Highlights From the Forum March 4 through 10, 2001 |
Contents:
(click on the number to go directly to that message) |
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FN's Navigation | Alan Caldwell | |
Must Be On You ... | Chris Kennedy | |
Re: FN's Navigation | Bob Brandenburg | |
200 or 100? | Bob Brandenburg | |
Re: FN's Navigation | Chris Kennedy | |
Re: FN's Navigation | Alan Caldwell | |
Re: 200 or 100? | Alan Caldwell | |
Re: FN's Navigation | Bob Sherman | |
Still Suicidal? | Chris Kennedy | |
LOP DR Comparison | Tom MM | |
Comprehending the Final Hours | Don Neumann | |
LOP --- Yet Again! | Dennis McGee | |
LOP DR Comparison | Tom MM | |
Octant vs. Sextant | Bob Brandenburg | |
Re: LOP DR Comparison | Marty Moleski | |
Re: LOP DR Comparison | Herman De Wulf | |
Re: LOP DR Comparison | Tomm MM |
This line of postings concerning latitude is getting pretty interesting. Indeed, why would we, today, know anything more about sun, moon, star and planet positions on the morning of July 2nd than Noonan did in 1937? IF Noonan thought he could determine latitude that morning before setting out, this would make the radio direction finding much less important, and perhaps explains some of the cavalier attitude to making sure it was working o.k. In the larger scale of things, if he were able to get a latitude reading, it makes one wonder what went wrong. The really horrifying thought is that they flew right over Howland, or in theoretical visual range from both plane and ship, but neither saw the other nor did Earhart see Howland. Big sky, big sea, small plane, small island and loud surf. I have been at sea, and can well imagine this happening. That Earhart transmission "we must be on you but can't see you", has long been the one I have found most important and troubling. The "must" conveys almost a sense of disbelief that they weren't seeing island and ship. We've discussed before the mapping error of Howland's position, yet for reasons Ric explained I believe we feel confident that AE and FN had been told, even though the charts hadn't been fixed. I wonder if we're wrong? --Chris Kennedy From Ric I'm less troubled than you are by Earhart's choice of words. How many times have you searched a counter top for your car keys and said, "They MUST be right here." forgetting that you left them in your jacket pocket. Earhart's phraseology indicates only her own expectation. We don't know that Noonan shared her level of conviction. |
Chris Kennedy makes a good point. If Noonan got a moon shot near meridian passage, he could have worked out his latitude. If he did, he would have known which direction to turn on the LOP. And, by the way, he would have known how far he was from Howland. That he didn't get there and went to Gardner instead suggests that he didn't get that moon shot.
Bob Brandenburg |
When I omitted Venus as a candidate for a three-body fix, I neglected to mention that Venus would be close to the Sun's azimuth and probably would have been hard to see in the morning sun. But it is interesting to speculate that Noonan could have used Venus for an LOP before sunrise, and then shot another LOP when the sun came up. At 1744 GMT, when Noonan was about 200 miles out, Venus was at Hc 41 degrees and Zn 69 degrees, and the Sun was at Hc -4 degrees, or just below the horizon, and Noonan was in nautical twilight. But if he had shot Venus a little earlier, the Zn would have been closer to dead-ahead and FN's LOP would have been somewhere around 340/160. But the timing and apparent speed discrepancy between the "200 miles out" message and the "100 miles out" message suggest that the "200 miles out" estimate was based on a DR and the "100 miles" estimate was based on an LOP after sunrise.
