Ed Yourdon does not know what he is talking about. His examples of Y2K disasters proceed entirely from made-up scenarios of doom and not from any understanding of the underlying processes and code. His examples are ludicrous; absolutely laughable.
The basic premise, that Y2K bugs will cause widespread crashes, is silly enough (try setting the clock on your computer past 2000 and running all your programs; nothing odd happens), but the idea that any computer's crashing will cause the downfall of civilization is outlandish. Computers crash all the time -- there are already processes and infrastructure to deal with it. A whole lot of computers crashing at once could conceivably make things annoying for a while, but more in the nature of slowed-down than stopped.
Here's an example: can the airlines run without computers? Yes. They have complete procedures in place to issue tickets, take tickets, move baggage, etc. without any computers involved. They did it in the 50's;! they can still do it today. It's just slower and more prone to error. Some Airbus planes are dependent on their computers for certain operations, but even they have manual fallbacks. They're not going to fall out of the sky, and they're not going to crash in 2000; it's unlikely that airplane computers pay attention to the date at all.
I cannot stress enough: DO NOT BUY THIS BOOK. Don't put another dollar into the hands of someone who is uninformed and milking the hype machine for all it's worth. Check it out from the library if you must.