Amelia Earhart's missing plane could be visible in sonar image captured off remote Pacific island Sonar images taken at an uninhabited Pacific island may solve the mystery of missing aviator Amelia Earhart. THE mystery behind the disappearance of pioneer aviator Amelia Earhart may be a step closer to being solved after researchers discovered what they think is a piece of wreckage from her plane. The International Group for Historic Aircraft Recovery (TIGHAR) says a grainy sonar image of the edge of an uninhabited Pacific island could show a piece of Earhart's plane. TIGHAR says the sonar image shows an anomaly at 600 feet in the waters off Nikumaroro Island in the Republic of Kiribati. The island is about 560km from Earhart's target destination, Howland Island. Earhart, 39, had been on a round-the-world flight following the path of the equator in her Lockheed Electra when she disappeared on July 2, 1937. TIGHAR executive director Ric Gillespie told Discovery News: "What initially got our attention is that there is no other sonar return like it in the entire body of data collected," Ric Gillespie, executive director of TIGHAR, told Discovery News. It is truly an anomaly, and when you're looking for man-made objects against a natural background, anomalies are good. TIGHAR researchers say the sonar image shows a "small debris field of objects in relatively shallow water - 61 metres" which forensic imaging specialist Jeff Glickman "feels 100 per cent certain ... are man-made." The image shows "a strong return from a narrow object roughly 22 feet (6.7m) long oriented southwest/northeast on the slope near the base of an underwater cliff," Discovery News reports. "It gives the impression of being an object that struck the slope at the base of the second cliff at a depth of 187 metres, then skidded in a southerly direction for about 40 metres before coming to rest," TIGHAR's research notes say. The sonar images were captured during a July 2012 expedition during which the crew used an Autonomous Underwater Vehicle (AUV) equipped with a multi-beam sonar to scan the area around the island. The purpose of the research trip was test the theory that Earhart landed her plane on the reef at Nikumaroro Island and that it was washed off the edge, broken up and then sank. The expedition was plagued by delays and technical issues and the anomaly in the sonar image was only spotted earlier this year. TIGHAR has been searching for the remains of Earhart's plane for years. The project is funded through public donations. Earhart at the controls of an aircraft in Essonne, France circa 1930. Earhart was the first female pilot to fly solo across the Atlantic, receiving the US Distinguished Flying Cross for setting the record. Several conspiracy theories surround her disappearance, including that she was captured by the Japanese and held as a spy, and that she completed her flight, changed her name and lived in New Jersey.