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B732, vicinity Islamabad Pakistan, 2012

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Summary
On 20 April 2012, the crew of a Boeing 737-200 encountered negative wind shear during an ILS final approach at night in lMC and failed to respond with the appropriate recovery actions. The aircraft impacted the ground approximately 4 nm from the threshold of the intended landing runway. The Investigation attributed the accident to the decision to continue to destination in the presence of adverse convective weather and generally ineffective flight deck management and noted that neither pilot had received training specific to the semi-automated variant of the 200 series 737 being flown and had no comparable prior experience.
Event Details
When April 2012
Actual or Potential
Event Type
Human Factors, Loss of Control, Weather
Day/Night Night
Flight Conditions IMC
Flight Details
Aircraft BOEING 737-200
Operator Bhoja Air
Domicile Pakistan
Type of Flight Public Transport (Passenger)
Origin Karachi/Jinnah International Airport
Intended Destination Islamabad/Benazir Bhutto International Airport
Take off Commenced Yes
Flight Airborne Yes
Flight Completed No
Flight Phase Descent
ENR / APR
Location - Airport
Airport vicinity Islamabad/Benazir Bhutto International Airport
General
Tag(s) Approach not stabilised,
Inadequate Aircraft Operator Procedures,
Ineffective Regulatory Oversight,
Deficient Crew Knowledge-systems,
Deficient Crew Knowledge-handling
HF
Tag(s) Authority Gradient,
Inappropriate crew response - skills deficiency,
Ineffective Monitoring,
Manual Handling,
Plan Continuation Bias,
Procedural non compliance,
Ineffective Monitoring - PIC as PF
LOC
Tag(s) Flight Management Error,
Flight Control Error"Flight Control Error" is not in the list (Airframe Structural Failure, Significant Systems or Systems Control Failure, Degraded flight instrument display, Uncommanded AP disconnect, AP Status Awareness, Non-normal FBW flight control status, Loss of Engine Power, Flight Management Error, Environmental Factors, Bird or Animal Strike, ...) of allowed values for the "LOC" property.,
Environmental Factors
WX
Tag(s) En route In-cloud air turbulence,
Low Level Windshear
Safety Net Mitigations
Malfunction of Relevant Safety Net No
TAWS Available but ineffective
Outcome
Damage or injury Yes
Aircraft damage Hull loss
Non-aircraft damage Yes
Fatalities Most or all occupants ()
Causal Factor Group(s)
Group(s) Aircraft Operation
Safety Recommendation(s)
Group(s) Aircraft Operation
Investigation Type
Type Independent

Description

On 20 April 2012, a Boeing 737-200 (AP-BKC) being operated by Bhoja Air on a scheduled domestic flight from Karachi to Islamabad as BHO 213 failed to complete a night ILS approach to destination in adverse Instrument Meteorological Conditions (IMC) weather and the wreckage of the aircraft was subsequently found approximately 4nm from the threshold of the intended landing runway on the extended centreline of the intended landing runway. The aircraft was completely destroyed by ground impact and all 127 occupants were killed.

Investigation

An Investigation was carried out by the Pakistan CAA Safety Investigation Board. The wreckage of the completely destroyed aircraft was found 4.2 nm from the runway 30 threshold, with no signs of a post impact aircraft fire present. There was minor property damage in the vicinity of the impact site but there were no ground casualties. The FDR and CVR were recovered and subsequently were successfully downloaded by the NTSB.

The prelude to the accident was reconstructed on the basis of the available evidence. It was established that on departure from Karachi, with the commander as PF, the forecast for Islamabad was for a thunderstorm with gusting winds. There was also an off duty male member of Company cabin crew occupying the flight deck supernumerary seat in order to return to their home base. It was noted that the flight had been Bhoja Air's first evening flight on the route, with the possibility that this fact may have predisposed the commander against a weather-related diversion.

The flight proceeded en route at FL310 without encountering any operational or maintenance abnormality and there was discussion between the pilots on Lahore as first alternate and Peshawar as the second as well as evidence of their full awareness of the overall prevailing weather situation. As the flight progressed, a squall line was observed ahead on the weather radar and it was noted that there were few if any obvious gaps in it. However, no other area of adverse weather was apparent.

