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Author Topic: The flight plan, magnetic course, headwinds.  (Read 411725 times)

Dan Swift

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Re: The flight plan, magnetic course, headwinds.
« Reply #480 on: March 23, 2012, 11:36:51 AM »

Agree with John.  At 1,000 feet and with scattered clouds casting shadows on the water, they could miss Howland very easlily from just a few miles.  Also, not sure about the "we are circling"....could have been "we are listening"...matches up with "but can not hear you" much better in my humble opinion. 
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #481 on: March 23, 2012, 03:42:11 PM »


In order to see shadows you would need to be in the cloudy area, 50NM or so North of Howland. Any further South and the skies were reported to be clear. Also it was clear to the East and to the South.

One question I have not yet answered is at what time that morning would you see shadows from the clouds. The sun would need to be at at some angle to cast the shadows. I have yet to determine at what hour in the morning the sun could cast shadows on the clouds.

If the clouds were at 5,000ft, and you were at 1,000ft, when would you see the first shadows on the sea?
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John Ousterhout

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Re: The flight plan, magnetic course, headwinds.
« Reply #482 on: March 24, 2012, 08:14:21 PM »

As I understand the deck log, the sky above Howland was not completely free of clouds, but "blue sky with detached clouds".  That leaves me with the impression of a very pretty sky with lots of blue showing, and lots of fluffy clouds scattered around.  From the air, those  fluffy clouds are each casting a shadow on the water's surface about the size and shape of Howland island.  Clouds as I've described would not prevent Fred from getting a sun and/or moon shot, would they?  However, without DF, or successful 2-way communication with Itasca, and/or a search pattern with unusually small offsets, they might not have had much chance of finding Howland even with a successful sun/moon shot.  If they flew within a couple miles of Howland, someone would have been likely to hear and see them.  If they were just 5 miles away, they would have been unlikely to be heard or seen.  According to Gary, the navigation uncertainty even with a good sun and moon fix might put them 15 miles from the island, which could be in any direction as far as they can tell.  We don't know what they did after their last transmission, which was believed to have been made from somewhere quite close, as judged by the amplitude of the reception.  Maybe they flew some regular search pattern - do we have any evidence of their knowledge or training of formal search patterns?

See also http://tighar.org/Publications/TTracks/12_2/logjam.html which mentions the deck log interpretation.
Cheers,
JohnO
 
« Last Edit: March 24, 2012, 08:26:26 PM by John Ousterhout »
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #483 on: March 25, 2012, 01:22:20 AM »

Quote from: Gary
But back to the point that I was making, Noonan had clear enough skies to take observations of the sun and moon from at least 40 NM north of Itasca continuing well south of Itasca so would have been able to obtain such sights if they were preceding in the direction of Gardner. These observations, would have shown them that they were closer to Howland than to any other island so that the logical thing for them to do was to fly a search pattern to locate Howland.

Ok, lets run through a scenario. If they ended up North of Howland, say in the clouds just 60NM North of Howland at 19:28GMT ("We are circling"). Since they could not obtain a fix while circling they had to pick a direction to fly so that Fred could take a fix. Since as you say Fred knew that a degree change in the solar azimuth was insignificant, lets run with that idea. So for Fred to take a reading he would have wanted AE to fly the heading 157/337 so he could take an observation correct?
The reason for using the landfall (offset) approach is to know for certain what side of the destination you are on when you intercept the LOP so if he ended up north then it was on purpose and he knew to fly a course of 157° true.
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I believe your theory would require that they would have flown South in order to obtain a fix. I also believe that would require that they knew it was clear to the South.
They didn't have to know that the sky was clear to the south, they would have had to fly the same course regardless.
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But for the sake of argument lets say that this was the case. Say they flew South at 130MPH, they would have been in clear skies in only 5 minutes. How long did you say it requires to take a fix? Lets say 3 readings at 5 minutes per? So say at 19:50GMT they had a fix.
Three minutes for the observation itself plus two more minutes to average the readings and one minute to refer to the precomputed altitude graph, so six minutes for each object observed. You also have to allow two minutes between observations if shifting to a different object. There were only two objects available to observe, the sun and the moon, so only two observations, fourteen minutes total so 1947 Z, close enough, 1950 Z. See example here.
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By this time, the would have flown about 38NM to the South of where they started. Assuming that they were 60NM North originally, this would be roughly 22NM North of Howland. The would have perhaps made a longitudinal adjustment, and would have been on the line by 20:13GMT.  In any case, they should have flown within a very close distance to Howland, well within the visual range as they continued South.

