Amelia Earhart by W. C. Jameson Page A

these early days of navigation, it was common for a navigator to plot a sun line—a single line of position from the sun plotted on a chart at right angles to it. The sun line would, with a fair degree of accuracy, update their position along an east-west course, but it was not particularly helpful relative to providing information pertinent to their maintaining the intended course directly to the island or veering off to the north or south. Because Howland Island was so small, any slight deviation from the intended course could cause the Electra to fly past it without Earhart or Noonan seeing it.
    The way to compensate for a problem such as this was for the navigator to make a decision about the maximum distance it was reasonable for the plane to be accidentally off course to the north or south. The navigational term for this is the “area of uncertainty.” The navigator would make a choice to veer either north or south from the presumed direct course. When the sun line of position indicated that they had progressed eastward as far as Howland Island, the pilot would then turn in the appropriate direction (north or south, depending on which direction the navigator chose to veer from the main course), and then, theoretically, fly directly to the intended destination, in this case, Howland Island. Flying the extra off-course for miles would delay their arrival time to around 1912 GCT.
    By 1715 GCT, the Electra was running on the last of the fuel supply—a wing tank that carried ninety-seven gallons. Both engines could run off of this tank. With a fuel consumption rate of twenty gallons per hour, they would be able to remain airborne for another two- to two-and-a-half hours.
    At 1744 GCT, Earhart transmitted, “Want bearing on 3,105 kilocycles on hour. Will whistle in mic.” After pausing a moment, she continued, “About two hundred miles out, approximately.” A few seconds of whistling followed, and she closed with the single word, “Northwest.” The sun was now coming up.
    At 1815 GCT, Earhart broadcast, “Please take bearing on us and report in half-hour. I will make noise in microphone. About one hundred miles out.” Noonan plotted the sun line that ran 157–337 degrees across their course. At approximately 1833 GCT, the Electra was around sixty-five miles from its destination. Earhart began her descent, for it was imperative they get below the cloud line in order to be able to spot the island. At around one thousand feet, they were below the cloud base.
    Presuming they were following Noonan’s plan, Earhart would have turned north or south toward Howland Island around 1902 GCT, following the 157–337 sun line. The island should only be about fifteen to twenty miles away. It can also be presumed that because of the low angle of the sun, the pilot and navigator had to deal with a significant amount of glare coming off the ocean surface.
    At 1912, Earhart sent her scheduled transmission on 3,105 kilocycles: “KHAQQ calling Itasca . We must be on you but cannot see you. But gas running low. Been unable to reach you by radio. We are flying at altitude of one thousand feet.” By prearrangement, when the Electra got close to the island, the Itasca would release an abundant column of smoke. Since they were positioned just off Howland, the island would therefore be easier to spot. It has been estimated that such smoke could be seen from forty miles away and more.
    The truth is, Earhart was nowhere near the Itasca . Based on an analysis of the radio logs by Paul Rafford as well as a study of the radio transmitting characteristics of Earhart’s Electra, it was determined that she was 150 miles north-northwest of Howland Island when she made the above transmission.
    By 1928 GCT, the Electra would have been flying along the 157–337 sun line for about forty miles. Earhart and Noonan could see neither the island nor the smoke from the Itasca . By this time,