Searchers are unsure whether the single-engine plane that disappeared July 13 between Central Utah and Northern Arizona was equipped with an functional electronic locating transmitter.

Ron Lillie, Emergency Service Director of the Civil Air Patrol in Utah, said if a transmitter were running, a satellite would have picked it by now.Lillie said rescue efforts to find 52-year-old Sherman Flake and his 19-year-old son Scott will continue "full steam ahead until they find them or until someone with greater authority than his tells him to stop."

"There are a lot of people and a lot of planes out looking for them," Lillie said.

The Flakes left Burley, Idaho, where they were working a construction job, last Wednesday en route to their home in Chandler, Arizona. The pair stopped at a convenience store near Fillmore for gas. The plane, a Piper Tri-pacer, then taxied off a road and headed for Chandler.