ISLAMABAD: The Civil Aviation Authority (CAA), on Saturday, issued a preliminary investigation report on the Bhoja Air plane crash near Islamabad and promised to make the full report public, according to DawnNews.

Speaking at a press conference, the Director General of CAA Captain Nadeem Yousufzai said the black box, which records flight data, was recovered by rescue officials last night and will be dispatched to the United States for investigation.

The black box will be handed over to Boeing, manufacturers of the Boeing-737 aircraft that crashed last night, who will then perform the investigations.

Yousufzai told reporters that the investigation may get completed within a month's time, but the final result of the inquiry could take up to a year to become evident.

According to the preliminary report revealed by CAA, three minutes before the crash, the plane’s captain had informed the control tower that the plane was getting out of his control. The fuel tank of the plane had exploded as it approached the runway, the report added.

The plane was flying at the altitude of 2,000 metres when it last contacted the control tower.

At a press conference on Saturday, Nadeem Khan Yousafzai, director-general of Pakistan's Civil Air Authority, said the plane was locked into the instrument landing system, an approach system that provides precision guidance for aircraft, when it suddenly dropped from 2,900 feet to 2,000 feet.

“ It just went down, into a dive ,” he said. “Then contact was lost and the blip disappeared from the radar.”

“What happened in this period, that has to be investigated. Was there a downdraft, was there an engine failure?”

Minutes prior to its planned landing at the Benazir Bhutto International Airport, the plane had been descending at a speed of 500 kilometres per hour before it eventually crashed, the report revealed.

The officials on Saturday promised a full investigation into the crash of a domestic flight that killed 127 people, saying they were examining all possibilities, from a technical fault to the age of the Boeing 737.

Military and aviation officials said bad weather was probably behind the crash, as there was a hail and thunderstorm over the city at the time.

A senior PIA engineer told AFP the age of the aircraft mattered less than its flying hours, and said he thought an air pocket -- a patch of low air pressure -- could be to blame.

“Since it was approaching the airport to land it was obviously flying low -- between 3,000 and 4,000 feet above the ground,” he said.

“Visibility was also low because it was raining and there was thunder and lightening. The pilot lost control and apparently failed to lift it out of the air pocket.”

The Boeing 737-200 was more than 27 years old, according to AviationSafety.net.

The Bhoja Air passenger jet crashed on Friday as it tried to land in a thunderstorm at Islamabad’s main airport, killing all 127 people on board. The small domestic airline, which resumed operations in March after an 11-year pause, had said the weather was the cause.

Bhoja Air started domestic operations in Pakistan in 1993 and eventually expanded to international flights to the United Arab Emirates in 1998. The company suspended operations in 2001 due to financial difficulties but resumed them in 2012.