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Detailed Flight Analysis

Reviews previous documented flight characteristics to apply them to the final flight

Validated Statistical Data
Direct evidence includes AE’s flight performance on earlier World Flight segments, in which weather, winds and navigation challenges were similar to the final flight segment. Terrain was a factor in some mission segments, however, on the final flight segment, only Bougainville Island presented a terrain consideration with mountains reaching approximately 8,000 feet.

Wherever first-hand factual evidence was available from AE’s flight logs and accounts, that data was used to establish AE’s historical flight patterns. Analysis of an audit of World Flight mission segments provides important understanding for mission performance.

This data is also important when considering alternative flight profiles and mission outcomes, offered by various authors. When alleged mission flight parameters fall outside an established pattern of historical performance, the associated theory and conclusions demand careful scrutiny. The business analogy is that if a performance factor were well outside statistical Quality Assurance ranges, such as Six-Sigma, or Control Chart limits, it would exist as an abnormal data point, one requiring additional validation.

Some alternative theories about the World Flight, for example, require aircraft and mission performance that exceeds capabilities or that falls well outside historical patterns.

Winds
There are 7 weather reports relevant to this mission segment.

Reported wind speeds from weather observations are in mph. Only AE’s position report of wind speed was in knots at 0718 GMT.

Two reports are from Hawaii Headquarters, one issued 1 July and handed to AE, and one issued 2 July and broadcast from Lae to AE.31

Both ship-based and shore-based weather reports of upper winds are not extremely accurate in 1937. A meteorograph instrument was sent aloft under a tethered balloon or kite, where it recorded a few parameters for examination following retrieval. Upper winds may also have been established from an observation made by a qualified weather person.

Two reports are from Itasca, both at noon local time. One, on June 30, 1937 reported winds at 5000 feet from the east (090 deg) at 22 mph. The other, on July 1, 1937 reported winds at 7000 feet ENE (060 deg) at 30 mph and at 9000 feet ENE (060 deg) at 31 mph.32

One report is from AE at 0718 GMT (1718 local time) on July 2, 1937, as an in-flight position report, in which a reference to “winds 23 knots” is made. No direction was specified.33

One report is from the USS Ontario, July 2, 1937 bridge logs, that reported surface wind ENE (060 degrees) at force 3-4 (up to 16 knots) but it is only a surface report of sea state and winds.34

One report is from Nauru Island, on July 2, 1937 at 0800 local time GMT, approximately 3 hours prior to AE’s departure from Lae, and nearly 10-12 hours prior to AE’s arrival in the vicinity of Nauru Island, en route to Howland. In this report, upper wind values were reported at 4000 feet from 090 deg at 12 mph and at 7500 feet from 090 deg at 24 mph.35

This is evidence that at the mid-point of the Lae to Howland Island segment, upper winds were very close to those used by Long (26.5 mph) and our own baseline analysis.

Long36 assumed a constant headwind of 26.5 mph (23 knots) throughout his analysis. In arriving at this value, Long likely considered the AE in-flight position report at 0718 GMT reported wind value, and a single Nauru Island weather observation with wind direction and values linearly extrapolated to assess winds at AE mission altitudes of 8,000 and 10,000 feet.

While wind profiles are often not linear, over small altitude differences, a linear interpolation is sufficiently accurate for this analysis. Evidence exists that wind velocity was reduced, and direction shifted slightly, in the second-half of the mission.

For this research, the authors used upper winds from 070 deg magnetic at 23 knots, or 26.5 mph. On course to Howland Island, this was a headwind component of 23 knots, or 26.5 mph. Sensitivity analyses for second-half wind changes were completed, with resulting aircraft positions contained in the search grid.

Speeds - Aircraft and AE Performance
There are seven principal sources of historical and statistical in-flight performance data. These include L487; Kelly Johnson Telegrams; Electra capabilities in terms of power, speed, and fuel consumption, from operating manuals and Pratt-Whitney engine data; AE’s first-hand reports during her World Flight performance37; research by Long; and research by Swenson and Culick38 with aerodynamic and engine performance research.

Definition of speed is important in understanding a Lae-Howland specific segment analysis.

Below is a table compiled from two reference sources, Long39 and Finch.40 The data was crosschecked with notes reported by AE41, providing a single source for historic mission segment examination.
The data show that in 30 World Flight legs, excluding 3 test flights of short duration (less than 2.5 hours) the average ground speed is 142.1 mph.

This is useful in assessing various AE reported speeds, that often omitted units (statute or nautical miles per hour), or what type of speed was being used (indicated, true or ground speed). AE frequently omitted other details, such as altitude, outside air temperature, and winds, from her in-flight reports.

Statistical data combined with report times and positions, helps to assess the reasonableness of aircraft performance and to corroborate other data.

A report of speed in knots likely resulted from FN calculations, handed to AE for reporting, since FN likely worked in nautical miles from navigation charts, and AE’s airspeed indicator was calibrated in statute miles per hour. AE, simply due to the state of aviation in 1937, most likely did not possess the tools to convert statute miles per hour to knots, or to work between indicated, true, and ground speed, from the cockpit and without reference to published tables or graphs.

