It emerged that transmission of credible signals occurred in periods during which the water level on the reef was low enough to permit engine operation.
According to Gillespie, at least four radio signals are of particular interest, as they were simultaneously heard by more than one station.
The first signal, made when the pilot had been officially missing for just 5 hours, was received by the Itasca, and two other ships, the HMS Achilles, and the SS New Zealand Star.
The Itasca logged "We hear her on 3105 now - very weak and unreadable/ fone" and asked Earhart to send Morse code dashes.
The Achilles did not hear "very weak and unreadable" voice, but heard Itasca's request and heard dashes in response. The SS New Zealand only heard the response dashes.
In other cases, credible sources in widely separated locations in the U.S., Canada, and the central Pacific, reported hearing a woman requesting help. She spoke English, and in some cases said she was Amelia Earhart.
In one case, on July 5, the U.S. Navy Radio at Wailupe, Honolulu heard a garbled Moorse code: "281 north Howland - call KHAQQ - beyond north -- won't hold with us much longer -- above water -- shut off."