Bob From Ric Everyone agrees that the "200 miles out" report at 17:45 GMT and the "100 miles out" a half hour later at 18:15 GMT can not both be correct. Earhart's "We must be on you.." at 19:12 would seem to indicate that, by that time, they believed that they had reached the advanced LOP, had had time to look around enough to be convinced that there was a problem, and make a radio transmission pretty much on the quarter-past-the-hour schedule. For the sake of argument, let's say they hit (or thought they hit) the advanced LOP at 19:00. Let's also say, just for the heck of it, that they really were on the LOP that passed through Howland. We should apply a similar standard to the earlier transmissions and say that they represent a position estimate that was valid about 15 minutes before the message was actually sent. So --- if they were "200 miles out" at 17:30 and were on the LOP at 19:00, they covered 200 miles in 90 minutes (we're talking ballpark here) for a groundspeed of 133 kts (assuming that the distances are provided to AE by Noonan who speaks in nautical miles). That seems like a fairly reasonable speed given that the airplane cruises at 130 kts. They probably have a bit of a headwind but they're also probably coming downhill for much of that time, descending to 1,000 feet. If they're "100 miles out" at 18:00 and on the LOP at 19:00, they have covered those 100 miles in 60 minutes, for a groundspeed of 100 kts. For that to make sense you have to assume that the descent was already accomplished and that the cruising speed down low was more like 115 kts (into, say, a 15 kt headwind). Neither of those assumptions seems outlandish. In other words, in very general terms, either the 200 or 100 estimate could be correct, but not both. Bob's speculation that the earlier estimate was the rougher one makes sense, but it argues against recent speculation that Noonan got a predawn whack at Venus.
LTM, |
Alternatively, could the failure to reach Howland also suggest that Noonan did get his moon shot, but that the error in Howland's position on charts was not known to Noonan? I guess what I am suggesting, here, is that we have said before (in relation to the fuel consumption work) that contra Long's theory, there is nothing to suggest that the flight used more fuel than was planned. It also seems that the "we must be on you..." transmission indicates that they thought they should see the ship/island, even though we know they hadn't received a radio direction. I am just reading the words Earhart transmitted and giving them their plain meaning. So, it would appear that they weren't relying upon the radio direction to find the island as they thought they had "found" it. I know it seems amazing, but perhaps they didn't know of the error, got the moon shot, and "found" Howland where the chart said, but beyond visual range of where Howland actually was. I apologize for being such a stickler on this, but I am slowly seeing the following analysis develop:
--Chris Kennedy From Ric No, the presumed location of the "target" has nothing to do with what LOP you get. That is dictated by what heavenly bodies you can see and where they are. All of this speculation about Noonan's supposed ability to navigate accurately to a tiny island without help from Radio Direction Finding ignores the simple historical fact that it was reliable DF that made island to island flight practical. We can sit in our chairs and make all kinds of pronouncements about what Noonan "should have" been able to do but the truth is that finding a small, isolated island after a long overwater flight without some kind of eletronic guideance was, and still is, considered impractical and extremely dangerous. |
Ric wrote:
> We can sit in our chairs and make all kinds of That's a good summation of what AE and FN were trying to do. Let me make the LOP stuff a bit clearer. When we say the 157/337 LOP gave Noonan his longitude but not his latitude we are not being accurate. It will NOT give FN his longitude. Only if he knew his aproximate latitude would he then get his longitude. Why is that? Well because that LOP is at an angle to east/west and only if he had a north/south LOP (360/180) would he actually have his longitude without other aid. To get his latitude unaided by other LOPs he would have to get an east/west LOP (090/270). Let's say he only shot Venus or only shot the sun. He would NOT know his latitude and thus not know his position on the LOP but he could still plot it through Howland assuming he knew where Howland was. If he had but one more body to shoot he would have plotted two LOPs on his chart and they would have looked like an "X" but not like a cross. One pair of ends would have been much closer together than the other two. Where they intersect is where his position is supposed to be. The only reason for shooting THREE star LOPs is to reduce the possible error. In that case three lines would cross on the chart and the plane's position should be somewhere in the (hopefully) tiny triangle formed where all three intersect. That usually is a 2 to 3 mile space if all conditions are good.
Alan |
Bob Brandenburg writes: > But the timing
and apparent speed discrepancy between the "200 miles out" I'm more inclined to believe the 157/337 LOP was a precomp. Possibly not but I think so. Preplanning the celestial would have also preplanned the infamous "Plan B". My nav precomped the whole flight but I don't know whether that was Noonan's practice. Even if he didn't do it prior to flight he most likely did so in the air. I can not think of a good rational reason NOT to shoot Venus. FN NEEDED the information Venus could provide. I have no way of knowing whether 200 miles out was based on DR or on fixes but if you remember the "100 miles out" was suspect as it was clearly added later as evidenced by the type misalignment. I never convinced myself of whether she was saying she was 100 miles out or that she would whistle when she was 100 miles out. Let me also remind everyone that the fact they missed Howland is not NECESSARILY because they navigated in error. It could have been because Howland wasn't where they had it plotted BUT it could be they had Howland plotted correctly AND navigated accurately and just flat couldn't see the island for scattered CU.
