HONOLULU -- The U.S. Coast Guard suspended its search for a missing Big Island tour plane Thursday evening at sunset.

After a third day of searching, there was still no sign of the aircraft that disappeared on Tuesday, officials said.

The Hawaii County Fire Department is scheduled to have a helicopter continue the search Friday morning.

Sources confirmed the pilot on board the missing plane is Katsuhiro Takahashi, the chief flight instructor for Hawaii Flight Academy. The Japanese Consulate identified the missing passengers as Nobuhiro Suzuki, 53, and his wife Masako, 56. They are visiting from Chiba Prefecture, east of Tokyo.

The single-engine Cessna 172 with the tail number N 13713, was last seen at 12:45 p.m. above Volcanoes National Park. Authorities said the plane was scheduled to return to Kona 45 minutes later.

Clearer weather conditions made it easier to search for the missing plane and its three occupants on Thursday. The Coast Guard said its four aircraft have made more than 30 flights alone, covering 10,000-square miles. About 10 other aircraft also helped in the search.

"Unfortunately, we haven't found debris. There're no signals reported. It's really hard for us, being search-and-rescue professionals, and not to find anything so far. It's kind of discouraging, but like I said, we're just gonna keep continue searching," Petty Officer Luke Clayton said.

The Island Hoppers' pilot has plenty of experience flying on the Big Island, sources told KITV. Sources in the aviation industry said he has been flying there for three years, with several thousand hours of experience flying the same route on the island of Hawaii.

Island Hoppers canceled its other flights from its Kona operation to concentrate on finding its missing plane and passengers.

Pilots from other aviation schools and air tour operations on the Big Island have volunteered over the last three days to fly search missions.

Hart said Island Hoppers is extremely appreciative "of the tremendous support that has been shown by many other commercial aviation operators as well as private pilots on the island."