Regarding which way to offset when starting the search pattern you would normally turn in the direction to take you to an area you haven't been through yet, if that is not the situation you normally offset into the wind, in this case to the east. But for Noonan, since they knew the wind was out of the east and they expected a smoke trail that would extend off to the west, it would be less likely that they missed to the west than that they missed to the east by overshooting the LOP because they would have had to have been much shorter of the LOP to miss the smoke, so they should offset to the west when returning to commence the modified square search pattern.
I see what you are saying. It would make a lot of sense to look for the smoke rather than the Island itself in this case. My question is did they know that a smoke trail was being laid for them or was that something the Itasca did on it's own? Had they used smoke from a boiler on other occasions? One interesting note I found looking over the logs was a reporter who stated that the smoke trail stretch out for miles and was "low on the water". This is very interesting because we can guess that the range of visibility to the smoke was not improved by the altitude of the smoke.
Yes, Itasca sent a telegram saying they would make smoke during the day and searchlight at night.
Yup, whether they got the last fix at 1623 Z ("partly cloudy") or as late as 1740 Z, Noonan would have planned a sufficient offset to allow for the maximum likely DR error in the leg from that fix to the interception point. That is the whole point of the landfall procedure, to cure any inaccuracy in the DR. So yes, it makes no sense that they didn't find Howland.
Reading over the Waitt Institute re-construction report regarding the 1967 Commemorative Flight.
They were approximately 10--‐12 miles [units not specified] north of Howland Island at the moment they visually acquired the island. Pelllegreno’s account of her thoughts and feelings upon arriving and not seeing Howland, then conducting a protracted search with limited fuel resources, is extremely interesting as a human factors and perational comparison to what may have occurred on AE’s mission. Pellegreno writes a compelling narrative here, one that can not help but evoke a sense of urgency, desperation, and elevated tension. Pellegreno’s flight had the advantage of better navigation equipment, a third set of human eyes, a nearby ship providing good DF bearings, and the luxury of having departed Nauru Island, with a Canton Island destination. With all of these advantages, they nearly missed visually acquiring Howland Island. This account demonstrates the great challenge attempted by Amelia and Fred, and provides a good assessment of the difficulty in visually acquiring tiny Howland Island.
Both Pellegreno's experience and the Waitt video do not match what Earhart would have seen. Pellegreno was flying above the bases of the clouds and a cloud blocked her way so she turned off to the side. Her navigator, Bill Polhemus, said after wards that if they had punched through that cloud they would have ended up right over Howland. The Waitt video was clearly above the bases of the clouds so the clouds also blocked the view of the island until quite close.
Clouds can have two effects on searching for an island. As above, if clouds are below your altitude they can block your view of the island. If you are below the clouds then they cannot block your view but they can make shadows that might be mistaken for the destination producing extra "false islands." The problem caused by this is that they pilot might dart right and left, getting off course, in an effort to evaluate these false destinations. But, if you do your navigation carefully, keeping a good DR as you go to take a closer look at the suspected island, you can then return to your course if it does prove out to be just a shadow and continue your search. Remember, the shadows do not obscure your view of the real island they only add additional targets to check out.
So anything could be possible however AE and FN had one advantage over this flight, the smoke trail.
As a side note, I think that report also solves the question of lighting around Nauru. There is a reference to two 1,000ft cableways on the top of the island, 556 feet above sea level, to permit mining at night. There is also reference from the director of police on the island that the chief radio operator had heard AE say that she saw the lights of Nauru several times. Even though this is the case, I still disagree that the AE spotted the lights of Nauru as this was 2nd hand information gathered after the fact.
I am also a bit troubled as to why they would have stayed on the 157/337 line an hour after having arrived at where they thought Howland was. It makes sense that they would have started a expanding square search pattern as you suggest but this would not be the case if you were flying on the line N and S on the 157/337 LOP an hour after you had arrived. Perhaps there was not plan or knowledge of how to begin the search pattern since they were lost. Perhaps they did search and going back in the line was a last ditch effort as the fuel started to run very low.
The only way I can make sense out of this statement is that they were flying a modified search pattern with longer legs parallel to the LOP and shorter legs perpendicular to it. Earhart might say that she was flying north and south "on the LOP" when on one of these long parallel legs.
Based on assumption that this was their method of search, long North South legs with short offsets, the only thing that makes sense in my mind is that they overshot Howland to the North and were making North / South passes on a 157/337 magnetic course. If as you say they would have traveled sufficiently to handle the worst case DR error, they would have seen the smoke trail if they were on the Western side of Howland. I believe that this was also the opinion of the captain of the Itasca however as far as I can surmise, he did not expect AE and FN to be searching on the Eastern side of Howland, he assumed they must have been short and missed the smoke trail to the West and North.
I also found logs (Jacobson Database) that suggest that Itasca reported 25 NM visibility range at the time. Looking over other documents, it suggests that the CG used a coding scheme that would not have allowed this to be the case so I am a bit confused as to what the actual visibility was on that day. In any case, I am sure FN came up with his own estimate as to the visibility range.
The scale maxed out at "20 NM or more" so you cannot say with certainty that it was 25 NM though it may have been. It is unlikely that it greatly exceeded 25 NM because visibility over the ocean rarely does which is why it was only necessary to have a scale that maxes out at 20 NM or more. Here is a
photo of fairly common good visibility conditions over he ocean.
Based on the Navy Climatic Atlas, in the vicinity of Howland in July, you can expect visibility less than 25 NM 70% of the time; less than 20 NM 60%; less than 15 NM 50% and less than 10 NM 39% of the time. So 40% of the time the visibility will equal or exceed 20 NM. Itasca logged at least 20 NM so there is a 10 % chance that it was more than 20 NM but less than 25 NM and only a 30% chance that it exceeded 25 NM and probably not by a lot more than 25 NM. The clouds depicted in my photo are scattered, about one octa (1/8th coverage). According to the same source, the low cloud coverage in the vicinity of Howland in July is greater than one octa 85% of the time, greater than two octas 62% of the time and greater than five octas, overcast, 25% of the time. Also see
my prior post here. gl