Alan |
Chris Kennedy wrote:
>This line of postings concerning latitude is getting pretty interesting. Except for small refinements, we don't.
>If Noonan thought he could determine latitude that morning before With the state of the art, & Fred's handicap of not having a nav station , astro dome, and radio operator as he did with the 'Clippers', finding a one mile island when a fix within 5 miles under ideal conditions was the best he could expect, is not a formula for success every time. Under perfect conditions he could find Howland. But what if they were not ideal? GPS working perfectly will be accurate within a few meters! But what if there is a glitch of some kind? Ever heard of something like that happening? DF of some kind, either she does it or they do it, was the back up. Why else was the Itasca there?
> .. perhaps explains some of the cavalier attitude to making sure it Delaying the t.o. from Lae for a day or two to get the radio time signals was far from a cavalier attitude. Fred was aware of the job ahead. More likely he was assured by those in charge of the trip that all would be taken care of, thus he needed only to get within range; and I think he did. >... if he were able to get a latitude reading... Latitude or longitude are only lops. At least two intersecting lops are required to know where one is. Seeing and 'shooting' a body doesn't mean an lop within one mile. Time -- seconds -- is of the essence with some shots. With Polaris the pole star [perfect latitude with just one shot] even a minute off is seldom of any consequence. But near the equator Polaris is not visible. With the sun a minute could be miles. Low altitude shots have a correction, the sun & moon have semi-diameter correction [the center is not easily determined] & the moon has a parallax error due to its nearness. Anything other than three bright stars, high in the sky, about 120 degrees apart in azimuth, shot from smooooth air, will have a number of potential errors to contend with. > .... makes one wonder what went wrong... There were many things that could go wrong; the list is long. RCS |
No, the subject title doesn't describe me, but just a facet of the recent postings on latitude/longitude that have added a new dimension to the idea that it would have been suicidal for AE and FN not to have headed southeast down the LOP toward Howland or to islands beyond. Up until recently we had been running under the assumption that the flight didn't know whether it was north or south of Howland when turning onto the LOP. Regardless, if you ran southeast on the LOP you would hit either Howland or other islands, so it's suicidal not to do that and keep running north and south. Makes sense. Now, the issue has come up of whether FN would have been able to compute his latitude. This is new. Cutting to the bottom line, it seems from all I've read that it could well have been possible for FN to have gotten a latitude fix (none of the celestial experts has come out with the flat conclusion that the heavenly bodies weren't there for FN to shoot), but that even if he were able to get a fix AND this were an accurate fix it would still not pinpoint Howland, but simply reduce the area in which the island lay. Indeed, it appears that it might reduce the area considerably. Of course, anything which reduces the area in which your target lies would, I suspect, tend to influence your decision whether to search for it. While my navigator is telling me that I can run southeast along the LOP and run by a number of islands on which to land, my navigator is also responsible for getting me to my primary target (Howland), and I'm not seeing it, even though he's telling me enough so that I can say "we must be on you but cannot see you". If I am going to believe him and fly to the southeast, then I should also believe him that we are near to our primary target even though I don't see it (again, I have reported to the ship that "we must be on you..." so I believe what I'm being told) . I do have four hours or so of fuel left, maybe more, to fly the distance, but how can I be sure that I am not going to have to search a bit for these islands if I fly beyond my primary target? After all, none of these islands along the LOP is Australia. Of course, none of these other islands has a landing strip and fuel and a ship standing by. In other words, given that my navigator says we must be close to Howland, am I better off using what time I have left (which may be considerable) to run a search pattern for my primary target and see if I can contact that damned ship for them to send a signal, and isn't it really suicidal heading permanently southeast? --Chris Kennedy From Ric Nothing has changed. For all the speculation about the moon, I've heard no experienced navigator claim that a 30 degree cut would give Noonan a reliable latitude. Once he reaches the advanced LOP he clearly does not know whether he is north or south of Howland (else why run north and south?). Ultimately his only safe course of action is to run southeastward on the LOP. |
Finding 1937 flight era data on DR vs actual track is tough, but looking at the data on the Research CD for the Oakland -- Honolulu flight gives some insight in what to expect when running down an LOP via DR. I understand that the software that Randy used did some smoothing, but I think the overall result might be better than the raw data with its inherant errors. I've picked out the longer legs, since anything less than about an hour's flight time (~130 NM) is bound to be suspect. Here is how things look when comparing DR to Actual track. I've added a column for extrapolating the error to an arbitrary 350 NM, since the distance run down the 157 LOP could be more or less than that. Still it is illustrative.