Lahore Approach cleared the flight to descend to FL200 on track and then transferred it to Islamabad Approach Radar which, after radar identification, gave descent to 9500 feet to initially follow a designated STAR but to expect radar vectors to an Instrument Landing System (ILS) approach to Runway 30 at Islamabad. Further descent clearances, eventually to an altitude of 3600 feet (approximatelty 1650 feet aal), followed. During descent, some turbulence was experienced but no adverse weather was encountered and there was no effect on flight path management with the AP and A/T engaged. As the aircraft received radar vectors, some lightning was seen and it appeared that the squall line was running approximately east-west across the general vicinity of the destination as the aircraft approached from the south.

With the AP engaged and the aircraft level at 3600 feet, the ILS LOC was captured at about 6nm from touchdown. Twenty seconds later, with both APs now engaged, the ILS GS was also captured by which time the aircraft was configured with the landing gear down but with only flap 5 rather than the SOP flap 30 selected. By this point, there was evidence that the aircraft was already in 'moderate' precipitation and turbulence and within the extent of the adverse weather indicated over the airport on radar. As the GS was captured, a sudden short downdraft was encountered, following which recorded data indicated that the precipitation being flown through had suddenly changed from 'moderate' to 'extreme'. After just a few seconds, a second sudden and much more severe downdraft occurred which triggered a reactive wind shear warning from the EGPWS as 1000 feet of altitude was lost in 4 seconds to bring the aircraft to 900 feet agl. No crew response was evident except calls from the First Officer to go around. As this downdraft moderated, both AP channels recorded disconnect. There was a delay in the take over of manual control and descent, with the aircraft now well below the ILS GS, continued with the A/T still engaged and set to hold 170 knots.

As a second severe downdraft was then entered and two successive EGPWS 'PULL UP' Warnings occurred without the prescribed response from the crew. Then, as this downdraft dissipated quite suddenly, the increase in angle of attack led to a short activation of the stick shaker/stick pusher which was followed by only a pitch down input and, notably, a reduction in thrust which had already been reduced. A further brief stick shaker activation then occurred followed after a few seconds by the beginning of 6 seconds of PULL UP Warnings which ended with impact in approximately level attitude at high speed with both engines operating normally. Twenty seconds before impact, the aircraft had checked in with TWR on transfer from APP Radar but the crew had not acknowledged a landing clearance issued shortly afterwards.

It was noted that "the weather conditions at the time of the accident were conducive to producing strong downdrafts and wind shear like conditions" and that surface weather reports at Islamabad had confirmed this. A simulation by Boeing using the FDR data was able to show that the aircraft flight path could be attributed to a combination of the recorded flight control inputs and the prevailing atmospheric conditions and that the "ineffective management of thrust, altitude and flight path in turbulent atmospheric conditions resulted in ground impact short of the runway" which would have been avoidable had the appropriate responses to the wind shear, pull up and stall warnings occurred. It was also considered that prior to the encounter with adverse weather, "it was evident from the Captain’s remarks (recorded on the CVR) that he had made up his mind to land at (Islamabad) irrespective of prevalent weather conditions during approach".

It was found that the aircraft type training of both pilots had been inadequate and that in particular, the Operator had taken insufficient account of both the nature and extent of their previous experience in respect of the significant differences in the level of automation between the 'basic' 737-200 variant with which they were familiar and the '-236Advanced' variant which they had been flying on the day of the accident. Their "ineffective management of thrust, altitude, and flight path...despite knowing the associated dangers while operating aircraft into such a weather phenomenon" was attributed to this context. In addition, it was considered that as the commander got into increasing difficulty, the First Officer had lacked "the system knowledge, experience and confidence" to intervene which had previously career-limited his rank.

