(CNN) -- All 13 people aboard a small plane that crashed in Papua New Guinea were killed, the airline said Wednesday.
The twin-engine plane took off Tuesday from the capital, Port Moresby, for a 27-minute flight to Kokoda, a popular destination for tourists who want to hike a mountainous trail by the same name.
The plane was carrying two "highly experienced" Papua New Guinean pilots and 11 passengers -- nine Australians, a Japanese and a Papua New Guinean, according to Airlines PNG.
Air traffic controllers lost contact with the flight as it flew through thickly forested mountains Tuesday morning.
The next day, wreckage of the Twin Otter turboprop was spotted at an altitude of 5,500 feet (1,676 meters) in the mountains -- with no survivors, Airlines PNG said.
Authorities could not immediately say what had caused the crash.
The plane had recently been fitted with new navigation equipment, and the pilots were familiar with the route, "having both flown in Papua New Guinea for approximately five years on this aircraft type," the airline said.
"Earlier in the day, an Airlines PNG flight had operated into Kokoda under normal weather conditions, but conditions in the mountainous terrain can be subject to sudden changes," the airline said.
The eight Australians were flying to Kokoda to walk the trail.
"There is a horrible tragedy involved when families send off their loved ones for what they expect to be the experience of a lifetime, only for it to turn into a tragedy such as this," Australian Prime Minister Kevin Rudd told Parliament on Wednesday.
Australia sent three helicopters and two planes to help with the search and rescue effort.
Rudd has hiked in the single-file 60-mile (96-kilometer) mountainous pass.
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