Amelia Earhart didn’t simply vanish July 2, 1937, as most have been led to believe. Actually, radio transmissions were received long after her last known voice transmission.

Hours after the last noted radio transmission, distress signals began coming through. It was these distress calls that gave the Navy and U.S. Coast Guard guidance.

Related: Amelia Earhart Plane Wreckage Found?

When the search did not turn up either the plane, Earhart or any wreckage, the signals were considered unreliable and ignored–until recently.

The International Group for Historic Aircraft Recovery (TIGHAR) researchers have taken another look at the 120 distress signals sent from July 2nd, when Earhart went silent, to July 18th, when the search for the aviator was called off.

Using radio wave analysis programs, antenna modeling software and digitized information management systems, TIGHAR researchers decided that at least 57 of the transmissions were credible. In fact, more than one receiving station heard at least four of the transmissions.

Credible signals ignored in Amelia Earhart case

Credible signals ignored in Amelia Earhart case