It is instructive
to investigate the various procedures for radio, navigation, and piloting
for the best documented segment of Earhart’s World Flight: the crossing
the Eastern Pacific from Oakland to Honolulu on March 17, 1937. This first
attempt at the around the world flight provides many clues and insights
into later flight segments. Much careful planning by William Miller, on
“loan” from the Bureau of Air Commerce, well documented and
distributed to the US Navy and US Coast Guard, was carried over to the second
attempt. Unfortunately, Bill Miller was assigned to investigate the potential
for air mail routes to New Zealand shortly after Earhart’s abortive
crash take-off in Honolulu, and was unavailable to provide the detailed
planning necessary for a successful second attempt for the world flight.
George Putnam took over the logistics and planning, but appeared not to
be as well versed in this art as Miller.
arrival in Oakland on March 10, 1937 from Burbank, Earhart ran into
a week of bad weather, preventing her planned take-off on the 15th.1 Miller was coordinating the scheduling
of the USCG vessel Shoshone to leave Honolulu for Howland,
the USS Whippoorwill for the Howland/Honolulu half-way point,
and the USS Ontario to leave Pago Pago, American Samoa for
their respective stations. At the same time, reports from Howland
Island were not terribly encouraging regarding the final preparation
of the runways, as the workmen needed tractor spares that the Shoshone
was to bring.
top of all this, a Bureau of Air Commerce official, Mr. Reining,
sent a telegram to Earhart, with a copy to Miller saying that she
should contact Mr. Marriott or Mr. Bedinger, the supervisory aeronautical
inspector, for nonscheduled instrument rating or flight check ability
to fly entirely by instruments, as her flight permits would not
be released – Earhart’s pilot’s license was about to expire, and
she needed to take her biennial flight review prior to take-off
from Oakland.2 The next day, Bedinger
gave Earhart the instrument flight check, but the written and radio
tests “...not given account her desire to expedite and save engines.”3 This
is most curious, as the engines were relatively new and would not
need servicing for quite some hours, and a simple one hour test to
verify her radio skills would not significantly contribute to engine
wear. Nor was Earhart in a big hurry, as there were still four more
days planned prior to take-off. The desire to avoid the radio test
was probably the first contributing factor to Earhart’s failure to
reach Howland in July. Regardless, the BAC in Washington DC put her
permit in an airmail package to Oakland.
On March 12,
Miller sent out telegrams to all the major parties announcing that
Earhart was scheduled to leave Oakland on the 15th, weather permitting,
and would have Fred Noonan, Capt. Manning, and Paul Mantz aboard
the plane. Mantz was scheduled to leave the plane in Honolulu; Noonan
at Howland Island, and Manning in Darwin, Australia.
March 13, due to the heavy rains, Earhart asked through the Bureau
of Air Commerce whether she could use the San Francisco airport
with its 3000 foot runway. The problem would be that the prevailing
wind direction would necessitate a take-off towards obstruction
– not normally hazardous, but it might be for Earhart’s overloaded
plane.4 The BAC responded the next day
that it was up to local authorities alone to make that decision.5 Apparently,
the weather was so bad on the 15th that the take-off was delayed
another day. Earhart requested that the Navy loan her team an octant
for the transpacific flight from San Diego and that it be air shipped
to Oakland; LCDR George Manning, USNR, would sign for the octant.6 Approval
was provided, and the octant shipped on the 16th, arriving approximately
2:50 PM.7 Her scheduled departure was
deferred until the 17th, due to the weather, which was improving
was common knowledge among the parties involved that Earhart had
6210, 3105, and 500 kHz aboard her plane. It wasn’t until March
3rd, however, that a request was made to determine whether the two
ships in the half-way points could use those frequencies for communication.8 The
USCG Shoshone, scheduled
to visit Baker, Jarvis, and Howland Island, departed that same day
from San Francisco to Honolulu, and the CG representatives there
knew what radio capabilities that ship had. The following day, notification
was provided that the USS Whippoorwill, scheduled to be half-way
between Honolulu and Howland, could not operate voice above 3000
kHz.9 However, the Fleet Air Base, Pearl
Harbor, stated that it could install equipment for the 3105 kHz
series using gas-powered generator.10
Later that day, information from American Samoa Naval Facility at
Tutuila stated that the Ontario could not operate voice above
1000 kHz.11 On March 8th, Miller sent
a telegram to Putnam stating that the Shoshone could operate
on all frequencies Earhart intended to operate, but that the two
Navy vessels could only receive on all frequencies.12 On
March 9th, the Hawaiian Sector of the CG asked the San Francisco
Division to ask Miller what frequencies the Shoshone
should transmit voice and if 3105 and 6210 kHz were still to be
used by the crew of the plane.13 (Note
that 500 kHz is not mentioned as a primary frequency at this time.)
