On January 13 a Boeing 737-800 operated by a Turkish low-cost airline called Pegasus Airlines left the side of the runway during its landing rollout in Trabzon, Turkey.
It then careered over a section of grass and down a steep slope. It stopped metres from the rocky water’s edge where it hung precariously. Passengers and crew escaped by clambering up the steeply sloping aisle and out of the rear doors into the relative safety of the muddy cliff.
Here a serving UK airline captain – who has flown both Airbus and Boeing airliners – explains how to him the accident looks very similar to one in Brazil, where the pilots became seemingly confused about one of the engines remaining in high thrust on landing. It was a tragedy in which 199 people lost their lives.
On January 13 a Boeing 737-800 operated by a Turkish low-cost airline called Pegasus Airlines left the side of the runway during its landing rollout, pictured
The pilot, speaking anonymously, said: ‘How could anything go so wrong as to cause such a calamity when the landing is almost over? How close was it to catastrophe? The truth is that nobody yet knows the cause. Commercial aircraft accidents take months or years to investigate, such is the painstaking nature of that work.
‘What is certain is that a catastrophe was narrowly avoided. A few metres further, a little more speed, a fire breaking out. Any of these events could have caused lives to be lost.
‘It has been reported that the right-hand engine may have suddenly increased thrust and caused the aircraft to swing violently to the left. It is possible that something like this occurred late into the landing.
‘As the aircraft slows the air flowing over the fin and rudder (often referred to as the tail) reduces and control is weakened to a point where the aircraft relies on the grip of its tyres on the runway to keep straight.
‘A very large amount of thrust at a very slow speed would rapidly overcome the grip of the small nose tyre and turn the aircraft.’
The pilot draws a comparison between the Pegasus accident and a 2007 disaster in Brazil, where an Airbus careered off the runway on landing and burst into flames in a warehouse, killing all 187 on board and 12 on the ground.
He continued: ‘We know from a tragic accident in São Paulo, Brazil, in July 2007 that such an event can be exceptionally confusing for the flight crew. In such a case the pace of events can change very quickly.
‘The two accidents bear some similarities.
‘A TAM Airbus A320 was being flown with one of its two thrust reversers inoperative. This called for the pilots, both of whom had been flying for more than 30 years, to select only one reverse thruster and idle the other – the thrust levers and reverse thrust are all on the same lever – just after touchdown.
‘However, the pilots made a critical error in only moving one thrust lever from the high thrust position. The result was increasing thrust on the opposite engine as a system known as autothrust switched off.
A TAM Airbus A320 crashed in 2007, with the deaths of 199 people, after it careered down the runway with one engine in reverse and the other with thrust engaged
‘The aircraft sped off the side of the runway and down a steep embankment into a warehouse. All 187 on board were killed as were 12 people on the ground.
‘The investigation painted a picture of confusion at the moment of touchdown as a normal landing suddenly went awry. Unaware of their error, the combination of events at the point of landing rapidly overcame the pilots’ ability to resolve what they were seeing. Solutions were possible but the pilots missed the opportunity to use them.
‘One theory about the cause of the accident is that the pilots didn’t realise that the autothrust system had been disengaged by the thrust lever being reduced to idle. They would have expected this to reduce thrust on both engines, just like on all of their previous landings.
‘Officials said that the chances of the right engine increasing thrust through a mechanical fault were extremely unlikely.’
The pilot added that despite on-board technology being extremely sophisticated, it’s the pilots’ skill and training that is still the most important factor for safe airline operations.
He said: ‘Today airliners like the 737 are highly automated and remarkably reliable. But the skill and judgement of the flight crew is still the key to the safe operation of these impressive machines.
‘Highly realistic simulators are used to expose flight crews to a variety of failures. Rigorous training reviews pilots’ competency and decision-making to hone their performance.
‘Seemingly split-second instinctive decisions are the result of years of training and experience.
‘Just like in São Paulo the investigation into the Trabzon accident will reveal a chain of events leading up to the accident. Recommendations will be made and lessons learned. In an industry that trades on safety standing still is not an option.’