Pakistan International Airlines flight PK661 crashed on the slope of a mountain in northern Pakistan on Wednesday. Reuters

The pilot of the ill-fated Pakistan International Airlines plane that crashed in northern Pakistan Wednesday had made a mayday call shortly before the jet lost touch with the control tower, chairman of the PIA said. Flight PK-661 carried 48 people, including two Austrians and a Chinese national.

The small twin-propeller aircraft was flying from Chitral city to Islamabad. It crashed near Abbottabad, which is located about 75 miles northwest of the capital, at about 4:45 p.m. local time (6:45 a.m. EST).

Azam Saigol, the airlines’ chairman, said late Wednesday that an engine developed a technical glitch, after which the plane disappeared and the pilot made the distress call. The aircraft was fit to fly and it remains unclear what led to the technical fault.

The ATR turboprop aircraft had its regular maintenance done and passed an “A-check” maintenance certification, which is conducted after every 500 flight hours, Saigol said. Full investigation of the incident will be carried out with the help of international agencies, he added.

“In Pakistan, there is a big question regarding whether international safety standards are followed when it comes to aircrafts … In an emergency landing, a plane is supposed to land at the nearest place. Perhaps they did not have this choice... perhaps the plane was not in good flying condition. If the pilot is not able to sustain the flight of the plane then a crash is inevitable,” Pakistan air force official Shahid Latif said, according to reports.

The plane carried 42 passengers, five crew members and a ground engineer. Ambulance driver Duray Hussain reportedly said the remains of the victims were “beyond recognition.”

Among those deceased was popular singer-turned-Islamic-preacher Junaid Jamshed and his wife. The 57-year-old former pop singer was a member of one of Pakistan’s first successful pop and rock bands Vital Signs in the 1980s and 1990s. In 2004, he left his music career and joined the Tableeghi Jamaat group that traveled across the world to preach about Islam. On Wednesday, Jamshed was returning to Islamabad after attending a Tableeghi mission. In his last tweet, Jamshed praised Chitral’s beauty.

Pakistani Prime Minister Nawaz Sharif expressed grief and sorrow over the plane crash.

“The entire nation is deeply saddened over today’s unfortunate crash and shares the grief of the families who lost their dear ones,” Sharif said in a statement.

Pakistan has a fairly poor track record of air safety, which often comes under fire. There have been several reports of near-misses as planes overran runways and engines caught fire. In 2010, a passenger plane went down near Islamabad in heavy rain, claiming lives of all 152 people on board. After two years, a plane operated by a private Pakistani company crashed near the capital killing all 127 people on board.

In March 2007, the European Commission banned most of PIA’s planes due to safety concerns. The ban was partially lifted after four months and by November that year the ban was completely removed. In September 2014, the EU suspended PIA’s cargo services to the 28-nation bloc. However, the ban was entirely lifted after two months.