March 10th, the Shoshone left Honolulu without information
regarding what radio frequencies to use with Earhart or what her
modus operandi would be, a situation eerily similar to the
June/July trip of the Itasca. The USS Ontario also
left Pago Pago for her station half-way between Howland and New
Guinea, and without specific radio instructions to communicate with
Earhart. The Ontario was scheduled to arrive on station on
March 18th. Finally, on March 11th, Richard Black aboard the Shoshone
asked the USCG representatives at San Francisco to clarify the radio
plans for the Pacific legs of the flight, including frequencies
covered by plane's direction finder, transmitting frequencies, type
of emission and whether Earhart could use Morse code.14
March 12th, the USS Quail was directed to take the place
of the Whippoorwill, for unknown reasons.15
Late that same day, Earhart requested through the USCG office in
San Francisco that the USCG vessel Taney be detailed to a
position 200 miles northeast of Honolulu and act as a radio beacon
for her flight to Honolulu,16 which
action was approved the next day.17
Further, Earhart wanted the Makapuu radio beacon to be on full time.
The Lighthouse superintendent stated that the beacon could be on
for one minute, then off for two minutes, but that full, continuous
broadcasting had to be approved by the Lighthouse Commissioner.18 Approval for operation in fog conditions
was provided on the 13th.19 On March
13th, definitive information regarding radio procedures was issued
by Earhart, and forwarded by the USCG, San Francisco Division, and
sent to the Shoshone and Hawaiian Sector of the USCG. This
radio message stated that
should call the plane from one to six minutes past the hour, and
31 to 36 minutes past the hour. The first two minutes use 3105 kHz;
the second two minutes 6210 kHz, the third two minutes use 500 kHz
until contact is made. If no contact after three hours, the Shoshone
should transmit long dashes on 375 kHz, followed by the its call
letters. The plane will attempt to take bearings. Keep this up every
ten minutes, starting on the even hour, lasting for four minutes.
The plane will contact you after your transmission, following the
same procedure of ship to plane. All times are to be GCT; plane
call sign is KHAQQ, show searchlight as plane approaches Howland
during darkness and make smoke during daylight hours.20
For the flight
from Oakland, USCG San Francisco advised that it would
monitor the whole flight, and that Earhart will attempt to communicate
at 31 to 36 minutes past the hour for the first seven hours: 2 minutes
at 3105 kHz, 2 minutes at 6210 kHz, and 2 minutes at 500 kHz. For
Honolulu stations, the same procedures will be followed, but at
41 to 46 minutes past the hour. Calls will be made when necessity
demands it, and all times are GMT. PAA will handle all traffic and
direction finder bearings, answering the plane on 2986 kHz using
is provided to major Navy assets stating that
Earhart call sign KHAQQ, will transmit on 500, 3105, and 6210 kHz
using CW telegraphy and voice. Plane has a direction finder covering
200 to 1430 kHz will all wave receiver for telegraphy. A suggestion
was made to have a direction finder set up on Howland if practicable.
No amateur contacts will be made, and all transmissions will be
on the frequencies stated.22
an aside, the Chief of Naval Operations, Office 20 (Director of Naval
Communications), asked that the US Navy track the plane by available
high frequency directional finders for comparative tests between Navy
and PAA equipment.23 After Earhart landed
on Honolulu on the 18th, Richard Black sent a radio message saying
that a portable radiophone is available on Howland on 2670 kHz, and
can answer any questions regarding the runways as she passes over.24
We are indeed
fortunate that the navigational charts used by Noonan and Manning
still exist and are available at the Purdue University Library.
