A man walks past the Trigana Air Services logo at the airlines office in Jakarta August 16, 2015 in this photo taken by Antara Foto. [Photo/Agencies]

MONTREAL/TORONTO - Indonesia scored poorly on a 2014 safety audit by the United Nations' aviation agency largely because its Ministry of Transportation is understaffed, said two sources familiar with the matter, as the country struggles to cope with the rapid expansion of air travel.

Indonesia's patchy aviation safety record worsened on Sunday when a passenger plane crashed in eastern Papua province with 54 people aboard, the third major plane crash this year in the Southeast Asian archipelago.

The UN's Montreal-based International Civil Aviation Organization (ICAO) sets safety standards for international flights. Its audits evaluate countries' ability to oversee their airlines, including how well they conform to those standards.

Indonesia's government has struggled to hire and train staff quickly enough to oversee its fast-growing aviation market, which the International Air Transport Association expects to triple in size by 2034.

"Until they resolve this they cannot do the same level of supervision and certifications as a country with a robust system in place," one of the sources said.

Since the 2014 audit, Indonesia has come up with a plan to address its problems, the source said.

"They have been very active in developing their plan," the source said. "They are making progress."