Sita Air plane crash ‘may be due to overload’: Report

A Sita Air twin prop aircraft that crashed killing all the passengers on board last September could have been overloaded, a report – after 11 months – into the accident revealed today.

The twin-engine propeller Dornier D-228 en route to Mt Everest crashed shortly after take-off in Kathmandu, last September killing 19 passengers on board – including Nepalis, Chinese and Britons – in the inferno when it ploughed into Manahara riverbank minutes after take off.

The report also revealed that the plane’s takeoff performance was compromised with both passengers and cargo weight.

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

The load sheet of the aircraft records a 2 kg underload but did not account for the 70 to 80 kg of baggage it had on board, it said, adding that the investigation was though unable to verify the actual weight of the baggage on board, it was dispatched with an overload of some 80 kg.

It also revealed that although the ‘load sheet’ – where crew record baggage on the flight – said there was no luggage, surveillance videos showed luggage being put on the plane. But it said that, although the overload could have been a factor, it could not be the sole cause of the crash. “It lost power and slowed down at a crucial point during take-off but investigators were unable to find why it happened. It meant the plane was not high enough to recover when it went off course.

According to the report, the crew also reported a bird strike before it crashed just two minutes after take-off and burst into flames.

The report also records that while preparing for take-off at 6.13 am, the pilot twice noticed a bird and as the plane accelerated, he said ‘watch out for the bird’.

The first officer reported being clear of it as he accelerated but the crew later reported a bird strike. However, no evidence of it was found in the engine.
“It is possible that the bird momentarily disturbed the air flow into the engine before it was struck by the propeller, causing a surge and the suspected flame seen in the CCTV footage, but the engine manufacturer considered it unlikely,” the investigators said, adding that the CCTV camera on an airport building has recorded a flash in the right engine five seconds before the aircraft left the ground. “If the flame seen in the CCTV and accompanying ‘bang’ heard on the CVR were evidence of an engine surge, then another possible cause is a fuel flow problem.”
As the plane turned, it lost power and began to descend, before suddenly hitting the ground just 420 metre from the runway.

The report also stated that one engine failed and the other suffered a power loss. The engine was also operating at low power.
“There was no evidence to suggest that the flight crew recognised that a power loss had occurred on the ground, possibly because it occurred gradually and progressively rather than instantaneously,” the report said, adding that it would account for why the takeoff was continued.

The report concluded that there was no evidence of a bird in the engine, both engines were low on power and when speed fell, there was no power to accelerate. “The investigation was unable to determine the cause of the thrust reduction,” it added.

The tragedy had been blamed simply on the plane striking a bird of prey at a height of 50-ft as it took off from Tribhuvan International Airport (TIA). But experts doubted whether that alone would have prevented the pilot from bringing the Sita Air Dornier D-228 back around for an emergency landing at the airport.

Meanwhile, the crash investigation commission on November 29, 2012 issued a interim safety recommendations to the government including regular calibration of the weighing machines at the check-in counters at all the airports. It has also recommended Civil Aviation Authority of Nepal (CAAN) to review the suitability of average weights for passengers on flights within the country and modify them if necessary.

The maximum permissible weight of a foreign passenger has been revised upwards to 90 kg from earlier 75 kg, according to the recommendation that has increased the weight for a Nepali passenger also to 75 kg, up from earlier 70 kg.

Ministry of Civil Aviation and Tourism has published the report on its website too, as in the recent years air safety has become a serious issue.