The base charts were developed by Pan American Airlines, and are
so marked. Apparently, Fred Noonan still had access to PAA materials
at this time. TIGHAR researchers have examined these charts, and
have determined the meaning of all markings on them. By reconstructing
the flight, based upon these notes, together with the radio messages
transmitted in flight, some interesting clues come out regarding
how Earhart and Noonan operated together.
left Oakland on March 17, at 4:32PM PST (0032/18 GMT) into a 14
mph wind using 1897 feet of takeoff on a muddy field in 25 seconds.25 She
was already in trouble, however, with the government bureaucrats:
she left without mosquito inspection and disinfectant.26 The
following radio transmissions were received during her flight:
position intercepted at 0842 GMT 31°N, 139°49°W, All's well."
Reported by USCG Hawaii at 0850 GMT.27
0028, KHAQQ on phone, reports all's well, no position." Reported
by USCG Hawaii at 1105 GMT.28
position at 1100 GMT 29°15'N, 147°38'W." Reported by
USCG Hawaii at 1125 GMT.29
position at 1200 GMT: 27°42'N, 149°40'W". Reported by
USCG Hawaii at 1245 GMT.30
intercepted from plane: speed approximately 155 land mph, approximate
time of arrival 0800 PST". Reported by USCG Hawaii at 1305 GMT.31
position at 1410 GMT: 25°N, 143°W." Later corrected
to 153°W. Reported by USCG Hawaii at 1455 GMT.32
intercepted at 0515 quote Will arrive 1620 GMT". Reported by
USCG Hawaii at 1555 GMT.33
plane off Diamond Head at 0545 Honolulu time." Reported by USCG
Hawaii at 1617 GMT.34
plane arrive Honolulu at 0600". Reported by USCG Hawaii at 1632
Bill Miller was on the phone to officials at Wheeler Field, as he
immediately sent out telegrams that Earhart arrived at 1625 GMT.36
are descriptions of the various markings on the two charts for the
Oakland-Honolulu flight, in chronological order. All times on the
charts are noted in GMT time.
123°25'W. This is a point along the rhumb line connecting
San Francisco to Honolulu.
123°22'W. Unknown determination of how position obtained,
but obviously not a DR.
123°31'W. Probably a DR point.
0230, 0300 GMT
Projected points along a line extending from Pt. Montara Radio
Beacon, spaced 60 nm apart, suggesting a 20 knot headwind expected.
This procedure of marking future, expected positions along a
course line was typical of Noonan's charting.
radio bearing taken upon a station (unnamed) outside of SF harbor.
LOP taken against Venus
radio bearing taken against Radio Bonita, and a LOP taken against
Sirius. When combined with the Venus shot, a position fix of
35°5'N, 127°57'W for 0317 GMT.
0400, 0430 GMT
DR points along a corrected baseline, passing through the 0317 GMT
fix and 0128 GMT fix, based upon 155 knots true over the ground.
A LOP taken against Alphecca. This is the only error on the
chart, as Alphecca is well below the horizon at this time and
location, despite it being in the proper look angle.
LOP taken against Sirius.
LOP taken against Polaris. Combined with the Sirius 0442 GMT
LOP, a position fix at 33°20'N, 131°50'W results.
0530, 0600, 0630 GMT
new set of projected DR points, based upon 150 knots true over
Position of commercial vessel President Harrison, at
LOP taken against Denebola.
LOP taken against Spica.
LOP taken against Sirius, which, when combined with the 0734
GMT LOP, provides a position fix at 0738 GMT of 31°25'N,
new projected DR position. At this time, the charts were changed,
reflecting the need to use a more westerly chart that includes
the Hawaiian Islands.
DR positions, based upon plane course and 0738 GMT fix, assuming
124 knots true over the ground.
makes course correction to a more southerly direction to account
for the northerly wind set.
LOP taken against Capella.
projected DR positions, using new base course.
LOP taken against Polaris.
LOP taken against Capella, which, when combined with the 1003 GMT
LOP, provides a position fix of 30°4'N, 145°30'W. A
new set of projected DR positions are plotted with this fix
for 1000 and 1030 GMT.
A major course correction is made to a more southerly direction,
as the set due to winds is still northerly.
