<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by jimpop:
This is based on the methods and tactics used at Khobar Towers and at the US African Embassy bombings.</font>
According to the FBI:
Khobar Towers Release
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">At about 10:00 p.m. on June 25, 1996, a tanker truck loaded with at least 5,000 pounds of plastic explosives was driven into the parking lot in front of the Khobar Towers residential complex in Dhahran. Moments later a massive explosion sheared the face off of Building 131, an eight-story structure which housed about 100 U.S. Air Force personnel. Although rooftop sentries were immediately suspicious of the truck -- parked some 80 feet from the building -- and attempted an evacuation, few escaped.</font>
In other words,
even though there were sentries watching, and
even though they started evacuating the building, the attack was successful. And this was evacuating military personnel, not random air travellers (the ones who will stop to get their carry ons before evacuating burning aircraft!).
I will also note, this was an attack where the drivers of the truck jumped out and got into a getaway car being driven by accomplices. al-Qaeda doesn't worry about getting out of their vehicles before the explosion.