"It is truly an anomaly, and when you're looking for man-made objects against a natural background, anomalies are good," he added.
A number of artifacts recovered by TIGHAR during 10 expeditions have suggested that Earhart and her navigator, Fred Noonan, made a forced landing on the island's smooth, flat coral reef. Gillespie and his team believe the two became castaways and eventually died there.
In July 2012, Gillespie and his crew returned to Nikumaroro to carry out an underwater search for the plane with a torpedo-shaped Autonomous Underwater Vehicle (AUV) and a Remote Operated Vehicle (ROV).
Multi-beam sonar mounted on the ship mapped the underwater terrain and the AUV collected a volume of side-scan data along roughly 1.3 nautical miles of shoreline off the west end of Nikumaroro, while the ROV, capable of reaching depths of 3,000 feet, produced hours upon hours of high-definition video.
Plagued by a number of technical issues and a difficult environment, the hunt did not result in the immediate identification of pieces from Earhart's Lockheed Electra aircraft.