If we assume that miraculously enough they hit the 157-337 LOP perfectly, that they never strayed at all from that exact LOP in the turning and running N-S for an hour, and if we assume that Howland and Niku lie exactly on a 157-337 LOP (they are slightly off), then how well must they be able to DR down that LOP to get within 10 NM sight distance of Niku after leaving the Howland area? They would need to achieve an average angular accuracy in flight of less than 1.6 degrees difference from their DR. At 15 NM sight distance that accuracy would have to be better than 2.5 degrees. That includes all sources of error - pilot, instruments, and wind. Virtually any error in hitting the LOP or subsequent search maneuvers would further reduce their prospects of nailing Niku. Can someone explain to me how an Electra era aircraft w/o RDF and apparently lacking adequate technology to estimate wind drift would attempt this? (Amateur experts will be awarded extra points). TOM MM From Ric Your analysis seems to indicate that an airplane can't DR anywhere very far without wandering significantly off track. If you don't like 350 miles try 3700. I guess "Lucky Lindy" really was phenomenally lucky. You seem to draw the conclusion that running down the LOP was an irrational act. Certainly the U.S. Navy "experts" in 1937 did not share that view when they tasked the USS Colorado to search southeastward along the LOP. Nobody at the time articulated an opinion that the flight may have flown some kind of organized search pattern until it ran out of gas or flung itself blindly toward the "catcher's mitt" of the Phoenix Group. I think this points up a danger in historical research. It's always tempting to try to figure out what the most sensible thing to do would be and then ascribe that action to someone in the past. But the question is never what people SHOULD have done. It's what people DID do in the context of the times. Your question is not whether Noonan could have run down the LOP and hit Gardner (clearly that was possible), but whether he would have seen it as a rational course of action. We, of course, don't know what Noonan actually did in this situation, but we do know what other experienced aviation people operating in that same context reasoned that he would do. I submit that their opinion is inherently superior to ours.
LTM, |
Alan Caldwell wrote: >...I'm sure they
would have assumed when they didn't show up a search Therein seems to lie the single most difficult aspect of the final hours of the flight to comprehend. In the final few messages actually received by the Itasca (no record, of course, of any messages actually sent by AE but not received by Itasca...or anyone else), we learn the...'gas is running low'...'we must be on you'...'we are _______(circling, listening...etc.)'...'we are running North & South on LOP...', however not a single clue as to their further intentions, should Howland not suddenly appear in front of the windscreen or they are unable to raise Itasca on the radio or obtain a DF bearing. Perhaps we may speculate that at that point-in-time, the full realization of their plight did not actually occupy their immediate thinking, obsessed as they were with the objective of actually seeing Howland &/or securing two-way radio communication &/or DF bearing with Itasca. Maybe they were convinced they still had sufficient Fuel/time to search-out illusive Howland Island & they were not prepared to admit to themselves it was now time to consider & to convey to, the only source of rescue known to them at that time, Itasca, they were seeking an alternate landfall. Perhaps the change to the daytime radio frequency, (notice of which was conveyed to Itasca) was the key, missing link, that ultimately caused them to literally 'disappear' from the airwaves at the most crucial stage of the flight, while Itasca's skipper made his decision to pursue a preemptory search to the NW , in the opposite direction from the flight, if we presume they headed SE on the LOP. To paraphrase an old motion picture title... Fate sometimes is indeed the Hunter...! Don Neumann From Ric I wish, I wish, I wish we could get away from this notion that a decision was ever made to seek out an alternate destination. Earhart and Noonan were (I believe) trying to find Howland -- period -- full stop -- end of sentence. At no point did they say, "Screw this. Let's go someplace else." There was no "Plan B." Running southeastward on the LOP was not the only course of action that might get them to Howland. They could also fly northwestward. But there were other islands to the southeast of Howland that could serve as landmarks to tell them how to get to Howland, so southeast was the best direction to fly. Finally figuring out where they were, but without enough fuel to get to Howland, was an almost worst-case scenario. The only thing less desirable was having to land in the ocean. I suspect that only when an island appeared in the windshield that obviously was neither Howland nor Baker did they fully accept that they were going to have to terminate the flight at someplace other than their intended destination.
