Three Cambodian aviation experts will fly to China on Saturday carrying the black box of a Chinese-made Z-9 military helicopter that crashed in a Phnom Penh quarry on Monday, killing four.

Air Force commander Soeung Samnang said a joint commission of inquiry was sending the black box to a Chinese manufacturer for review.

Chinese experts will continue to scour the crash site, interview witnesses and search for evidence to determine exactly what caused the helicopter to go down, he said.