Not the one in Shanksville. The one over the White House, witnessed by CNN’s John King, among others.

It was about 10 am on 9-11. The hijacked planes had already hit the World Trade Center and the Pentagon (the Pentagon crash occurring at 9:37 am), and the White House was among the government buildings in Washington that were being evacuated. NORAD had scrambled fighters into the air without any clear idea of where the fighters would go or what their responsibilities or orders were. At that moment, a mysterious plane appeared in the restricted air space above the White House. That plane, as you’ll see in the clip, was most likely an Air Force E-4B flying command post.

The CNN story gives too much air time to the Truthers for my tastes, but it’s not hard to see why. In the absence of having every single thing about that day explained, conspiracy theories arise among the paranoid and narcissistic. And the government has no long-term interest in acknowledging that the E-4B was sent up, why it was sent up or who might have been on board. In telling our citizens every single thing about what the E-4B might have been used to do on 9-11, we would also be telling our enemies quite a bit more about that plane’s roles and capabilities than would be prudent.

If you sift through the 9-11 Commission report, it’s not all that difficult to come up with some roles the E-4B might have played without resorting to Trutherism.

9-11 was probably the single most chaotic day in US history. We had an unknown number of planes hijacked by an unknown number of terrorists from an as of that time unknown group, and until the planes began to crash into buildings, the hijackers’ intentions were unknown. The hijackers turned off or manipulated the transponders in the planes they had seized, crippling the FAA’s ability to track them and also making it more difficult for military planes to find them for potential escort or shoot-downs. In the early minutes of 9-11, it wasn’t clear what the nation was facing or what the emergency’s full scope was.

I’m former Air Force, and even I don’t know a lot about the E-4B. It’s a highly classified “doomsday plane” built to make sure that the government survives an extreme emergency. 9-11 was an extreme emergency. Why wouldn’t a standing order to send that plane up in the event of an extreme emergency be enacted when such an emergency arose? It would be stranger if the E-4B had never launched on 9-11, than the fact that it did launch but the government hasn’t seen fit to explain its role.

Now, what might it have been doing? Well, we all know that President Bush was in Florida that morning, reading books to school kids and touting his education policies. From Florida, he flew a zigzag route around the country in Air Force One before returning to Washington that evening. At the moment that the mystery plane is spotted over Washington, United 93 was still airborne, the last of the known hijacked planes to remain aloft, but there were other planes still flying on to their destinations or to the nearest available airport. Flights had been grounded, but grounding flights that are already underway takes time, as the air crews have to find places to land and coordinate their flights and landings with airports and with other planes, landings which were unplanned and being conducted on a very ad hoc basis. With its transponder off, ground controllers had little way of tracking U93. It was thought to be en route to Washington with unknown but by then presumably ill intentions. The government had every reason to suspect that there were other planes in the sky that were either already hijacked or would soon be hijacked. But there was massive confusion within the national command authority–were the scrambled fighters authorized to shoot down planes or not? The E-4B might have been sent up to use its radar to determine where U93 was and if there were other planes in the skies that needed to be checked out. Since fighters had been scrambled from Langley AFB in Va and Andrews AFB in Md, the E-4B might have been acting as an AWACS and coordinating their movements. It might also have been carrying high ranking military officers or cabinet officials as part of its doomsday role. At that point, we didn’t know if the hijackings were the core enemy strategy, or merely a precursor to more extensive attacks. The E-4B might have been aloft just in case the latter turned out to be the case, to get someone in line for the presidency out of harm’s way.

That’s speculation of course, but it makes more sense than to just assert that the E-4B was command on control for the hijacked 9-11 aircraft, which had mostly already crashed into buildings that would be brought down in controlled demolitions or hit by…missile? That’s where the Truthers come down on the mystery plane, to a theory that has thousands of moving parts, makes no sense and is harder to believe than anything the 9-11 Commission reported.

The fact at the end of the day is that you’ll never explain every single thing about 9-11. Some questions will always remain unanswered, either because those who have the answers are dead, or because those who have the answers have legitimate national security reasons to remain silent, or because life is full of anomalies that require no nefarious reason for their existence. To require that every single thing about 9-11 be wrapped up tight with ribbons and bows is to require the impossible. Real life doesn’t work that way. For the Truthers, anomalies or the few unexplained aspects of 9-11 are room for irresponsible conjecture and accusations. For the rest of us, the adults in the room, it’s hardly remarkable that there are things about that day that remain unexplained. Real life does work that way.