1130, 1200 GMT
new set of projected DR positions are plotted in advance.
radio bearing is taken or provided against the PAA Makapuu radio
radio bearing is denoted against Makapuu.
plane course correction, again to a more southerly direction.
LOP against Antares.
LOP against Vega.
radio bearing taken/provided from Makapuu.
LOP against Polaris. When combined with the 1337 radio bearing,
a fix of 25°54'N, 153°26'N results.
plane course correction to a more southerly direction.
radio bearing taken/provided from Makapuu.
LOP taken against Vega, which, when combined with the 1450 radio
bearing, provides a navigational fix of 22°40'N, 156°37'W.
radio bearing taken/provided from Makapuu. This is the last
mark on the chart.
summary, Noonan made use of seven radio bearings, 14 star/planet
LOPs (of which nine were used for navigational fixes), and the plane
made only four course corrections. Analysis of the flight path versus
weather maps produced after this date show major concurrence with
the winds aloft patterns.37 It is clear
that the navigator’s major responsibility was to monitor the progress
of the flight, and to suggest course corrections only when deviations
from desired flight path became too extreme. Use of projected, future
DR positions allowed Noonan to check his forecasts vs. later navigational
fixes to update his speed and direction over the ground, and to
offer approximate positions, when necessary.
between the radio broadcast positions and the actual navigational
fixes reveals some interesting clues. First, there is no information
from radio messages regarding the first half of the trip.
- At 0842 GMT, a position of 31°N, 139°49′W was provided. This position
corresponds to the 0800 GMT DR position, extrapolated from 0738 GMT fix,
and was actually 31°10′N, 139°49′W. Thus, this position is
42 minutes old when broadcast.
1058 GMT, Earhart broadcasts that all is well, but no position
is provided. Note that this is an unscheduled radio broadcast.
- At 1125 GMT, USCG Hawaii broadcasts: “Intercepted position at 1100
GMT 29°15′N, 147°38′W.” This can be interpreted
to mean that the interception occurred at 1100 GMT, but the possibility
is that the 1100 GMT position is provided, which, in fact, is the
case. This is the DR projected position, based upon the 10007 GMT
fix, and having the plane make a course correction at 1045 GMT. Since
Earhart’s radio schedule broadcast is set for 41 to 46 minutes after
the hour, but the actual transmission is probably 11 to 16 minutes
past the hour. Thus, this position for 1100 GMT is at least 11 minutes
- At 1245 GMT, USCG Hawaii broadcasts that it intercepted Earhart
stating that her 1200 GMT position is 27°42′N, 149°40′W.
This is indeed the 1200 GMT DR projected position, with the last
fix at 1007 GMT and a course correction between the two times. Note
that this broadcast is consistent with Earhart’s original radio schedule.
This position is well over 41 minutes old.
- At 1455 GMT, USCG Hawaii broadcasts that they intercepted a position
at 1410 GMT of 25°N, 153°W. The map indicates that at 1410 GMT,
a course correction was made and that the DR position at that time
was approximately 25°N, 154°30′W. This is the radio message
that was corrected, and the radio operator listening apparently misconstrued
the longitude information. The previous navigational fix prior to
this DR was at 1339 GMT. If Earhart stayed on her radio broadcast,
she was providing a position well over 30 minutes old at 1441 GMT.
In all cases,
Earhart provided dead reckoning positions. Of the four documented
positions, three were provided with times, but the wording provided
by the USCG Hawaiian Sector leads to some ambiguity as to when Earhart
stated these positions. Interestingly, all four messages indicate
that the positions provided were well prior to the actual broadcast
times: 42, 11, 41, and 30 minutes. Based upon this analysis, one
can easily speculate that Noonan's method was to project future
positions via dead reckoning, and provide that information to the
pilot sometime prior to the radio broadcasts. In no instance does
Earhart provide timely information, nor does she provide an actual
navigational/celestial fix and time of the fix to help constrain
exactly where the plane was.
Earhart reasonably stayed on radio schedule, but also chose to use
the half-hour schedule when broadcasting during the second half
of her flight. This procedure was not expected, according to the
radio schedule promulgated by the USCG San Francisco Division described