Philippines medical helicopter missing with five on board

A search was underway in the Philippines on Wednesday for a missing medical evacuation helicopter with five people on board, authorities said.

The aircraft was flying a patient from the remote Mangsee Islands to a hospital on the western island province of Palawan, the Civil Aviation Authority of the Philippines (CAAP) said.

It took off on Wednesday morning to Brooke's Point municipality, but never arrived, CAAP said. Most of the 150-kilometre journey is over the Sulu Sea.

The Philippine Coast Guard said it had deployed a vessel to search waters between Balabac island, off southern Palawan, and Brooke's Point. The nationalities of those on board have not been released.

The helicopter was operated by the Philippine Adventist Medical Aviation Services, a non-profit organisation providing medical evacuation services in Palawan, the southern island of Mindanao and the main island of Luzon.

The group was started by American helicopter and fixed-wing pilot Dwayne Harris in 2007 and has five pilots and five aircraft, according to its website.

It describes itself as an "independent ministry that supports the mission of the Seventh-day Adventist Church."

Less than two weeks ago, a Cessna plane carrying four people, including two Australians, crashed on an active volcano in the central Philippines. All four died.