So why did this scenario not pan out?
The fix should not have been in error more than 10 NM in any direction. If they did find that the fix placed them 22 NM from Howland they would have measured the course from there to Howland, turned to a heading to make good that course, allowing for the wind that they had determined already, and flying 22 NM would cause the uncertainty to increase slightly to 12 NM, so they should have seen the island, if everything was working right. Why didn't they, possibly some damage to the octant causing all readings to be off by a fixed amount. It is unlikely that it was off by a great amount or the problem should have been found early in the flight so a smaller fixed error, say 1/4 to 1/2 degree which would produce errors of 15 to 30 NM in each LOP, which could put resulting LOPs off from Howland by up to 40 NM.

When they arrive at where they expected to find the island, and they didn't see it, they should have started a standard search pattern which, if continued long enough, has a high probability of finding the island.

Continuing with this scenario, based on a one-half degree constant error in the octant plus being at the extreme of the uncertainty of an observation, assume the plane is actually 40 NM east and 40 NM north of Howland and the visibility is 20 NM then a standard expanding square search pattern would bring them to Howland after flying 80 NM, if the first leg was flown to the west and then south or to the south and then west; 160 NM if the first leg was to the east then followed by a leg to the south and then a leg to the west or if the first leg was north, then west and then south; or, worst case, after flying 240 NM if the first leg was east, then north, then west, then finally to the south. See attached diagram. The first two legs are twice as long as the visibility, the second two legs are four times visibility, the third two legs are six times visibility, etc.
gl
« Last Edit: March 25, 2012, 01:24:17 AM by Gary LaPook »
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #484 on: March 25, 2012, 06:37:17 AM »

Quote
The reason for using the landfall (offset) approach is to know for certain what side of the destination you are on when you intercept the LOP so if he ended up north then it was on purpose and he knew to fly a course of 157° true.

The only problem that I have with this concept is that there was not enough time to perform the intentional Northern offset. At 17:42GMT, AE reported being 200NM out. I believe that this is the only report where we can roughly surmise their distance from Howland. The "about 100 miles out" was incorrectly associated with the 18:12GMT where AE said she will whistle in the mic at 100 miles out, she never said they are 100 miles out.

The time between the 17:42GMT ("200NM out") and the 19:12GMT ("We must be on you") is 1.5 hours. Calculating the ground speed, this would be about 150MPH. This suggests to me that they came straight in and there was not sufficient time to create a Northern LOP intercept. It would appear that AE thought she could just whistle on the mic and they Itasca would be able to get a fix on her and tell her exactly which direction to travel to reach Howland. As we know this did not turn out as planned. Note that this is probably when they began their decent from 10,000ft down to 1,000ft.

If they did find themselves North of Howland, in the cloud bank, it would seem reasonable that they would run on this line looking for clear skies while searching.

The problem with the expanding square search pattern is that as we discussed previously, by 20:13GMT they were reporting being "on the line 157/337".  To me this suggests that they were either on the original 157/337 heading, actually traveling North and South on the same line over and over for 45 minutes (since 19:28GMT, "We are circling") or they were on a parallel line to the LOP they had established.

If they were on a parallel line this would suggest perhaps they were performing an improvised creeping line search, perhaps using an offset equal to the visibility of 20NM times 2. This would allow them to simultaneously search for Howland and if the opportunity presented itself through clearing skies, FN could shoot the sun. It is possible that the ended up North of Howland, in the cloud bank, and were never able to shoot the sun during the execution of the improvised search pattern. Perhaps the CG was correct in their estimation that they went down anywhere from 337 to 45 true from Howland, up in the cloud bank.