LTM, |
Ric said:
I take this to mean that they hit the LOP, didn't see Howland, and immediately turned right to head down the LOP, expecting to find Howland but also knowing that there IS land SOMEWHERE along that line. I interpret the comments to mean AE/FN did not initiate an "organized" search (i.e. expanding box patterns etc.) for Howland once they hit the LOP. Under this scenario it would've taken them less than 30 minutes (65+/- miles) to realize that something was seriously wrong and had two options: A, continue southeast and eventually hit some island; or B, do a 180 and fly for 30 minutes back to where they hit the LOP and continue northwest looking for Howland. Option B really hugs the big one considering the fuel situation. I am really baffled at why people have a hard time accepting this. I think Occam's Razor applies here. LTM, who's had a close shave or two also From Ric You have somewhat misinterpreted what I said. I do not think that they "immediately turned right to head down the LOP." I suspect that they explored northwestward along the line for a some period of time dictated by their perceived fuel situation before reversing course and proceeding southeastward. That would makes sense and would explain AE's "running on north and south line" comment. |
>If you don't like 350 miles try 3700. I guess "Lucky Lindy" really was
phenomenally lucky. If "Lucky Lindy" had DR'd 3,700 miles to a tiny remote island in the Pacific, he would be called "Looney Lindy". Hitting the European continent is somewhat easier, but as AE herself found, you can miss by an Ireland or so. Yes, in my own ignorant amateurish way, I think that there were other good choices. It is not that I think the 157-337 Niku idea is irrational at all --- what bothers me is TIGHAR's position that anything ELSE is irrational, suicidal, whatever. In fact, I believe that there were several very rational choices, none of them really good. Like many forumites, I parcel my bets out a percentage here, a percentage there. __% crashed at sea, __% Niku, __% other Phoenix, __% Gilberts. 0.00001% Other. TOM MM From Ric My point about Lindbergh is that he, in fact, hit his targeted landfall on the coast of Ireland within something like three miles. Luck really is the only way to account for that. Parceling your bets does have the advantage of guaranteeing that you will be correct, to some degree, when and if the answer is known. But if you're actually going to do something about finding the answer you have to pick a hypothesis and test it. I can't put x% of the team searching the ocean bottom and x% searching the Gilberts and x% checking out the other islands of the Phoenix Group. I have to go where the evidence points, and right now it looks to me like it all points to Niku.
LTM, |
Tom MM writes:
> One possible use for FN's marine sextant "preventer" could have been sights It's instructive to consider whether such opportunities existed. We know that FN was at 1,000 feet under a cumulus cloud deck with 50 percent coverage and bottoms at about 2,700 feet. We also know that in order to get a sun line early enough to estimate his distance from the 157/337 LOP through Howland, FN needed to get the sight soon after sunrise. From his altitude, FN was viewing the bottoms of the clouds at a grazing angle on the order of 2 degrees or less. At such a shallow viewing angle, the cloud bottoms appear to merge into a solid mass and 50 percent coverage looks like 100 percent. Hence, no near-sunrise sight opportunities. But what about opportunities to shoot the sun through gaps between clouds when the sight angle was steeper? Since cumulous clouds have random vertical development on the order of hundreds to thousands of feet, the gaps between clouds in FN's neighborhood were like silos. He could see the sun only if it was above the rim of a gap above him. Since the sun's declination was about 23 degrees north and FN was near the equator, the sun could easily be obscured by even moderate cloud thickness. FN's problem gets even worse when we consider his speed. At 115 knots, he was moving across the bottoms of cloud gaps at about 11,600 feet per minute. If the gaps averaged 1,000 feet in diameter, then FN's average time under a cloud gap was about 5 seconds, during which he would have to acquire the sun in his sextant's viewfinder and shoot the sight. Not much of an opportunity. The cold, hard reality is that having gone below the cloud deck, FN lost any realistic opportunity for a sun sight, either with the bubble octant or the sextant.
