On the afternoon of May 9, 1927, Anson Berry, fishing in his canoe on Round Lake in eastern Maine, heard what sounded like an engine overhead, approaching from the northeast. He could not see the airplane, if that was what it was, because of a heavy overcast.

The engine sounded erratic. Moments later it stopped, and Berry heard what he described years later as a faint, ripping crash. The afternoon was wearing on, and the always unsteady spring weather was worsening; already rain was beginning to fall. Perhaps because he did not trust the weather to hold, Berry did not investigate what he heard.

If he had, one of aviation’s most puzzling mysteries might have been solved. As it is, no one yet knows what happened to Captains Charles Nungesser and François Coli , who left Paris the morning of May 8, 1927, to attempt the first east-to-west transatlantic flight in history. Apparently they disappeared into the North Atlantic, forced down by the weight of ice on the wings of their biplane, named the White Bird.

But 16 persons in Newfoundland saw or heard an airplane pass overhead the morning of May 9. Given the times and locations of those sightings, quite possibly what Berry heard was the White Bird.

Public interest in transatlantic flight had been ignited on June 14, 1919, when Captain John Alcock and Lieutenant Arthur brown made the first nonstop crossing from St. John’s, Newfoundland, to Clifden, Ireland. Before Nungesser and Coli’s attempt, seven more west-to-east crossings had been made. But now the goal was to connect New York and Paris, a nonstop flight more than...