts: 59
Re: Line of Position.....157/337 to 158/338
« Reply #2 on: July 06, 2020, 10:15:49 AM »

That reasoning sounds plausible.  Question - if they didn't see Howland when they reached the LOP, why would AE still consider that location a relevant data point?  Answer:  if the cloud cover was casting island-impersonating pancake shadows on the ocean surface, then AE might well believe they were still at the right location, right on top of the island, just unable to pick the island out from the cloud shadows.  Therefore, the distance from that location to their castaway site is still relevant to searchers. / Scott #3292
Logged

Randy Conrad

  • TIGHAR member
  • *
  • Posts: 398
Logged

Randy Jacobson

  • TIGHAR member
  • *
  • Posts: 61
Re: Line of Position.....157/337 to 158/338
« Reply #4 on: July 08, 2020, 06:07:57 AM »

The author makes the mistake that when AE broadcasts her position, that is her current position.  I have shown over and over again that this is false.  On her trip from Oakland to Honolulu, where we have good navigational fixes and times, her broadcasts of positions are always latent.  That is, positions given were the last taken prior to her broadcast and are not contemporaneous by anywhere from 15 to 35 minutes late. 

Nearly everyone makes this mistake.  I have written this up and documented it somewhere on the TIGHAR web.

Randy
Logged

Randy Conrad

  • TIGHAR member
  • *
  • Posts: 398
Re: Line of Position.....157/337 to 158/338
« Reply #5 on: July 08, 2020, 03:20:22 PM »

Ric,
 
  Thanks for replying back on my post...but I do have a question in relation to the last part of your post.....   We also know that she hit the advanced LOP where she thought Howland was, but it wasn't;t there ("We must be on you, but cannot see you.")  We know she then ran north and south on the LOP.
Could 158 miles be the distance she ran south from where she thought Howland should be?  That's something Noonan could calculate.  If they hit the LOP 158 nm from Gardner, they hit it 192 nm southeast of Howland, which puts them right where Bob Brandenburg's propagation model gives Itasca the best chance of hearing Earhart at Strength 5 on 3105.


Actually, to be honest you lost me in the transaction. First of all...when you say advanced LOP...are you talking something that Noonan would have to do... say by sextant or map coordinates or whatever. Or is there an instrument on her flying gauges that indicates this. Also, you'll have to draw a diagram in reference to the 158 nm from Gardner and the 192 nm southeast of Howland. Definately, lost me there.
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 6098
  • "Do not try. Do or do not. There is no try" Yoda
Re: Line of Position.....157/337 to 158/338
« Reply #6 on: July 13, 2020, 11:12:04 AM »

First of all...when you say advanced LOP...are you talking something that Noonan would have to do... say by sextant or map coordinates or whatever.

Noonan gets the 157/337 LOP by shooting the sun at sunrise.  He then advances the LOP theoretically so that it falls through Howland Island.  He then measures the distance between where he is now (on the sunrise LOP)  to the advanced LOP and estimate how long it will take to get there.

Also, you'll have to draw a diagram in reference to the 158 nm from Gardner and the 192 nm southeast of Howland. Definately, lost me there.

See below.
Logged
Pages: [1]   Go Up
 

Copyright 2024 by TIGHAR, a non-profit foundation. No portion of the TIGHAR Website may be reproduced by xerographic, photographic, digital or any other means for any purpose. No portion of the TIGHAR Website may be stored in a retrieval system, copied, transmitted or transferred in any form or by any means, whether electronic, mechanical, digital, photographic, magnetic or otherwise, for any purpose without the express, written permission of TIGHAR. All rights reserved.

Contact us at: info@tighar.org • Phone: 610-467-1937 • Membership formwebmaster@tighar.org

Powered by MySQL SMF 2.0.18 | SMF © 2021, Simple Machines Powered by PHP