THIS EXPLAINS A FEW THINGS "How a 50-year-old design came back to haunt Boeing with its troubled 737 Max jet "

"Boeing has to sit down and ask itself how long they can keep updating this airplane," said Douglas Moss, an instructor at USC's Viterbi Aviation Safety and Security Program, a former United Airlines captain, an attorney and a former Air Force test pilot. "We are getting to the point where legacy features are such a drag on the airplane that we have to go to a clean-sheet airplane."

https://www.latimes.com/local/california/la-fi-boeing-max-design-20190315-story.html#nt=latestnews