It seems that both the Northern intercept and the expanding square search would be the optimal choices to make it does not appear to be what they had actually done.

It is really unfortunate that AE did not utter another word or two that could have given the CG a clue about her location. It is quite possible she did try to say more and that they either walked over her on the radio or missed her messages altogether by switching back and forth between voice and DF or talking between themselves (Itasca and Howland). That seems to be the case at 17:47GMT and there were probably other incidences as well.
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #485 on: March 25, 2012, 06:49:02 AM »

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As I understand the deck log, the sky above Howland was not completely free of clouds, but "blue sky with detached clouds".

Yes, the log does say that 3/10s of the sky was cloudy. The problem with such terse reports as they are attempting to capture the overall conditions that did not work well, especially on the morning of July 2nd. We know there were heavy clouds to the North and to the West, but little is said about conditions to the East and South. I will need to keep searching but I thought that I had read somewhere that it was clear to the South and to the East.

The statement "Throughout the proceeding night stellar navigating possibilities south and east of Howland and close to Howland had been excellent" would suggest that they skies were much improved to the South and East and perhaps remained that way during the morning hours. It is quite possible that it was actually cloud-less around Howland and to the South and East but unless more statements can be found we cannot be sure. In the Thompson transcript it reports "forenoon" conditions as "smooth seas, good visibility, and an unlimited ceiling".

A reporter on the island that morning stated "We watched the sky hoping to pick the plane out against the white cumulus clouds which were around the horizon as the sun was hot on the white coral". This does suggest that while cumulus clouds were present, they were over on the horizon and not overhead. The hot coral suggests direct prolonged exposure to the sun without intermittent cooling caused by cloudy conditions.
« Last Edit: March 25, 2012, 06:57:45 AM by Heath Smith »
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #486 on: March 28, 2012, 03:26:40 PM »


Quote
I don't get 'solid' like overcast over part of the sky - from these messages, but broken coverage to the WNW, and clearer conditions to east and south.

I think that this is an important detail of the story for attempting to determine where they should not have been. If for example, the visibility was unlimited to the East, and South, this would have allowed AE and FN to spot Howland under ideal conditions (no clouds casting shadows). In theory, with sunshine and no clouds, they might have been able to see out 42 SM to spot Howland. That is quite a distance. Although the ship logs give a 25NM visibility estimate (perhaps even 20NM), that could very well be an underestimate of the actual visibility. Just like the clouds, the visibility ranges were probably very dependent on the direction you were looking.

It seems that most of the witnesses of the day were focused on the North-West and North, where the cloud banks were but say little of conditions elsewhere, at least not that I have been able to find.
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Re: The flight plan, magnetic course, headwinds.
« Reply #487 on: March 29, 2012, 10:42:09 AM »

As to how they could have missed...  Having flown light planes at altitudes >10K for extended periods of time, I have noticed that my landings oft left something to be desired if I was not carrying O2 on board, and always made it a practice to do all my math on the ground prior to flight if at all possible.  To complicate matters, if AE was indeed using the freckle cream mentioned earlier, with its 12% Hg content; Hg is known to produce among others things, symptoms of confusion, agitation and decreased coordination.  As PIC she could have easily decided what direction they were off by, and taken them on a tour in the wrong direction. (If memory serves she had done this on a previous occasion.)  In addition, I find spotting land from low altitudes like 1000' difficult in the tropics because clouds throw shadows that resemble islands, and on certain days the haze can be quite significant (ah la Kennedy off Martha's). CAVU can have a different look when the slant range visibility is significantly reduced because of haze.  Having been forced to rely on instruments over the Everglades on several occasions during what were clear sky conditions, gave me a different attitude to VFR flight. After chasing a few of these phantom islands, coupled with their problems acquiring a signal from Itasca, they could easily have gotten out of sorts and decided to go for "plan b," a small island known to them.  South would have been the preferred direction I believe, as the Japanese were in control of islands to the north and they could be assured of a less than cordial greeting.

