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[Ric Gillespie]

i have some new thinking about the first section (Lae to nightfall) segment of the flight.
According to Chater, "Arrangements had been made between the plane and Lae station to call at 18 minutes past each hour." Lae heard three reports from Earhart:
• Nothing was heard for the first three hours due to local interference.
• At 04:18Z, four hours and eighteen minutes after departure, Earhart reported "“HEIGHT 7000 FEET SPEED 140 KNOTS” and some remark concerning “LAE” then “EVERYTHING OKAY”.
• At 05:19Z she said, "HEIGHT 10000 FEET POSITION 150.7 east 7.3 south CUMULUS CLOUDS EVERYTHING OKAY”.
• Nothing was heard at 06:18Z.
• At 07:18, she said, "POSITION 4.33 SOUTH 159.7 EAST HEIGHT 8000 FEET OVER CUMULUS CLOUDS WIND 23 KNOTS”

The 04:18Z message contained no intelligible position information.
The position reported in the 05:19Z message, as recorded by Chater, cannot be correct.
The position reported in the 07:18Z message roughly corresponds with the Nukumanu Islands and is on track for Howland.
In the past, we have ignored the 04:18Z message as useless and dismissed the 05:19Z call as obviously incorrect, so we've assumed a straight line course from Lae to the 07:18Z position, as shown in the first map below.

It has been suggested by several researchers the longitude in the 05:19Z message was misheard or mis-transcribed.  Instead of 150.7° E it should be 157° E.  That sounds reasonable. The distance from lae is with the realm of possibility but it puts the airplane well south of course on the coast of Choiseul in the Solomons. Why would they be there?
According to Chater, the weather forecast from Fleet Air Base, Pearl Harbor warned of "dangerous local rain squalls about 300 miles East of Lae."  If the forecast was correct, Earhart may have gone south to find better conditions.  If so, the 04:18 message makes sense.  She did not report her position because she didn't know precisely where she was, but she had a bit of a tailwind and the weather was good so everything was okay.  An hour later, Noonan was able to get a precise location from landmarks on the Choiseul coast - but her report was erroneously recorded.
If that's what happened why did Noonan, in a departure from his usually loose en route navigation habits, then plot a big course correction to get them back on the original track to Howland?  Probably because if he simply plotted a new direct route to Howland they would miss any chance to confirm their progress with USS Ontario whose position was based on the original planned route.
This all makes sense to me but it means the flight covered more miles in the same time than we previously assumed.  The second map below shows the new hypothetical route with [urlhttps://tighar.org/Projects/Earhart/Archives/Documents/Collopy_Letter.html]Collopy's[/url] version of the messages added.
The weather diversion only adds about 130 nm to the trip, which amounts to one hour at the plane's 130 kt cruising speed.  AE expected an 18-hour flight to Howland but it took 19 hours to get to "We must be on you.."  Maybe this is why.

[Andrew M McKenna]

Seems plausible to me.

Wouldn't that also put her an hour behind flying over Numumanu, the Ontario, and the Myrtlebank?  Does that timing also match up with the "ship in sight" report?

amck

[Randy Jacobson]

One of the assumptions that everyone makes is that AE knew all of the weather reports that we know have at our disposal.  When I did my Monte Carlo simulations of her flight, there were two correlated simulations: one with what we absolutely were sure AE received as weather reports before she took off (not what could have been relayed to her once she was in the air) and those weather reports we knew after she took off.  The difference between the two simulations were remarkable.

My question is: At what time did she receive the bad weather 300 miles east of her?  Was it truly received well before she took off (like at least 30 minutes before)?

I like the hypothesis put above, but am, as always, skeptical.

[Ric Gillespie]

Wouldn't that also put her an hour behind flying over Numumanu, the Ontario, and the Myrtlebank?  Does that timing also match up with the "ship in sight" report?

We know it took her 7.3 hours (give or take) to get to the Nukumanu Islands. If she went straight, she covered 735 nm for an average speed of 105 knots.  If she made the suggested diversion she covered 865 nm for an average speed of 119 knots.  I don't see that it has any effect on anything beyond there.
BTW, this suggests the 23 knots of wind was a tailwind, not a headwind as is often claimed.  The airplane was flight-planned at an economical cruise of 130 knots. Her first hour or more is going to be considerably slower than that due to the long slow climb to altitude.  Fours hours after departure she's reporting 140 knots. Seven hours after departure, according to Collopy, she's making 150 knots. 

[Ric Gillespie]

My question is: At what time did she receive the bad weather 300 miles east of her?  Was it truly received well before she took off (like at least 30 minutes before)?

