A poster of the missing Beechcraft Bonanza is tacked on the wall at Canadian search headquarters in Whitehorse. (CBC)More military and volunteer personnel joined the search in the Yukon Thursday for an American couple whose small plane went missing almost two weeks ago.

Eight aircraft in all are searching for the red and white Beechcraft Bonanza, with a 70-year-old pilot and his 68-year-old female passenger on board.

The aircraft departed June 20 from an airstrip at Wolf Lake, near Anchorage, Alaska. It never arrived in Whitehorse later that day. U.S. and Canadian rescue crews have been searching along the Alaska-Yukon border since then.

Capt. Craig Ellestad, who is leading Canadian search efforts for the federal Defence Department, told CBC News that two military aircraft came up to Whitehorse to help, including a Hercules from Winnipeg and a Buffalo from Comox, B.C.

The military searchers are joined by volunteers and six aircraft from the Civil Air Search and Rescue Association.

"The Hercules brought in about 10 more people, so that brings about a total of 90 people who are here helping out with this effort," Ellestad said Thursday.

Search master Capt. Craig Ellestad said good weather has helped crews scour three possible routes the plane might have taken on the Canadian side of the border. (CBC)He added that the Hercules "really is helpful along some of the higher terrain right along the Canadian border."

Search officials say the Iowa-based couple was embarking on a camping trip and have tents, stoves and other survival equipment aboard the aircraft.

The plane did have a standard emergency transmitter on board, but no signal has been detected from it.

Good weather over the past few days has helped searchers as they scour an area stretching over 21,000 square kilometres.

The crews are pursuing three possible routes the plane could have taken between Whitehorse and the Alaskan border, Ellestad said.

American crews are mirroring search efforts on their side of the border, he added.