A Pakistani aircraft carrying 47 people issued a Mayday call before losing radar contact and crashing into a mountain, killing everyone on board, authorities said, as they began collecting DNA to identify victims.
None of those on board survived the accident, the airline's chairman said.
"There are no survivors, no one has survived," Muhammad Azam Saigol told a press conference late on Wednesday, about five hours after flight PK661 from Chitral to the capital, Islamabad, crashed near the town of Havelian, in Khyber-Pakhtunkhwa province.
The pilot of the ATR-42 turboprop aircraft contacted ground authorities after one engine failed and issued a Mayday call at 4:14 pm (1014 AEDT), Mr Saigol said.
Saigol said the ATR-42 aircraft had undergone regular maintenance and had in October passed an "A-check" certification, conducted after every 500 hours of flight operations.
"I think that there was no technical error or human error ... obviously there will be a proper investigation," he said.
Rescue teams have recovered the bodies of all 47 people on the flight.
Remains are being brought by helicopter to Islamabad, where DNA tests will be used to identify them.
The plane was carrying 42 passengers - including two Austrians and a Chinese national - besides five crew members.
The airline said the plane crashed about 125 km north of Islamabad. The region is one of the most popular tourist destinations in Pakistan.
"All of the bodies are burned beyond recognition. The debris is scattered," Taj Muhammad Khan, a government official based in Havelian, told Reuters.
Khan, who was at the crash site, said witnesses told him "the aircraft has crashed in a mountainous area, and before it hit the ground it was on fire".
Images shown on Pakistani TV channels showed a trail of wreckage engulfed in flames on a mountain slope.
Irfan Elahi, the government's Aviation Secretary, told media the plane suffered engine problems but it was too early to determine the cause of the accident.
The military said it had sent in troops and helicopters.
Junaid Jamshed, a well-known Pakistani pop star turned evangelical Muslim cleric, was on board, according to Ahmed, the PIA official in Chitral.
Jamshed, a singer in one of Pakistan's first successful rock bands in the 1990s, abandoned his singing career to join the Tableeghi Jamaat group, which travels across Pakistan and abroad preaching about Islam.
According to the flight manifest, there were three people on board with foreign names.
Plane crashes are not uncommon in Pakistan and safety standards are often criticised.
PIA has also suffered major disasters in the past.
With AFP, AAP