According to Chater:

"At 7.30 a.m., July 1st, the following weather report was received from Tutilla —

"EARHART LAE

FORECAST THURSDAY LAE TO ONTARIO PARTLY CLOUDED RAIN SQUALLS 250 MILES EAST LAE WIND EAST SOUTH EAST TWELVE TO FIFTEEN PERIOD ONTARIO EO LONG ONE SEVEN FIVE PARTLY CLOUDY CUMULUS CLOUDS ABOUT TEN THOUSAND FEET MOSTLY UNLIMITED WIND EAST NORTH EAST EIGHTEEN THENCE TO HOWLAND PARTLY CLOUDY SCATTERED HEAVY SHOWERS WIND EAST NORTH EAST FIFTEEN PERIOD AVOID TOWERING CUMULUS AND SQUALLS BY DETOURS AS CENTRES FREQUENTLY DANGEROUS

FLEET AIR BASE PEARL HARBOUR".

[Note, the above forecast was made more than 24 hours before Earhart's departure on July 2]

"At 10:00 a.m. the machine was taken off, the actual take-off being satisfactory for a heavily loaded machine – the run taken was approximately 850 yards.

As the machine was leaving the ground the following weather reports were received at the Lae Wireless Station –

"EARHART LAE

ACCURATE FORECAST DIFFICULT ACCOUNT LACK OF REPORTS YOUR VICINITY PERIOD CONDITIONS APPEAR GENERALLY AVERAGE OVER ROUTE NO MAJOR STORM APPARENTLY PARTLY CLOUDY WITH DANGEROUS LOCAL RAIN SQUALLS ABOUT 300 MILES EAST OF LAE AND SCATTERED HEAVY SHOWERS REMAINDER OF ROUTE PERIOD WIND EAST SOUTH EAST ABOUT TWENTY FIVE KNOTS TO ONTARIO THEN EAST TO EAST NORTH EAST ABOUT 20 KNOT TO HOWLAND

FLEET BASE PEARL HARBOUR

and

BARO 29.898 THEMO 83 WIND EASTERLY 3 CLOUDY BUT FINE CLOUDS CI CI STR CU CUMI MOVING FROM EASTERLY DIRECTION SEA SMOOTH. NARU 8 AM UPPER AIR OBSERVATION 2000 FEET NINETY DEGREES 14 MPH 4000 FEET NINETY DEGREES 12 MPH 7500 FEET NINETY DEGREES 24 MPH".

These reports were then transmitted by the Lae Operator by radio telephone during each hourly transmission time arranged by Miss Earhart until 5.20 p.m. local time."

We don't know whether Earhart ever received the forecasts Lae transmitted, but it really doesn't matter.  As any pilot can tell you, the only weather that counts is what's outside the window. If the forecast was correct, when she got about 300 miles out she was presented with towering squalls it would be foolish to mess with.

[Christian Stock]

In the context of garbly radio talk, 157.7 makes as much sense as 157. Either way, big course change to the northeast to get back on track to hopefully see the picket ship.

[Eric Sussman]

Ric,
 
So let's assume the reason for taking 19 hours flight time to reach the point "We must be on you" is your revised flight path, how would that impact AE's flight decisions from that point on.  This would mean AE was not searching the area for Howland for an hour in frustration, but was just arriving there. Do her known actions and transmissions from this point on take on a different cast?

Eric

[Ric Gillespie]

Do her known actions and transmissions from this point on take on a different cast.

No. it has always been the case that she reached where she thought Howland should be ("We must be on you...") 19 hours after departure - an hour longer than she originally anticipated. She was worried.  She was an hour late, no island in sight, unable to establish radio communication, and starting to burn into her fuel reserve - hence, but fuel is running low.
Other researchers, most notably Elgen Long, have attributed the delay to headwinds. This new route provides an alternative explanation for the delay.

[Randy Jacobson]

Do her known actions and transmissions from this point on take on a different cast.

No. it has always been the case that she reached where she thought Howland should be ("We must be on you...") 19 hours after departure - an hour longer than she originally anticipated. She was worried.  She was an hour late, no island in sight, unable to establish radio communication, and starting to burn into her fuel reserve - hence, but fuel is running low.
Other researchers, most notably Elgen Long, have attributed the delay to headwinds. This new route provides an alternative explanation for the delay.

My Monte Carlo analysis of her flight (which assumed the Nikumanu Island start point) using known winds during the flight (headwinds) put her near the LOP but significantly south due to her over-correction of projected winds vice actual (speed and direction).  She had to have headwinds along most of the route: that is due to the equatorial steering currents of air (east to west near the equator).  As one deviates from the equator (actually, the Intertropical Convergence Zone), winds shift from due east (westerly winds) to WSW or WNW, depending upon north or south of the equator. 