The formal Conclusion of the Investigation was that the accident was caused by “the ineffective automated flight deck management by the pilots in extreme adverse weather conditions”. It was considered that this was the result of various Contributory Factors including:

  • inappropriate selection of the pilots as fit to operate on account of their inadequate experience of the aircraft variant being flown
  • lack of training and competence assessment for the -236A, an advanced version of Boeing 737-200 series
  • absence of formal simulator training for the First Officer in the handling of an automated flight deck
  • absence of a flight crew professional competence / skill-level monitoring system at Bhoja Air

Other Contributory Factors were identified as follows:

  • the incorrect decision of the flight crew to continue the flight to the planned destination given their awareness of adverse conditions ahead
  • non-adherence to Boeing recommended QRH and FCOM remedial actions/procedures due to the non-availability of aircraft documents customised for the Boeing 737-236A, an advanced version of Boeing 737-200 series
  • the inability of the Pakistan CAA to ensure automated flight deck variance type training and monitoring requirements primarily due to incorrect information provided by Bhoja Air
  • poor overall management of flight operations at Bhoja Air

A total of twenty three Safety Recommendations were made as a result of the Investigation as follows:

  • that the CAA Pakistan should ensure that Flight Standard Inspectors monitor 100% of both initial and recurrent pilot simulator training.
  • that the CAA Pakistan should strictly monitor pilot proficiency along with their recurrent training compliances at operator level.
  • that the CAA Pakistan should ensure strict compliance of their directives / instructions by all operators.
  • that the CAA Pakistan should devise a mechanism for close monitoring / tracking of simulator training waivers / extensions for pilots.
  • that the CAA Pakistan should ensure that an operator has available all customised / applicable aircraft documentation before issue / approval of operations specifications.
  • that the CAA Pakistan should require the submission by Operators of a compliance report prior to the formal start of flying duties by pilots.
  • that the CAA Pakistan should require the submission by Operators of a compliance report in respect of the completion of aircraft variance type ground and simulator training prior to the formal start of flying duties by pilots.
  • that the CAA Pakistan should implement 100 % coverage of aircraft inspections in respect of new inductions / registrations by Flight Standards Inspectors who possess a type rating on the specific aircraft.
  • that the CAA Pakistan should implement the inclusion of wind shear, TAWS (EGPWS) and stall recovery exercises as mandatory items in the Pilot proficiency Check (PPC) during simulator training sessions.
  • that the CAA Pakistan should review the Licensing Circular (ASC) –1 / 2000 (issue one) dated 15 October, 2000 for inclusion of Boeing 737-236A aircraft variance type training.
  • that the CAA Pakistan should devise a mechanism for the strict monitoring / performance evaluation of pilots at newly-launched Operators.
  • that the CAA Pakistan should formally certify flight crew schedulers to ensure that they possess the required level of competence.
  • that the CAA Pakistan should mandate serviceability of EGPWS / GPWS / TAWS /Wind shear warning system (predictive or reactive) for all turbine-engined aeroplanes of a maximum certified take off mass in excess of 5700 kg or authorized to carry more than nine passengers, in the MEL of all operators.
  • that the CAA Pakistan should progress the availability and integration of a Low Level Wind Shear (LLWS) warning system with Automatic Weather Observation System (AWOS) at all airports.
  • that the CAA Pakistan should review the existing procedure for the issue of a Certificate of Airworthiness (C of A) and its validation by competent authority.
  • that the CAA Pakistan should progress the implementation of automated flight crew scheduling system by all operators.
  • that the CAA Pakistan should ensure that all operators submit their pilot selection and induction procedures / policy for formal approval by the CAA.
  • that the CAA Pakistan should require that regular flight safety meetings are held by Operators and their proceedings submitted to the CAA.
  • that all Operators in Pakistan are to ensure that they provide (appropriately) customised directly applicable aircraft documents for the approval of CAA Pakistan prior to the launch of flying operations.
  • that all Operators in Pakistan are to ensure that Operations Manual Procedures are strictly implemented by their pilots.
  • that all Operators in Pakistan are to ensure the completion of aircraft type variant ground and simulator training for pilots and then submit a corresponding compliance report to the CAA prior to the formal start of flying duties by pilots.
  • that all Operators in Pakistan are to re-emphasise to pilots the importance of strict compliance with Operations Manual, FCOM and QRH instructions / Original Equipment Manufacturer (OEM) recommendations.
  • that all Operators in Pakistan are to devise a mechanism where pilots share their views freely with appropriate supervisory levels in order to highlight deficiencies in their training which could affect the safe conduct of flights.
  • that all Operators in Pakistan are to devise a mechanism for the close monitoring / tracking of simulator training waivers / extensions for pilots.

The Final Report was released on 21 January 2015.

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