Bob, |
Ric wrote:
> My point about Lindbergh is that he, in fact, hit his targeted landfall on I've heard somewhere--probably on this Forum--that Lindbergh taught dead reckoning to military pilots. I can't track down the quotation, but in his opening remarks he is said to have said something like, "The only thing wrong with dead reckoning is the name." I've got another very, very fuzzy recollection of the autobiography of a pilot and sailor who pioneered and taught navigation techniques to be used by pilots in WW II. They needed to have a system for keeping track of how much their evasive maneuvers had thrown them off track in order to find their targets and then get home again. This guy was nearly killed flying out of a harbor in Asia (Hong Kong? Singapore?) when his seaplane clipped some telephone or power lines that crossed part of his flight path. His story made me want to more about navigating. Haven't followed up on it so far, except for reading Longitude. Marty From Ric Lindbergh, as a civilian consultant, advised Army pilots in the Pacific during WWII primarily on fuel conservation techniques, but given his vast navigational experience he probably talked about that too. |
Ric wrote: > My point about Lindbergh is that he, in fact, hit his targeted landfall
on Even Lucky Lindy agreed to that. In his autobiography he wrote somewhere (I can look it up if you like) that he calculated his course without taking into account wind corrections since he had no information whatever on weather or the wind en route. It so happened that this was his best bet for he did hit upon Ireland within something like three miles from his estimated point. I remember he wrote that before he took off he was invited by navy officers to come and explain his navigation. He did and he wrote they were impressed because they didn't know how they would have solved his problem under the given circumstances (this being 1927 technology and weather information en route). Surely FN must have known about Lindbergh's technique too. Charles Lindbergh carefully calculated his route and sticked to his calculated headings. Being the good navigator he was I'm sure Fred Noonan prepared the flight to Howland just as carefully and also sticked to his figures. The one advantage he had over LIndbergh was that AE flew the airplane and he could check on the progress of the flight shooting celestial bodies. I also feel confident that he wouldn't have corrected course too often. He was pretty confident to be able to navigate to within DF range of Howland. Somebody on this forum wrote that on long haul flights over water he used to take altitude changes en route as an indication of changes outside air pressure and... not correct for wind but keep on course. Eventually they would get to where they intended to but faster than the guys who did correct for wind. Are we sure that FN hadn't learned this too ? So if someone takes out his slide rule and calculates FN's DR route to Howland, where would AE/FN eventually end up ? On the LOP and the Itasca DF signal would tell them which way Howland was. But that's where everything went wrong. |
As much as I feel compelled to yank on the TIGHAR'S tail from time to time, I do want to make it clear that I respect and appreciate your efforts to resolve the Earhart mystery. I wish more groups were out there pursuing their theories because ultimately that would lead to the larger goal of finding the remains of the aircraft and closing the books on this - whoever is right. After a couple of years on the forum, I will offer this honest and frank thought. If TIGHAR was less absolute, as in "this is the way and the light" about their own hypothesis, and a bit more neutral about other hypotheses, I believe it would add significantly to their credibility and base of support. Free advice --- and of course, worth every penny.
Back to the battle lines, From Ric Thanks Tom. I appreciate your thoughts. You, and others, may find this hard to believe, but I regularly indulge an almost perverse desire to convince myself that the whole panoply of Niku evidence is an illusion that can be explained away. When some artifact that we've been excited about gets eliminated, usually though our own research, its almost a relief (I told it was perverse). Likewise, I have searched quite eagerly for someone who can make a compelling case for crashed-at-sea or even Japanee-man-take-rady-frier-Saipan but, so far, without success. I was genuinely disappointed in Elgen Long's book. After so many years of him being seen by many as the voice of reason in the Earhart controversy, his long-awaited treatise on why Earhart went down at sea was -- well -- sad. Time and time again we've had gunslingers ride into our virtual town here on the forum. They call us out into the street and we let them draw and shoot. So far all we've seen are little flags that say "Bang!"
LTM, |
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