The story...

Bush didn't leave the school he was visiting in Florida until around 30 minutes after the second plane crash. Why didn't the security service evacuate him? Does this mean they knew he was in no danger?

Our take...

We're constantly told that no, 9/11 wouldn't have required a lot of people to pull off, compartmentalisation and the "need to know" would have limited those with inside knowledge. And yet claims such as this keep adding more people to the list. Because plainly, you couldn't simply have one or two security service personnel knowing he wouldn't be attacked: it would have to be all, to avoid confusion and people speaking out. And enough of the hierarchy for them not to be disciplined about it later.

If this were true, then the conspirators have now got another large group of people who, if any of them were to go public, could blow the whole story. Because it doesn't matter what else they know, simply saying that they knew Bush was safe would be a serious leak. And the gain to the conspirators of letting these people know is what, exactly? How does giving the security service advance knowledge of the attack, then letting them behave in what's claimed to be an unrealistic way, help the conspiracy at all?

Yes, that's okay, we know, people are just "asking questions". So let's suggest an answer. Where were the security service to take him? How did they know that the attackers might not be relying on Bush being moved? Perhaps there was a truck bomb waiting for Bush to be moved to the airport. Maybe there was an ambush planned there. What if Air Force One was the target? The Security Service staff at the school with Bush did not have an overview of what was going on, and as Bush was in an area that was secure on the ground, at least, then surely it's reasonable to take time to consider where Bush should go next. And take guidance from someone who was in the loop, back at the White House.

Those who suggest this wouldn't be reasonable at all point to Cheney as one possible example:

Meanwhile, Secret Service agents burst into Vice President Cheney’s White House office. They carried him under his arms—nearly lifting him off the ground—and propelled him down the steps into the White House basement and through a long tunnel toward an underground bunker. Accounts of when this happened vary greatly, from 9:06 [New York Times, 9/16/01 (B), Telegraph, 12/16/01] to after 9:30. [CBS, 9/11/02, Washington Post, 1/27/02] Cheney’s own account is vague and contradictory. [Meet the Press, 9/16/01] The one eyewitness account, by White House photographer David Bohrer, said it happened just after 9:00. [ABC, 9/14/02 (B)] It’s easy to see why the White House would have wanted this event placed at a later time (after Bush’s initial statement to the nation rather than after the second crash) to avoid the obvious question: if Cheney was immediately evacuated, why wasn’t Bush?
http://www.cooperativeresearch.org/essay.jsp?article=essayaninterestingday

However, this isn't a good comparison at all. Cheney was in the White House, and was moved to another part of, uh, the White House. There's no way this could expose him to risk, which isn't something you could say about moving Bush. 

Of course the problem with discussing this, is most of those involved have no real idea what they're talking about. I'm a Brit: even if you like what I do on this site, why should you trust my guesses about US security service procedure? And much the same applies for those on the other side of the argument. Unless they have an in-depth knowledge of situations like this, why should you take their opinions as fact?

So let's forget our opinions, then, and look at an account of how this was seen on that day. It's the one Richard Clarke gave us in his book Against All Enemies, and while brief, it's still interesting:

The television screen in the upper left was running CNN on mute. Noticing the President coming on, Lisa turned on the volume and the crisis conference halted to listen. "...into the World Trade Centre in an apparent attack on our country."

During the pause, I noticed that Brian Stafford, Director of the Secret Service, was now in the room. He pulled me aside. "We gotta get him out of there to somplace safe... and secret. I've stashed FLOTUS". FLOTUS was White House speak for Mrs Bush, First Lady of the United States, now in a heavily guarded, unmarked building in Washington...

"Can you work with Brian", I told [Franklin] Miller. "Figure out where to move the President? He can't come back here until we know what the shit is happening."..."

Page 6
Against All Enemies
Richard A Clarke

In itself this seems straightforward, but the important part is when it took place: Bush didn't deliver his remarks until 9:30. And yet, the Director of the Secret Service, at least as reported by Clarke, isn't astounded that Bush is still at the school. In fact it seems it's only just occurred to him that something needs to be done. It appears Stafford doesn't want to simply "get Bush out of the school", either -- he wants assistance in planning what their next move should be, from Clarke, who was the man in charge of the White House Situation Room at the time. Which surely was a reasonable idea.

Anyone intent on proving conspiracy could spice this up with guesses, assumptions and speculation, obviously. They might move on to say this simply proves Stafford wasn't doing his job properly, say. Or maybe Clarke lied about the whole thing to provide a cover. Of course a simpler explanation might be that the actions of Bush's security detail on 9/11 weren't so hard to understand after all, to those with real inside knowledge.