A search resumed Monday for two Arizona men whose single-engine plane has been missing nearly a week.

A pair of aircraft were searching Monday near the Grand Canyon in Arizona and one each on both sides of the mountains near Cove Fort, about 150 miles southwest of Salt Lake City.Mission coordinator Ron Lillie said the search may be suspended after Tuesday, then continue again over the weekend.

More than 100 searchers in the air and on foot looked Sunday.

Sherman Flake, 52, and his 19-year-old son Scott were last seen refueling their Piper Tri-pacer Wednesday morning at a convenience store near Fillmore. The plane then taxied off a road and headed for Chandler, Ariz., said Al Laney, a Civilian Air Patrol spokesman in Utah.

"The family wasn't expecting him until yesterday, but he filed a flight plan so the FAA (Federal Aviataion Authority) says we got a lost pilot," Laney said Sunday, the fifth day of the search.

"The status is we felt like we had a good search today," said Laney. "We're checking on two leads today, but we don't feel good about them."

Civilian and private planes were checking out every lead, including scoping out wildfire scenes that may have been started by a plane crash, Laney said.

"We do have a ground crew going in near Kanab about a sighting," he said. But Boy Scouts learning communicating techniques with mirrors may skew some possible sighting reports.

Searchers flew 42 missions, or departed airfields 42 times, Sunday in the search that has covered an area from Fillmore south to Arizona, said Laney.

"We get the planes low and slow, 800 to 1,000 feet from the ground" to peer for the missing father and son, he said. "Right now, we're just waiting for the aircraft to return. Then we'll decide" whether to continue searching.

The Flakes left Burley, Idaho, last Wednesday en route to Chandler, with a stopover in Fillmore. When the pair failed to arrive in Arizona as expected, the search began.

The 117 searchers Sunday scanned from Fillmore to Hurricane, Laney said, with a ground crew prowling the Kanab area to check up on the possible plane sighting.