Operations Specialist Lindsey Kirby said the Coast Guard was notified after 7 a.m. Sunday.
Kirby said the aircraft contacted the Juneau tower about 6:43 a.m. about approaching for a landing.
KINY reported the plane was asked to contact the tower again at the four-mile mark, but it never did.
Authorities believe the plane is a Cessna 182 with one person on board.
The Coast Guard is searching around Stephens Passage and the east side of Mansfield Peninsula.
Kirby said searchers have picked up an emergency locator transmitter signal.
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