She may not have been familiar with the then-new model of the plane, which had a fuel tank just behind the cockpit. When full, it could have shifted the plane's center of gravity, sending it into a low-altitude stall from which it could not have recovered, Macha theorized. Or Silver could have been momentarily blinded by the lowering sun as she broke through the cloud cover and then lost her orientation.
Macha hopes to find the plane with volunteer divers and the help of fishing boat captains or others whose sonar may already have picked up evidence of the wreck.
"It seems doable," Macha said of prospects of finding the plane after all these years. "It's probably in water that is only about 50 or 60 feet deep, maybe less."
Although the plane is probably corroded and covered with algae, it would still register on sonar. And although the letters painted on the fuselage would have long since disappeared, the identifying number plates embedded in several parts of the plane would still be legible.
Sacramento attorney Ken Whittall-Scherfee, whose wife, Laura, is the granddaughter of Silver's surviving sister, said he recently wrote to Air Force officials in the hope that they can help with documents that could verify what happened to Silver.
"This has been a fascinating family story," said Whittall-Scherfee, who became interested in aviation history even before he met his wife and heard about her lost great-aunt.
"It would mean a lot to my wife's grandmother to finally be able to know what happened, to get some resolution of the mystery."
Elizabeth Whittall, 88, remembers her sister as a courageous woman who loved to fly and was proud to be so important a part of the war effort. Born in New Jersey to a prosperous chemist and a homemaker active in pioneering family planning movements, Gertrude Tompkins, the youngest of three girls, had a hard time as a child.
"She stuttered, and she had to work very hard" to overcome it, Whittall said in an interview from her home in Vero Beach, Fla. Gertrude attended a college in Pennsylvania where she studied horticulture, her life's passion--until she discovered flying.
"She loved to fly, and when she became a WASP, you could see her just glowing. She had finally found what she wanted to do," Whittall said.
Tompkins married Silver, a New York businessman who was also in the military, and the two planned to make a home after the war and adopt the orphaned daughter of one of his relatives.
Whittall said she is certain that her sister would have found a way to keep flying after the war. And she took some comfort from the fact that her sister died doing something she loved for a cause she deeply believed in.
Although Whittall firmly asserts her belief that the military did all it reasonably could at the time to find her sister, she is nonetheless grateful for Macha's efforts now.
"We were very close when we were growing up. And she's the only one [of the WASPs] who hasn't been found," Whittall said, adding that Macha's success "would close a chapter."