By Simon Hradecky, created Wednesday, Dec 7th 2016 12:18Z, last updated Friday, Sep 11th 2020 17:21Z A PIA Pakistan International Airlines Avions de Transport Regional ATR-42-500, registration AP-BHO performing flight PK-661 from Chitral to Islamabad (Pakistan) with 42 passengers and 6 crew, reported the failure of the left hand engine (PW127E). The crew shut the engine down and continued towards Islamabad descending, some time later declared Mayday, shortly afterwards radio and radar contact was lost with the aircraft at about 16:16L (11:16Z). Residents in Havelian near Abbottabad (Pakistan) heard sounds consistent with an impact. The crash site was located at that position about 25nm north of Islamabad, the wreckage was ablaze with a plume of smoke over the crash site. All occupants of the aircraft perished in the crash.



The airline reported contact with flight PK-661 has been lost, all resources have been mobilized to locate the aircraft. The airline reported there were 42 passengers (including 2 infants, 2 Austrian and 1 Chinese Citizen), 3 flight crew, 2 cabin crew and a mechanics on board of the aircraft.



In the evening the airline confirmed that AP-BHO had crashed near Havelian.



In the evening of Dec 7th the airline reported in a press conference that the crew had been handed off from Cherat to Islamabad Air Traffic Control at 16:09L, at 16:14L the crew reported engine problems and began a descent, at 16:15L the crew declared Mayday, at 16:16L contact with the aircraft was lost. The aircraft was unable to maintain heading and turned left before impact with the ground.



Pakistan's Civil Aviation Authority (CAA) confirmed the aircraft declared emergency reporting engine trouble shortly before it disappeared from radar screens. Later the day the CAA reported that there had been no survivors, all bodies and the black boxes were recovered.



The Aviation Herald received information - contradicting a number of media reports in Pakistan - that the aircraft departed Chitral without any mechanical defect, no minimum equipment list requirements were in effect.



The blackboxes have been recovered and have been handed to Pakistan's Civil Aviation Authority.



On Jan 11th 2019 Pakistani TV Station DunyaNews showed what they claim is a safety recommendation released by Pakistan's SIB (Editorial note: the document as shown does not reveal an official letter head nor does it reveal a date, see below, there is no reference to this document on the CAA Pakistan's website) which appears to provide a first clue as to what caused the mechanical failure of the engine (but does not explain why the aircraft impacted terrain). The document reads in the factual part:



On 07 Dec 2016, a PIAC aircraft ATR (AP-BHO) flying from Chitral to Islamabad crashed near Havelian by killing all 47 souls on-board. Safety Investigation Board (SIB) of Pakistan was mandated by the Federal Govt to carry out detailed investigation into this unfortunate air crash.



The investigation is towards a concluding stage, however, some important findings of technical nature require immediate attention/intervention.



These are as follows:



(a) Sequence of events was initiated with dislodging of one blade of Power Turbine Stage-1 (PT-1), inside Engine No 1 (left-side engine) due to fatigue.



(b) This dislodging of one blade resulted in in-flight engine shut down, and it contributed towards erratic/abnormal behavior of No 1 Propeller.



(c) According to a "Service Bulletin" these turbine blades were to be changed after completion of 10,000 hrs. on immediate next maintenance opportunity. The said engine was under maintenance on 11 Nov 2016, at that time these blades had completed 10004.1 hrs (due for a change). This activity should have been undertaken at that time, but it was missed out by the concerned.



(d) Aircraft flew approximately 93 hrs after the said maintenance activity, before it crashed on 07 Dec 2016.



(e) Missing out of such an activity highlights a lapse on the part of PIAC (Maintenance and Quality Assurance) as well as a possible in-adequacy/lack of oversight by PCAA.



On Sep 8th 2020 Pakistan's Supreme Court instructed Pakistan's AAIB to submit the final investigation report by Oct 15th 2020 at the latest.



On Sep 11th 2020 Pakistan's Parliament was informed that the accident was caused by technical factors and was not caused by human error.



The document shown (Photo: DunyaNews TV):





Recovery works lasting into the night (Photo: Aamir Qureshi/AFP):





Crash site seen from Havelian (Photo: Malik Zubair Awan):





Map (Graphics: AVH/Google Earth):







