Steve McLeod, who traveled to Alaska with his wife after the plane carrying a pilot and three Park Service employees disappeared in Southwest Alaska, said the reward stands at $15,000.
"They're out there somewhere," McLeod said in a telephone interview from King Salmon.
Mason McLeod, 26, Neal Spradlin, 28, and Seth Spradlin, 20, were aboard the de Havilland Beaver when it vanished. The plane was piloted by 47-year-old Marco Alleto.
Searchers have been looking for the plane since it disappeared but have found no sign of it. The plane was on a short flight over rugged terrain between Swikshak Lagoon and King Salmon.
Steve McLeod said he was hopeful somebody might spot something with increased flights in the area over the holiday weekend. "We need them found," he said.
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