DAVAO—A US Navy vessel has arrived to help search for the wreckage of a Philippine military transport plane that crashed at sea off Davao del Norte’s Samal Island, an official said Tuesday.

The oceanographic survey ship USNS John McDonnell arrived in the Davao Gulf on Monday for a two day mission to help search for the C-130 aircraft that went down on August 25, killing all nine people on board, Philippine Navy Captain Rosauro Arnel Gonzales said.

Gonzales, head of a special task force for the recovery of the plane, said that so far there were no reports on whether the US vessel had spotted the wreckage.

The crash site still has not been located and officials believe the plane is in deep water, beyond the reach of Philippine divers. It is hoped that the US vessel may have the equipment to locate it, he said.

The 41-year-old US-made aircraft lost contact with air traffic controllers shortly after taking off from Davao airport on restive Mindanao island last month.

Only debris was found floating in the waters off the island.