As a child I always imagined them ditching in the water and being lost in their small liferaft.  However, as an adult and a pilot, having a plan "b" and heading for an island they thought they could find other than Howland, makes a lot of sense to me.
« Last Edit: March 29, 2012, 10:54:28 AM by Dr James Younghusband, D.C. »
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Jeff Victor Hayden

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Re: The flight plan, magnetic course, headwinds.
« Reply #488 on: March 29, 2012, 02:09:34 PM »

"In addition, I find spotting land from low altitudes like 1000' difficult in the tropics because clouds throw shadows that resemble islands, and on certain days the haze can be quite significant"

Is this video is an example of what you mean Doc?

http://youtu.be/m9c3yZ0xeHw
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #489 on: April 03, 2012, 11:51:41 PM »

I thought maybe the telegram had a typo in it.  A WWII era picture shows a relatively flat island in 1943, as best I can tell - so they must have moved much faster than the 75 years you suggest..
LTM -
For those reading Unbroken, the story of Lou Zamperini, the photo of Nauru in the link above is from a bombing mission on which Zamperini was the bombardier in one of the B-24s on April 22, 1943. His plane made it back to Funafuti with 594 holes in it and had to be junked. One member of his crew was killed and several were wounded.

gl
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #490 on: April 04, 2012, 04:27:41 AM »



If they would have arrived prior to dawn, the lights both on the Itasca and on the Electra would have been much more effective at long distances.
Yep. it's too bad they didn't set the alarm clock to go off about two hours earlier so that they could have arrived in the vicinity of Howland in the dark, it would have been a lot easier to spot the Itasca's spotlight plus Noonan could have gotten stellar fixes all the way to Howland.
gl
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Jeff Victor Hayden

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Re: The flight plan, magnetic course, headwinds.
« Reply #491 on: April 04, 2012, 05:12:06 AM »

I think that's a very good point, arriving at Howland while it was still dark has a lot going for it. Lights from Itasca, illuminated landing strip? Hindsight is a wonderful but useless thought process knowing what we do now.
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #492 on: April 04, 2012, 05:43:40 AM »

Quote
Hindsight is a wonderful but useless thought process knowing what we do now.

True but this was foreseeable as were the many other issues that crop up in the AE story like not making sure that you had a functional radio.

In the end, they surely realized the difficulty of flying directly in to the sun while searching and perhaps shadows on the sea.
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Jeff Victor Hayden

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Re: The flight plan, magnetic course, headwinds.
« Reply #493 on: April 04, 2012, 12:16:39 PM »

Very true Heath, there's an awful lot of 'what the hell were they thinking' in this saga. I get the impression that if they had planned the Lae to Howland leg a bit better and, considered all the things that could possibly go wrong they would have made it.
He who hesitates isn't lost, he just arrives a bit later than those who fail to arrive.
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JNev

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Re: The flight plan, magnetic course, headwinds.
« Reply #494 on: April 06, 2012, 04:36:30 PM »



If they would have arrived prior to dawn, the lights both on the Itasca and on the Electra would have been much more effective at long distances.
Yep. it's too bad they didn't set the alarm clock to go off about two hours earlier so that they could have arrived in the vicinity of Howland in the dark, it would have been a lot easier to spot the Itasca's spotlight plus Noonan could have gotten stellar fixes all the way to Howland.
gl

That's an excellent point, Gary.  Moot, of course, given what happened - but it could have made a huge difference.  One simple alteration in the plan that could have made Howland a blazing beacon - remind me that I'm not flying any oceans in cabin-class twins without you advising. 

A night spotlight from Itasca should have been visible for a very long way, and FN surely would have had many more options than sun and moon - weather permitting, of course.

But if the weather was permitting up to daylight, shouldn't FN have had star shots from which he could have DR'd for only a couple of hours?  Would have given him a good idea of what winds he'd been fighting through the night, and how to correct for the remaining passage.  Does that make you wonder if the weather was not cooperating so well where he was in the last hours before Howland area?

But a bright beacon in the form of a search light on a lonely sea would have been quite a fine thing, for sure - even if compromised to some degree by visibility.  There might have been some good chance of spotting that even through undercast, etc. so long as the plane wasn't really socked-in.

Shoulda-coulda-woulda on AE's and FN's part, I'm afraid.

LTM -
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