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Adam Podhorski: "Pilots didn't know there was a system to compensate for loss of strength."
Professor Adam Podhorski of Tecnun explains the importance of software in air accident prevention
We reproduce below the interview with Tecnun professor Adam Podhoroski, published today in the Diario Vasco . Podhorski explains the importance of software in the prevention of air accidents:
157 people died last Sunday when the Ethiopian Airlines flight operated by a Boeing 737 MAX 8, bound for Nairobi, crashed shortly after takeoff. On October 29, 2018, another 189 people died when a Lion Air flight covered by another Boeing 737 MAX 8 went down in the Java Sea. According to the first hypotheses, sensors that stabilize the nose of the aircraft during takeoff may have failed using a computer safety system called MCAS of these aircraft, which have had their operation suspended in Europe since Tuesday. Adam Podhorski holds a PhD in Engineering and is a professor of signal processing and embedded systems at Tecnun. He is currently working on the project CODISAVA (Distributed Control Advanced for Safety and Energy Efficiency in Air Transport) with "the goal to develop fundamental technologies for the future electric aircraft," he explains.
Regarding the accidents involving the Boeing 737 MAX 8, this Polish engineer confirms that these airplanes have a "tendency to lift the nose, which can cause the airplane to stall, lose lift and fall". In view of this status Podhorski explains that a "compensation system that the pilots did not even know existed" is necessary on this Boeing model .
- What's going on with this new Boeing model ?
- Larger and more powerful engines have been mounted on these aircraft than on previous versions with the goal to achieve greater energy savings, which could be as much as 14% at best, which is a lot. But because those engines are larger they don't fit under the wing and have had to be moved to the front of the aircraft. They have also had to make the front landing gear higher so that those engines have room. These changes already make the aircraft behave differently in flight.
- So what's the problem?
- This aircraft has a natural tendency to raise its nose. When the nose rises too high, the aircraft loses the power that keeps it in the air, technically the aircraft enters the stall. To regain the stall, the nose has to be lowered so that the aircraft practically noses down and then horizontal flight is restored. For this manoeuvre, the aircraft must be at a sufficiently high altitude because it is going to fall a lot. If there is not enough height, there is no chance of recovery.
- Is there no way to rectify this loss?
- This requires a compensation system. It is a system operated by the onboard computer that controls the flight and that the pilots who operated this model did not even know it existed. They only found out about it last week. It is a computer safety system called MCAS and serves to compensate for the entrance stall. The planes have a detector called angle of attack, the angle between the plane and the runway. If the aircraft climbs too high, what this system does is that the flaps on the wings rise and compensate for this status so that the aircraft descends. But this way of acting was not even in the manuals of the airplane. Nor had the pilots seen it in training. Apparently, the pilots had already started to complain last week and to ask the company what other elements the plane had that they did not know about.
- What solutions can Boeing take?
- You have already sent directions on how to turn off this software system that may be behind the errors. It may be a solution that this model can fly without this system activated but I don't know how it may affect flight stability and behavior. That answer should be given by Boeing engineers. On the other hand, I think that this system is not very coordinated with the other systems installed on that model. It seems that the plane was alternately receiving contradictory orders.
- How is it possible that Boeing could not have foreseen what happened?
- It will be the commissions that investigate accidents and clarify the facts that will determine the causes of the accident and offer recommendations so that they do not happen again in the future. But it seems to me, knowing what we know today, that they have not tested this model sufficiently because this failure should have been discovered earlier. It is not a fact that happens with extreme flight or runway conditions, it seems to have happened in both accidents on a normal flying status .