Sole Survivor by Dean Koontz

Joe Carpenter's wife and two children perished with more than three hundred others in the crash of United Airlines Flight 353. But one year later, haunted by the loss of his family and desperate to find purpose in life, he discovers that the official story of Flight 353 is a treacherous lie.
They say it was an accident. It was not. They say there were no survivors: that the crash was too devastating for anyone to live through it. But incredibly, Joe discovers one woman walked away unhurt from the disaster, with a secret that will change the world...