AP file

This undated file photo shows Amelia Earhart. A new expedition is attempting to find the wreckage of the plane she flew in her attempt to circumnavigate the globe in 1937.

Seventy-five years after Amelia Earhart went missing over the Pacific Ocean while attempting to circumnavigate the globe, a new expedition will search the waters in hopes of resolving the longstanding mystery of what happened to the American aviation pioneer.

The Niku VII expedition will search the underwater reef slope off the west end of Nikumaroro, formerly Gardner Island, an uninhabited coral atoll in the Pacific, looking for signs of wreckage from Earhart’s Lockheed Electra.

The expedition is being led by Richard Gillespie, executive director of The International Group for Historic Aircraft Recovery, or TIGHAR (pronounced “tiger”),  a Wilmington, Del.-based nonprofit group that promotes aviation archaeology and historic preservation.

“The primary search area is based upon the hypothesis that the aircraft landed safely on the reef and remained there for several days before being washed over the reef edge by rising tides and surf,” TIGHAR says on its website in explaining the mission. “Aircraft debris reportedly found and used by island residents in later years, and aircraft parts found by TIGHAR in the abandoned village strongly suggest that the aircraft broke up in the relatively shallow surf zone.”

Earhart became the first woman to fly solo across the Atlantic Ocean in May 1932, when she took off from Harbour Grace, Newfoundland, and landed the next day in Londonderry, Northern Ireland.

In March 1937, she attempted to fly around the world in a twin-engine Lockheed Electra, but a tire blew out during takeoff from Hawaii and she crashed.

After her plane was repaired, Earhart, then 39, set out on a second attempt from Miami in June 1937 with navigator Fred Noonan. They were on the last leg of the flight when the plane went down on July 2, 1937, while approaching Howland Island, a remote coral island in the central Pacific Ocean about 1,700 nautical miles southwest of Honolulu.

U.S. Coast Guard and Navy ships searched the area but turned up no sign of the crew or the plane. Earhart’s disappearance remains a mystery to this day.

Many researchers believe Earhart’s plane ran out of fuel and the pair ditched at sea. But other theories abound, with some conspiracy theorists suggesting Earhart was caught and held by the Japanese as a spy.

The expedition led by TIGHAR assumes that the pair reached Gardner Island, then a British possession, and survived for an unknown period of time.

Crews using underwater robots will search the waters with high-frequency sonar and take black-and-white photos down to a depth of nearly 5,000 feet (1,500 meters), according to TIGHAR. The expedition will be able to examine sonar targets using high-definition video down to a depth of 3,300 feet (1,000 meters).

The object of the expedition is to locate, identify and photograph any wreckage found. There are no plans to recover any wreckage.

"What we're hoping for is to come back with good imagery, photographs, of wreckage that's conclusively, unquestionably pieces, at least, of Amelia Earhart's Lockheed Electra aircraft; that's the goal," Gillespie told the BBC.

A documentary on the expedition will be broadcast on the Discovery cable television channel.

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