The point was that New York City saw a large plane hit one of its largest buildings. The failure mode was known. It just happened to be that no one cared to design for that failure mode later.
The last plane crash into a building in NY before 2001 was back in 1946, when a transport aircraft from the US Army Air Forces flew into 40 Wall Street.
That was 55 years before 9/11, and 20 years before construction of the twin towers was started, it was believed to be a solved problem, which in context wasn’t that unreasonable.
The point was that New York City saw a large plane hit one of its largest buildings. The failure mode was known. It just happened to be that no one cared to design for that failure mode later.
The last plane crash into a building in NY before 2001 was back in 1946, when a transport aircraft from the US Army Air Forces flew into 40 Wall Street.
That was 55 years before 9/11, and 20 years before construction of the twin towers was started, it was believed to be a solved problem, which in context wasn’t that unreasonable.