ASN Aircraft accident Boeing 737-236A AP-BKC Islamabad-Benazir Bhutto International Airport (ISB)
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Status:Accident investigation report completed and information captured
Date:Friday 20 April 2012
Time:18:40
Type:Silhouette image of generic B732 model; specific model in this crash may look slightly different
Boeing 737-236A
Operator:Bhoja Airlines
Registration: AP-BKC
MSN: 23167/1074
First flight: 1984-12-13 (27 years 5 months)
Total airframe hrs:46933
Cycles:37824
Engines: 2 Pratt & Whitney JT8D-15A
Crew:Fatalities: 6 / Occupants: 6
Passengers:Fatalities: 121 / Occupants: 121
Total:Fatalities: 127 / Occupants: 127
Aircraft damage: Destroyed
Aircraft fate: Written off (damaged beyond repair)
Location:4,2 km (2.6 mls) SE of Islamabad-Benazir Bhutto International Airport (ISB) (   Pakistan)
Phase: Approach (APR)
Nature:Domestic Scheduled Passenger
Departure airport:Karachi-Jinnah International Airport (KHI/OPKC), Pakistan
Destination airport:Islamabad-Benazir Bhutto International Airport (ISB/OPRN), Pakistan
Flightnumber:B4213
Narrative:
A Boeing 737-236 passenger plane, operated by Bhoja Airlines, was destroyed in an accident near Islamabad, Pakistan. All 121 passengers and six crew members were killed. Bhoja Airlines flight 213 departed Karachi (KHI) at 17:05 on a domestic flight to Islamabad (ISB). This was the inaugural evening flight for the airline on this route.
The flight climbed to a cruising altitude of FL310 and continued towards Islamabad. Weather at the destination was poor due to a passing thunderstorm. At 18:19 the captain at a distance observed the squall line. Moments later the flight was cleared to descend to FL200. During the descent the captain and first officer discussed the weather. They were worried about the severity of the thunderstorm ahead.
At 18:26 the first officer contacted Islamabad Approach and received clearance for the One Foxtrot arrival for an ILS approach to runway 30. After receiving further descent clearance the first officer discussed opportunities to approach the airfield through a gap in the squall line. The Approach controller gave radar vectors and descent instructions to fly through the gap in the storm.
At 18:35, Islamabad Approach gave a weather update and said "Bhoja 213 surface wind at Islamabad ah is varying between 180° to 270°, 10 kts and ah sometimes gusting to 20 kts and runway condition is wet, light drizzle is ah uhm going on, braking action not known".
Two minutes later the airplane entered the squall line. Although the Bhoja Air Operational Manual prohibited flight in these conditions, the captain decided to continue. The airplane was configured for the approach with flaps and slats selected and the undercarriage was down. The first officer then reported the speed to be 220 knots, which was 30 knots higher than the recommended speed. The captain reacted surprised as he did not expect this because the he was flying with the auto-throttle engaged. Likely the increase in speed was a result of windshear. The aircraft then entered the active weather cell with precipitation continuing in varying intensity. At 18:39 the airplane captured the ILS and descended on the glide slope. At this point the aircraft should have been in landing configuration with flaps at 30°. However, only flaps 5 were selected.
The aircraft then encountered an increasing downdraft. The pitch attitude increased and computed airspeed decreased as the autopilot attempted to maintain the glide slope. The GPWS consequently sounded with the aural alarm: "Wind shear - Wind shear - Wind shear". Although the first officer anxiously called for a go around, no action was taken.
The downdraft dissipated and the pitch attitude decreased but the aircraft deviated left of the extended runway centerline, and was brought back by the captain. At that moment the autopilot disconnected due to the aircraft deviation beyond the autopilot maximum authority limits. The auto throttle remained engaged in IAS speed mode. Following autopilot disconnect, there was no control wheel activity recorded for approximately 6 seconds and no control column activity for approximately 8 seconds. The crew were likely confused. During this period of control inactivity, the aircraft deviated below the glide slope.
Then the Terrain Awareness Warning System (TAWS) alarm sounded: "Whoop, Whoop, Whoop". No action was taken by either crew member. A few seconds later the aircraft entered another downdraft and the rate of descent increased rapidly. The TAWS alarm sounded again, directing the crew to "pull up". The captain responded with a nose-up column input. However, pressure altitude and thrust continued to decrease. The downdraft dissipated rapidly, resulting in a rapid increase in angle of attack of the aircraft, which activated the stick shaker for almost 2 seconds. It appeared that captain lowered the nose down to get out of stick shaker regime however, proper and complete Boeing recommended stall and recovery procedures were not carried out. This resulted in a 12° nose down pitch. Then another windshear alarm sounded, followed by another stick shaker activation. The first officer shouted to "get out" and "go around" but the attempts by the captain failed as he did not apply the proper procedures to execute a go around.
Shortly after initial ground contact, the aircraft struck a steeply sloped terrace about 5 meters high which resulted in significant structural breakup of the aircraft structure.

Probable Cause:

The ineffective automated flight deck management in extreme adverse weather conditions by cockpit crew caused the accident. The ineffective automated flight deck management was due to various factors including; incorrect selection of cockpit crew on account of their inadequate flying experience, training and competence level for Boeing 737-236A (advanced version of Boeing 737-200 series), absence of formal simulator training in respect of FO for handling an automated flight deck, non-existence of cockpit crew professional competence / skill level monitoring system at operator level (Bhoja Air).
The cockpit crew incorrect decision to continue the flight for destination and non-adherence to Boeing recommended QRH and FCOM remedial actions /procedures due to non-availability of customized aircraft documents (at Bhoja Air) for Boeing 737-236A (advanced version of Boeing 737-200 series) contributed towards the causation of accident. The inability of CAA Pakistan to ensure automated flight deck variance type training and monitoring requirements primarily due to incorrect information provided by the Bhoja Air Management was also a contributory factor in causation of the accident.

Accident investigation:

cover
Investigating agency: CAA Pakistan
Status: Investigation completed
Duration: 2 years and 9 months
Accident number: SIB-350
Download report: Final report

Classification:
Windshear/downdraft
Loss of control

Sources:
» NTSB
» SKYbrary 

METAR Weather report:
13:00 UTC / 18:00 local time:
OPRN 201300Z 23020KT 4000 TS FEW025CB SCT030 BKN100 25/15 Q1009.3/29.80

14:00 UTC / 19:00 local time:
OPRN 201400Z 23020KT 3000 TSRA FEW025CB SCT030 BKN100 20/16 Q1011.0/29.85


Photos

photo of Boeing-737-236-ZS-OLB
accident date: 20-04-2012
type: Boeing 737-236
registration: ZS-OLB
photo of Boeing-737-236-G-BKYI
accident date: 20-04-2012
type: Boeing 737-236
registration: G-BKYI
 

Aircraft history
date registration operator remarks
13 DEC 1984 G-BKYI Boeing first flight
07 JAN 1985 G-BKYI British Airways delivered
06 JUN 1999 ZS-OLB Comair delivered
JAN 2011 ZS-OLB Comair withdrawn from use and stored at Johannesburg (JNB)
FEB 2012 AP-BKC Bhoja Airlines bought

Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Karachi-Jinnah International Airport to Islamabad-Benazir Bhutto International Airport as the crow flies is 1119 km (700 miles).
Accident location: Approximate; accuracy within a few kilometers.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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Boeing 737-200

  • 1114 built
  • 123rd loss
  • 59th fatal accident
  • 5th worst accident
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 Pakistan
  • 2nd worst accident
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