Ken Fitzpatrick got an unexpected call from his brother, Bill, one afternoon two summers ago.

Bill, 59, a retired National Parks Service pilot, had just flown cross-country from Northern California to Danbury Municipal Airport and wanted to grab lunch.

"I said, `I had no idea you were in town," Ken Fitzpatrick said. "He just said, `Meet me at the airport.'"

Ken Fitzpatrick drove from his Ridgefield home to the airport, where he found his brother waiting at the hangar. But something was off.

"I said, `Where's the plane?'" Fitzpatrick recalled. "He pointed at this little thing that could fit in the back seat of an SUV and said, `There it is.'"

Bill was transporting the two-seat plane to its new owner, who lived on Nantucket. Along the way, he made fuel stops at other airports using corkscrew landings, a tricky maneuver for the most experienced of fliers.

"He's an airplane cowboy that really knows how to fly," Fitzpatrick said. "A pilot's pilot is what I would call him."

Fitzpatrick said that's why he is puzzled as to how his brother, who had been flying since the age of 17, disappeared June 22 while flying from Senegal to the Republic of Congo.

Bill Fitzpatrick, a pilot for the nonprofit African Parks, which owns seven state parks on the continent, was transporting one of the company's recently acquired Cessna 172s to his base in the Odzala-Kokoua National Park. He was scheduled to make a fuel stopover in the Cameroonian city of Douala, but African Parks was notified June 23 that he never arrived.

The last radio contact from the plane occurred at 10 p.m. local time just as Fitzpatrick entered Cameroon from Nigeria, as the plane was being handed off to Cameroonian air traffic control. The area is known to harbor members of the Islamic terrorist group Boko-Haram, the group responsible for the kidnapping more than 200 girls from a Nigerian school in April.

Ken Fitzpatrick said he has narrowed down his brother's fate to three possibilities: The plane crashed and the wreckage hasn't been found; that Bill turned the plane around in an emergency and landed in a remote, possibly unstable region of Nigeria; or that someone with ulterior motives was on board with him.

"We know one of those happened, but we don't know which one," Fitzpatrick said. "We feel helpless that we can't do anything to help."

The U.S. State Department has been assisting in the search and Fitzpatrick said African Parks has been "fabulous" in coordinating it. The company offered a $1,000 reward for information about the whereabouts of the plane, but villagers have not been forthcoming and remain reluctant to speak with outsiders.

Fitzpatrick said he and Bill's wife, Paula, are doing everything they can to publicize the disappearance and reach people on the ground in Nigeria and Cameroon. He said he hopes word will eventually reach a missionary group in Africa that residents would be willing to speak with.

"We agreed that we needed to ratchet this up and get people involved," Fitzpatrick said. "Perhaps we won't get any results, but let's at least get the word out."

He said Bill is a survival expert who teaches law-enforcement officers how to survive in remote areas of the planet. That's why Ken remains hopeful, though his concern grows as time passes with no word.

"My brother, he's a survivor," Fitzpatrick said. "But as each day and each week go by, things start to go through your head."