Pakistan International Airlines (PIA) announced Thursday it is "ready to pay compensation" of Rs5 million to the legal heirs of passengers who were killed in the PK-661 crash near Havelian on Dec 7, 2016.

PIA flight PK-661 carrying 48 passengers and crew crashed on the way to Islamabad from Chitral last year with no survivors. An investigation is underway to determine the cause of the crash.

Keeping in compliance with the requirements of the Carriage by Air Act 2012, PIA said in a statement that the amount of Rs5m is exclusive of the "interim/advance payments in the amount of Rs500,000 paid to each bereaved family".

Legal heirs claiming compensation for the loss of their loved ones will be paid as soon as they bring succession certificates and where applicable, guardianship certificates regarding property of the minor(s) legal heirs of the deceased and any other relevant documents, the statement added.

The Civil Aviation Authority (CAA) on January 12 had shared its findings from the black box data recovered from flight PK-661.

CAA Secretary Irfan Elahi had revealed that one of the plane's engines was working when the plane crashed, but black box data indicated that no effort was made to land the aircraft before the crash was reported.

Elahi had also said investigations are still ongoing to determine why the plane crashed despite one of its engines being functional.

Sharing details of the black box report, the CAA secretary had said the first call to the control room was made at 4:12pm, and the pilot's voice was seemingly "calm" when he made the call.

Two minutes later, at 4:14pm, the pilot issued a May Day call, saying one of the engines had stopped working.

At 4:17pm, the plane altered its course east instead of heading south, at which point the control room tried to get in touch with the pilot.

The last communication with the pilot was recorded at 4:17pm.

"Ten to 15 minutes later, the plane was reported to have crashed," Elahi revealed.

He said the data from the black box is a "100 per cent" unaltered, and that the investigation was conducted independently, without any involvement of the CAA or PIA.