Probe blames overloading for 2012 Sita Air crash

- SANGAM PRASAIN, Kathmandu
Probe blames overloading for 2012 Sita Air crash

Aug 28, 2013-

An investigation report of the 2012 Sita Air crash has blamed overweight aircraft for the disaster. The report made public on Sunday after 11 months stated that the plane’s takeoff performance was compromised with both passengers and cargo weight.

On Sept 28, a Dornier aircraft bound for Lukla slammed into the banks of the Manohara River in Bhaktapur shortly after takeoff from Kathmandu, killing all 19 on board.

According to the report, the aircraft takeoff weight was 5,914 kg, whereas the maximum takeoff weight allowed for the Lukla flight is 5,836 kg. The aircraft load sheet recorded a takeoff weight of 5,834 kg, but this figure did not include an allowance for baggage.

The report said that a 2 kg underload was recorded on the load sheet of the aircraft, but did not account for the 70 to 80 kg of baggage it had on board. The investigation was

unable to verify the actual weight of the baggage on board the aircraft,

but the airline stated that the aircraft was dispatched with an overload of up to 80 kg.

The report said that the inspection by a European travel company in 2011 recorded three miscalculations in the load sheets it assessed, all in the sense of recording a lower traffic load than was actually the case. It also noted that several flights were found have departed, manipulating the maximum takeoff weight, for example mentioning only 1kg intead of actual load of 23 kg.  

The report said that the airline procedure assumes a traffic load of 15 passengers, made up of five Nepalis and 10 foreigners, for flights from Kathmandu to Lukla.

“Using the investigation’s assumptions about their gender, this represents a traffic load of 1,305 kg whereas the total traffic load allowed is 1,152 kg,” the report reads.

Flights cannot dispatch under these circumstances for the short takeoff and landing (STOL) operations to Lukla.

Based on witnesses, the report said that a handbag registered 15 kg when it was put on the scales at Kathmandu airport check-in was actually 11 kg at Lukla airport.

According to the report, the stall warning was triggered for nine of the final 11 seconds of the flight, initially when the aircraft was level and decelerating through 131 km/h (71 knots), and then as the aircraft decelerated to 127.78 km/h and began to descend.  It climbed approximately 100 ft before flying level.

The flight crew made an unsuccessful attempt to rotate the aircraft at approximately 129.64 km/h. The aircraft drifted to the left of the runway, probably because the left engine was delivering less power than the right, the report said.

According to the report, overloading alone was not the cause of the lack of performance in the climb phase and stated that the aircraft must have lost power.

At 6:13 am, the co-pilot asked Air Traffic Controller (ATC) for clearance. After lining up for takeoff, the captain said, “There is a bird,” and three seconds later, “I will take flaps two,” which was acknowledged by the co-pilot.

The aircraft was cleared for departure and began its takeoff roll. Two seconds after beginning the takeoff roll, the captain said, “Watch out for the bird.”  

Two seconds later, the co-pilot called, “Bird clear, sir,” as the aircraft accelerated through 107.41 km/h. As the aircraft began to climb, it accelerated to 164.82 km/h over 2 seconds. As the aircraft continued to climb above the runway, the speed decreased to 142.60 km/h and subsequently dropped to 127.78 km/h.

According to the report, the ATC asked, “Any technical,” to which the pilot replied, “Uncertain… bird hit.” The aircraft began a gentle descent at 127.78 km/h with the stall warning sounding and the rate of turn to the left increased rapidly.  

The aircraft stalled and crashed 420 m to the southeast of the threshold of Runway 02. The aircraft hit the ground in a near vertical attitude with its upper surface facing towards the northwest, but with some horizontal speed towards the southeast.

A runway inspection found the remains of a bird, identified as a black kite, at a position 408 m from Runway Intersection 2.  

Witnesses at the ATC tower reported that the aircraft raised and then lowered its nose during the takeoff run. It left the ground near Intersection 5 and climbed straight ahead, but the climb was not normal, and the climb speed seemed to the witnesses to be very low.

The nose was raised from the ground quite suddenly and the tail almost hit the runway before the nose was lowered again.

A CCTV camera on an airport building recorded that 5 seconds before the aircraft left the ground, a flash appeared in the region of the right engine.

The post-mortem report shows the impact was not survivable, and all the occupants within the aircraft received fatal injuries during the impact sequence before the aircraft caught fire.

The crash investigation commission issued a number of interim safety recommendations to the government on Nov 29, 2012 including regular calibration of the weighing machines at the check-in counters at all the airports.

It has also recommended to the Civil Aviation Authority of Nepal (CAAN) to review the suitability of the average weights used for passengers on flights within Nepal and modify them if necessary.

The maximum permissible weight of a foreign passenger has been revised to 90 kg from the previous 75 kg. The weight for a Nepali passenger has been fixed at 75 kg, up from the previous 70 kg.

The Civil Aviation Ministry published the report on its website in its bid to be more transparent amid criticism over the handling of air accident reports, said Buddhi Sagar Lamichhane, joint-secretary at the ministry’s Aviation Safety Division. “We will not compromise on safety oversight.”

Hence, a number of safety recommendations, including weight specification, was immediately imposed by CAAN and is in process to impose other recommendations, Lamichhane said.

Published: 29-08-2013 10:16

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