A friend of the owner of a plane that vanished on its way to Victoria, B.C., on Tuesday is now offering a $10,000 reward for the recovery of the aircraft.

Greg Fedune hopes the money will entice back country enthusiasts, ATV riders and dirt bikers to aid the ground search.

Two Canadian Forces aircraft and seven civilian planes were in the air flying over southern B.C. Thursday looking for the plane that disappeared earlier this week with its pilot and three passengers shortly after taking off at the Penticton Airport.

The Piper PA24 hasn't been heard from since leaving on a two-and-a-half hour flight to Victoria. The craft was reported missing four hours after it left the airport.

Searchers are focusing their efforts on the mountainous region between Penticton and Chilliwack because the private airplane never appeared on Metro Vancouver radar.

Maj. James Pierotti of the Joint Rescue Coordination Centre said that if the aircraft had gotten into trouble at some point west of Chilliwack, it would have been able to talk to an air traffic controller.

"That is why we're not focused on the Lower Mainland; we are focused more on the mountainous region."

CTV British Columbia's Kent Molgat reported that it is customary for pilots to call in to the airport after taking off.

Because the airport did not receive such a call from the missing aircraft, there has been some speculation that the plane ran into problems soon after takeoff.

The plane did have an emergency locator transmitter, but crews have not picked up any transmission so far.

"We have heard nothing so far," Pierotti said.

The Piper is owned by Rama Tello, who, along with his brother and two friends, were confirmed to be on the missing plane. All are under the age of 40.

With files from The Canadian Press and a report from CTV British Columbia's Kent Molgat