Indonesian search and rescue teams are heading to a remote part of the western Papua region where a plane is believed to have crashed on Sunday.
Officials have confirmed they spotted debris near the town of Oksibil.
The Trigana Air flight was heading to the town from the provincial capital, Jayapura, when it lost contact at 14:55 local time (05:55 GMT) on Sunday.
The plane was carrying 44 adult passengers, five children and infants, and five crew members.
It is not yet known if anyone survived.
Indonesian post office officials told the BBC the plane was also carrying four bags containing about 6.5 billion rupiah ($486,000; £300,000) in cash, which was being taken to villages in remote areas.
"Our colleagues carry those bags to be handed out directly to poor people over there," said the head of Jayapura's post office, Haryono, who goes by only his first name.
The head of Indonesia's national search and rescue agency, Bambang Soelistyo, said a search plane had spotted suspected debris and billowing smoke at 8,500 feet above sea level, about 50km (31 miles) from Oksibil Airport.
About 50 search and rescue workers, soldiers, and policemen are making their way from Oksibil to the site.
The ATR42-300 twin turboprop plane took off from Sentani airport in Jayapura at 14:21, but lost contact with air traffic controllers half an hour later.
Bad weather is believed to have been a possible reason for the crash. A search plane was forced to turn back on Sunday because of dangerous flying conditions.
Villagers had earlier told officials that a plane had crashed into a mountain.
Bad weather and rugged terrain are said to be hampering efforts to reach the site.
Oksibil, which is about 280km south of Jayapura, is a remote, mountainous region, which is extremely difficult to navigate.
Indonesian President Joko Widodo has expressed his condolences on Twitter and called for the country to "pray together" for the victims.
Trigana Air has had 14 serious incidents since it began operations in 1991, losing 10 aircraft in the process, according to the Aviation Safety Network.
It has been on a European Union blacklist of banned carriers since 2007. All but four of Indonesia's certified airlines are on the list.
Indonesia has suffered two major air disasters in the past year.
Last December an AirAsia plane crashed in the Java Sea, killing all 192 people on board - and in July a military transport plane crashed in a residential area of Medan, Sumatra claiming 140 lives.