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Overview - Flight Paths A, B and C

Assessment of three re-calculated flight paths

Research for this report includes assessment of three principal re-calculated paths, Path A, B, and C as defined below.

While each Flight Path will be examined in detail, in general, Flight Path A arrives almost everywhere, too early, and at 1912 GMT has actually over-flown Howland Island by enough to possibly preclude visual acquisition of the island, or the Itasca.

Flight Path B passes through the incorrectly reported 0519 GMT longitude position at 2 hours 18 minutes, and is then early at the 0718 GMT position report. AT 1912 GMT, this Path B arrives at the 1937 position coordinates for Howland Island.

Path B is also misaligned with navigation reporting position and time, and despite arriving at Howland Island, no person saw or heard the Electra. Path B may have passed through the 0519 GMT reported position, at an actual time of 0218 GMT, with these times misreported by Chater10 or Collopy11.

Reduced mission headwinds during the last 8 hours of the Lae to Howland segment, could result in Path B beyond Howland Island. A 5-10nm lateral error could result in nobody hearing or seeing the Electra, and the aircraft at a wind-adjusted Path B End-of-Navigation point, 20nm northeast-to-southeast of Howland Island.

The evidence suggests that the 0519 GMT reported longitude may be incorrect.

Correcting the 0519 GMT position report in longitude, with the actual position along the E 157.0 longitude, vice the E 150.7 longitude reported by Chater12, creates Path C. This path is reasonably aligned with all navigation reporting positions and times within 5% of the time the aircraft was at that point. Key factors such as entering the visual horizon to Nauru Island, where AE reported seeing lights on the island, are aligned in time and position. AE arrives slightly short of Howland Island due to what is possibly a navigational error, or miscalculation between 200nm and 100nm west of Howland Island, between 1745 GMT and 1815 GMT. One possible error is a sunrise celestial calculation of refraction, or dip angle computational error, of 31-70 nm depending on altitude at the time the fix was taken, such that “If the correction was not made, Noonan would have calculated that the Electra was nearer Howland Island than was the case.”13

Other errors are possible, including that FN made no errors and AE decided to descend slightly early, perhaps to keep Howland ahead of them to facilitate visual acquisition. This behavior would not be atypical for AE, as demonstrated on the Natal-Dakar segment when she turned opposite to FN’s suggested direction.

At the 1,000 feet altitude reported by AE approaching Howland Island, AE is at the edge of a visual acquisition range to the island and Itasca. Due to the rising sun directly ahead, visual acquisition would require being much closer to the Island.

Lateral track errors are possible, but there is no factual data upon which to make assessments of lateral navigation deviations from the planned course, and no evidence of lateral track error. On the contrary, the available data indicates AE adhered well to the track from Lae to Howland Island.

While all three paths are possible, Path A may be unlikely. Path B is possible, in that it deviates south of track for weather avoidance, and passes through the point chronicled at 0519 GMT, at an actual time of 0218 GMT. The numerals “5″ and “2″ could have been confused. Path C is likely.

The evidence for en route aircraft performance, mission times, position reporting, and key milestones, are all well aligned with navigation Path C. Even with reduced second-half mission winds, Path C concludes short of Howland Island, in the designed Primary Search Grid.

A final AE radio report at 2013 GMT with no further communication from AE, indicates a possible scenario in which the Electra contacted the water during terminal area maneuvering, perhaps due to pilot fatigue, loss of situational awareness, or due to fuel exhaustion, after 2013 GMT. A fuel consumption analysis (updated from Appendix 1) creates an endurance window until 2100 GMT. Fuel exhaustion between 2013 GMT and 2100 GMT is likely.

Evidence from Itasca weather reports for the morning of July 2, 1937 indicates light winds and a calm surface. Calm seas are difficult to fly over at lower altitudes because the pilot can lose awareness of altitude. At sea, the horizon and sea surface can blend into an uncertain mirage without sufficient detail to visually maintain desired altitude above the smooth water surface. Unintentional contact with the sea is a constant hazard during low altitude maneuvers over calm sea surfaces.