One of the many, many problems 9/11 “truthers” have besides hilarious infighting over money and a lack of critical thinking skills is in what happened to the passengers of United Airlines Flight 93. According to the “official story” (aka reality), some passengers overpowered the highjackers and forced the plane to crash in Shanksville, PA rather than allow themselves to be used in a suicide attack on either the White House or the US Capitol building. But since the conspiracy theorists insist that there either were no planes at all or that they were controlled by remote or something to that effect, they need to fit the fourth hijacked plane and its passengers into their conspiracy theory by some other means.
Usually most of these people have at least the presence of mind to not get into speculation about this issue because it leaves them open to the kind of ridicule they deserve. Sometimes even crazy people have some form of quality control. Even some creationists do, too. But like any fringe group, there are always some people who have no filter to strain out the really obviously deranged from the mere mildly disturbing.
For example you have this guy. According to him, the plane’s captain was put on a fake plane which was then followed by two other planes. This worked really well for the conspiracy because you always want to make sure you have as many people involved as possible. This especially so when it’s only to kill one guy (the pilot) after he’s said the necessary lines for the Voice Splicing Modules (it’s apparently illegal to mention these magical devices without bold print).
So if things are too normal for you, try reading this guy’s crackpot theories. Maybe stock up on asprin or alcohol first, though.