Air Force One is the designation given to any aircraft transporting the President of the United States of America. "Air Force One" is typically used to refer to the two highly modified 747s that normally transport the president (tail numbers 28000 and 29000).
Assassination of Thomas Richards
President Matthew Ellis was aboard Air Force One when he witnessed another of the Mandarin's broadcasts, where he was pointing a gun at Thomas Richards, an accountant for the Roxxon Oil Corporation. The Mandarin demanded President Ellis to call him; otherwise, he would shoot Richards in the head.
Despite his advisors recommended him not do it, Ellis called the Mandarin, who did not answer the phone and went on to shoot Richards. The Mandarin warned Ellis that there was nothing he could do to save himself from the next attack.
Kidnapping of President Ellis
While Air Force One was flying over Florida, Savin killed some of the agents escorting President Ellis and revealed his true face under the armor. Ellis prompted Savin to kill him, but Savin simply told him that was not the way the Mandarin worked.
Savin put Ellis inside the armor, programmed it to fly back to the Norco freighter and remained aboard the plane. The Iron Man Armor, remotely controlled by Tony Stark, ambushed Savin and was able to subdue him. Stark interrogated Savin about the whereabouts of President Ellis and Savin detonated an explosive that opened a hole in the plane, sucking out many of the crew. Before jumping to rescue the crew, Stark was able to kill Savin, firing a shot from the repulsor in his chest at point blank range.