When Boeing re-designed the 737 Max 8 to be more fuel efficient, it moved the larger engines forward which made the plane prone to having its nose point skyward which creates a danger of stalling. So the MCAS system automatically pointed the nose downward without pilot input.
The problem was that Boeing never really told the pilots of these new airplanes that the MCAS system even existed or what it does. They just quietly rolled it out thinking there would be no problems with a computer program that could automatically nosedive the airplane.
Donald Trump and USA have down played this safety issue in the interest of profits. By telling the world just use them they are safe. This is the second accident in just 6 months.
UK and Europe have banned this model of flight. Next time when you fly ask if it’s a Boeing 737 Max 8.