ISLAMABAD Finding exact cause of the crash of Air Blue Airbus A321 over the Margalla hills on Tuesday would remain trickiest question until the plausible leads come to light from analysis of the data retrieved from the Black Box if found at all. Pakistans Civil Aviation Authority (CAA) said the pilot had been in contact with the control tower at the airport until just before the crash. In the last conversation with the control tower, the pilot had been given landing clearance and the plane was proceeding normally for landing before it crashed into the hills, CAA sources said. The Civil Aviation Authority said all possible causes would be investigated, including terrorism and bad weather, although officials gave no indication that an attack might have been to blame. Sources in the Air Blue said that there was no technical fault in the passenger plane that crashed in Margalla hills but there was possibility that the plane crashed due to inclement weather. Background discussions and interviews with technical experts revealed that since Pakistan had no facility to retrieve the data and electronically analyse it, the Black Box of the ill-fated plane would be sent abroad for that purpose. Sources were of the view that it would be a time consuming exercise and the concerned stakeholders might eventually lose the interest. However, some sources blamed the inclement weather amongst hosts of other factors as potential cause that might have led to the Air Blue Airbus A321 crash leaving the 152 people onboard dead. Weather factor Aviation experts opined that unless 'black box flight recorders were found, it simply would not be possible to determine what caused that crash. There are so many unanswered questions, sources said, adding that it could be a combination of many things. But they were of the view that bad weather could have contributed the role of a villain in that case. However, when contacted DG Met Office Dr Fakhar Zaman Chaudhry, he informed TheNation that there had been constant rain in Islamabad till 10 AM. He was of the view that the aeroplane could land during the rainfall as well. Fuel shortage Experts counting the potential causes also questioned whether the aircraft had enough fuel to divert to another airport. A plane should always carry enough fuel to reach its destination plus an allowance for circling and enough spare fuel to reach a nominated alternative airport. Karachi to Islamabad is around two hours flying time, and it is a possibility that the pilot might not have enough fuel for a round trip. But they should certainly have had enough to divert. Navigational error Was this a navigational error by the pilot? Some experts are of the view that the plane might have been circling before an attempt to land. If so, was this his first attempt? asked a source. Some eyewitnesses told this scribe on the crash scene that the pilot perhaps resorted to that last option to hit the rocky hill to avoid collateral damage in the populated areas located in the foothills of Margalla. Some sources were of the view that fatigue might have been the real cause of the crash as the deceased pilot Parvez Iqbal Chaudhry before flying from Karachi to Islamabad had also travelled from Turkey to Karachi. Technical failure Was there a problem with the planes navigational system? Many believed that the Airbus was such a plane with inbuilt system that did not hamper the working of the plane even during the rain. Some people have also suggested that the Air Blue has the policy to take risky lands. They try their best not to divert their flights to other cities as they have limited flights and the diversion can disturb their schedule, they alleged. They added that it was the reason that despite heavy rain in the twin cities, Air Blue did not divert its flight to Lahore or other cities and tried to land it in Islamabad. Similarly, some were of the view that the pilot of the said plane was advised to use another way that was over Murree Road and the attempt to change the route took the flight to Margallas where it hit the hill and crashed. It is yet to be seen whether the final report of the incident would be made public or not as previously the reports of plane crashes that had taken place in Multan and the other in the Kohat District were not made public.