I don't want to give anyone the impression that AE had tailwinds or no headwinds during the flight. 

[Ric Gillespie]

My Monte Carlo analysis of her flight (which assumed the Nikumanu Island start point) using known winds during the flight (headwinds)

What known winds?  To my knowledge we have zero information about what winds the flight actually experienced other than Earhart's comment "wind 23 knots" with no mention of wind direction.

put her near the LOP but significantly south due to her over-correction of projected winds vice actual (speed and direction).

I agree that is probably what put her south, but it's speculation - not fact.

  She had to have headwinds along most of the route: that is due to the equatorial steering currents of air (east to west near the equator).  As one deviates from the equator (actually, the Intertropical Convergence Zone), winds shift from due east (westerly winds) to WSW or WNW, depending upon north or south of the equator.

Yes, the prevailing winds south of the Intertropical Convergence Zone tend to be from the East, but "tend to be" is not "had to have."

I don't want to give anyone the impression that AE had tailwinds or no headwinds during the flight.

Neither do I.  We know roughly when she left Lae and we know roughly when she got to the LOP.  If we take her word for it, we know roughly where she was at one point during the flight (Nukumanu).  We also have a rough idea of the airplane's capability, assuming she followed Kelly Johnson's recommendations.
Any conclusions we draw about winds from a Monte Carlo simulation should be prefaced with, "Odds are...".
There's a reason it's called Monte Carlo.

[Jon Romig]

Sorry for the dumb question - I think this is 9th grade algebra (50+ years ago!):

Would 19 hours of straight-path flying (thus there must have been headwinds to fight) have consumed more or less fuel than 19 hours flying over a longer distance but with no or lower headwinds (thus a lower average speed over the ground)?

Thanks for your patience,

Jon

[Andrew M McKenna]

Jon

19 hours of flying is 19 hours.  If the power settings and mixture were the same, the fuel burn would be the same, you just wouldn't get as far in the time flown.

There is some speculation that to counter a headwind, power could have been increased as a measure to increase speed and arrive at the destination around the intended time.  The strategy there is to offset the increased fuel burn by the decreased time. 

Hard to know if AE used this strategy.  All we can do is figure an average, assuming she actually and accurately made it to the LOP when she said she did, and even then we don't know exactly where on the LOP she was.

Someone will no doubt have a better explanation, but those are my initial thoughts.

A McKenna

[Ric Gillespie]

There is some speculation that to counter a headwind, power could have been increased as a measure to increase speed and arrive at the destination around the intended time.  The strategy there is to offset the increased fuel burn by the decreased time. 

Hard to know if AE used this strategy.

It's hard to know why she would do that. You can bump up the power to fight a headwind but only if you have the luxury of having plenty of fuel. It's an economic decision to accept a higher cost to get there sooner, so you need a reason to get there sooner.  For NR16020, the throttles, props, mixture settings and altitudes recommended by Kelly Johnson delivered the best fuel economy and a true airspeed of 130 knots.  The airplane will cover the most distance at those settings.  If she encounters headwinds, it will take longer to get there but she'll still get there unless the headwinds are so strong that she'll run out of fuel first.  She can go faster by increasing power  but drag increases as the square of speed.  Going a little bit faster takes a whole lot more power and burns a whole lot more gas. If she doesn't have enough gas to get there at her best fuel economy power settings she can't fix the problem by increasing power - she'll just run out of fuel sooner.  If she can't get there at best economical cruise she has no choice but to turn back - unless she has passed the point of no return, in which case all she can do is maintain best economy cruise and hope for the best. 

[James Champion]

Amelia had no incentive to burn extra fuel.  Amelia would certainly not want to risk burning into her 50 gallons of 100 octane additional reserve fuel she carried in her 102 gallon tank as she would want this for extra takeoff power from Howland. At Lae and at and again at Howland only 87 octane was available and was used for cruise flight. She would not be able to replenish the 100 octane until Hawaii.

[Simon Ellwood]

Ric said:-
>>It's an economic decision to accept a higher cost to get there sooner, so you need a reason to get there sooner.  For NR16020, the throttles, props, mixture settings and altitudes recommended by Kelly Johnson delivered the best fuel economy and a true airspeed of 130 knots.  The airplane will cover the most distance at those settings.

I think these recommended figures give a maximum endurance (time based), rather than the maximum distance, although for the low to moderate headwinds here it makes little difference to the fuel economy for distance - so the point is moot.

For high headwinds however - where the headwind is a significant portion of the airspeed, there is a case for a speed increase, as the ground speed increase may exceed the drag/power/fuel usage squared increase.