AE’s Lae to Howland performance is defined from corroborating power settings, Brake Horsepower, Cambridge Fuel Analyzer indications, L487 and Kelly Johnson recommendations, and statistically validated to calculated and historical values. These values can be used to determine flight path data, with reasonable assurance that a re-calculated flight path represents an accurate calculation.

Table 1 - Segment Speed Performance

FROM TO

DATE

TIME

DIST NM

FLIGHT TIME

AVG GS KTS

AVG GS MPH

OAKLAND BURBANK

20-May-37

1550

283

2.25

125.78

144.75

BURBANK TUCSAN

21-May-37

1425

393

3.33

118.02

135.82

TUCSON NEW ORLEANS

22-May-37

730

1070

8.67

123.41

142.02

NEW ORLEANS MIAMI

23-May-37

910

586

5

117.20

134.87

MIAMI SAN JUAN

1-Jun-37

556

908

7.56

120.11

138.22

SAN JUAN CARIPITO

2-Jun-37

650

492

4.53

108.61

124.99

CARIPITO PARAMARIBO

3-Jun-37

848

610

4.83

126.29

145.34

PARAMARIBO FORTALEZA

4-Jun-37

710

1142

9.33

122.40

140.86

FORTALEZA NATAL

6-Jun-37

650

235

2.08

112.98

130.02

NATAL SAINT-LOUIS

7-Jun-37

313

1727

13.37

129.17

148.65

SAINT-LOUIS DAKAR

8-Jun-37

905

100

0.87

114.94

132.28

DAKAR GAO

10-Jun-37

651

1016

7.92

128.28

147.63

GAO FORT LAMY

11-Jun-37

610

910

6.63

137.25

157.95

FORT LAMY EL FASHER

12-Jun-37

1224

610

4.1

148.78

171.22

EL FASHER KHARTOUM

13-Jun-27

610

437

3.25

134.46

154.74

KHARTOUM MASSAWA

13-Jun-27

1050

400

2.83

141.34

162.66

MASSAWA ASSAB

14-Jun-37

730

241

2.43

99.18

114.13

ASSAB KARACHI

15-Jun-37

313

1627

13.37

121.69

140.04

KARACHI CALCUTTA

17-Jun-37

725

1178

8.33

141.42

162.74

CALCUTTA AKYAB

18-Jun-37

705

291

2.45

118.78

136.69

AKYAB RANGOON

19-Jun-37

842

268

2.5

107.20

123.37

RANGOON BANGKOK

20-Jun-37

630

315

2.72

115.81

133.27

BANGKOK SINGAPORE

20-Jun-37

1027

780

6.47

120.56

138.74

SINGAPORE BANDOENG

21-Jun-37

617

541

4.33

124.94

143.78

BANDOENG SURABYA

24-Jun-37

1400

310

2.58

120.16

138.27

SURABAYA BANDOENG

25-Jun-37

600

310

2.5

124.00

142.70

BANDOENG SURABAYA

26-Jun-37

1154

310

2.6

119.23

137.21

SURABAYA KOEPANG

27-Jun-37

630

668

5.5

121.45

139.77

KOEPANG DARWIN

28-Jun-37

630

445

3.43

129.74

149.30

DARWIN LAE

29-Jun-37

649

1012

7.72

131.09

150.86

AVG

119.49

142.10

SDEV

12.14

This graph below of average speeds flown on each World Flight mission segment, illustrates two important conclusions.

AE typically operated at parameters specified by experts, especially for longer duration flights.

AE’s performance consistently adheres to a reasonably small range of speeds.

The data shows a larger variance in speed for shorter segment lengths. As the segment length increases, the speed variance decreases, approaching speeds recommended by the L487 Report42 and Kelly Johnson.43

This process increases confidence in the preflight planning, flight parameter specifications, and, for the few longer segments flown by AE, a sense that these values were typical.

The final mission segment is not included in this data, since a definite completion time was not established.

Figure 5.jpg

Figure 5 - Average World Flight Ground Speed

This graph below depicts flight segment times, providing an interesting perspective of some of the human factors involved in this flight.
The 30 World Flight times in the graph average 5.1 hours per flight segment. For comparison, the Lae to Howland segment was planned for approximately 18 hours, and lasted in excess of 20 hours.

The maximum flight time prior to Lae, was 13.37 hours, recorded for two mission segments.

No other mission segment was more than 10 hours.

AE had completed flights of durations approaching the length of the Lae-Howland segment.

On May 20-21, 1932, AE completed a solo transatlantic crossing in 14 hours 56 minutes.

On August 24-25, 1932 AE completed a solo non-stop transcontinental crossing in 19 hours 5 minutes.

On July 7-8, 1933, AE completed a transcontinental crossing in 17 hours 7 min.

On January 11, 1935 AE completed a solo flight from Honolulu to Oakland in 18 hours.

On May 8, 1935, AE completed a Mexico City to Newark flight in 14 hours 19 minutes.

AE was no stranger to long flights, yet all were completed 2-5 years earlier, none were to islands, and none required a need for maximum range performance and fuel management to the level required from Lae to Howland Island.

This data provides insight into not only the challenge undertaken by AE and FN, but the complexity of this operation relative to their previous experience.

Figure 6.jpg

Figure 6 - Average Segment Length

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