HONOLULU -- Aircraft experts are racing to get a specially-modified plane ready to help recover 12 people on one of the most remote islands in the Pacific Ocean.

Palmyra Island is about 1,000 miles southwest of Hawaii. The Nature Conservancy of Hawaii owns the island that is protected as a national wildlife refuge.

A dozen visiting conservatory trustees from Louisiana were supposed to leave Saturday, but the only aircraft that can fly directly there needs an engine replaced. So they are stuck.

"They've been there a week and it's time to get off and they have commitments to move onto," Nature Conservancy Director Suzanne Case said.

Palmyra hosts an international research outpost, has electricity, cabins and plenty of supplies.

"They are taking it very well. They know that we are moving forward in a safe and calculating way to find an alternative aircraft to transport them," Palmyra Island worker Andres Lyons said.

At Honolulu International Airport, Pacific Air Charters is fitting a twin-engine Cessna with a removable 75-gallon fuel tank that will get the plane to Christmas Island -- 300 miles from Palmyra. The tank will be removed to ferry the visitors off Palmyra in two trips.

The plane needs two things to get to Palmyra Island: first long range capability and second propellers. The island has a coral runway, which is very tough on jet engines.

Pilot mechanic Rob Szabo said the biggest challenge so far has been Federal Aviation Administration rules.

"Anytime you modify an aircraft you have to do a lot of paperwork, and it has to be approved by the FAA -- a lot of i's to dot and t's to cross," Szabo said.

The mission could finish Thursday unless some of the people choose not to leave.