Did Amelia Earhart survive her plane crash? This is the most likely theory, with evidence emerging that she was making contact for days after her plane disappeared.
The International Group for Historic Aircraft Recovery (TIGHAR) believes Earhart safely landed her plane when it disappeared in 1937 and died as a castaway.
During a presentation in the US last month, TIGHAR's Ric Gillespie backed up all of the group's theories.
Earhart's plane was last seen on the radar on July 2, 1937.
After becoming the first woman pilot to fly solo across the Atlantic Ocean, she embarked on a mission to fly 47,000km around the world.
But on July 2 1937, four months after beginning her trip, she found herself in trouble.
She was flying at 375m looking for Howland Island, southwest of Honolulu, but was low on fuel.
It is believed she was not as close to the island as expected so she safety landed on another island, believed to be Nikumaroro, also known as Gardner Island, which is surrounded by a reef and about 640km southeast of Howland Island.
Mr Gillespie said from the time the plane vanished off the radar on July 2 to July 6, there were more than 100 radio transmissions from Earhart calling for help.
A woman in Melbourne even picked up her frequency.
"People started hearing radio distress calls from the aeroplane and they were verified," Mr Gillespie said.
About six hours after she went missing, a very weak and unreadable voice was picked up by credible radio operators. They recognised her voice.
A housewife in Texas listening on a short-wave radio a short time later also heard Earhart's pleas. She heard the plane had landed part in water and part on land.
Mr Gillespie said Earhart told radio operators she was injured, but not as badly as her navigator Fred Noonan.
"She's out there calling for help," Mr Gillespie said.
He believed that Earhart landed safely with some petrol left in the tank, because she wouldn't have been able to work the radio without the engine running.
Her local transmitter also would not have worked if she landed in water.
What's fascinating about Mr Gillespie's theory, is a girl from St Petersburg in Florida who was 16 when Earhart went missing.
According to Mr Gillespie, she was at home listening to her radio when Earhart interrupted the frequency.
The girl grabbed a notebook next to her radio and began to transcribe Earhart's call for help.
Mr Gillespie now has the notebook and he said the whole thing read like a modern 911 call.
"It's very confusing, some things don't seem to make sense," he said.
"In several places in the notebook she wrote 'New York, New York'.
"That's how she wrote New York City or something that sounded like New York City."
Mr Gillespie said there is a shipwreck at the location where they believe Earhart landed, a ship that was called SS Norwich City, which was abandoned at the island in 1929.
So with all this seeming to add up, why hasn't anybody found it yet?
Mr Gillespie said TIGHAR had taken a number of trips to the destination but haven't had the right equipment to find debris from Earhart's plane.
It is believed the tide washed it out to sea.
Next July will mark the 80th anniversary since Earhart went missing, and TIGHAR plans to go on another expedition to Gardner Island, but this time, use submarines.
Mr Gillespie said it would be the best tool to find any debris underwater.