Barbara Arestegui

At least four of the nine flight attendants who will be on American Airlines Flight 11—the first plane to hit the World Trade Center—on 9/11 are not originally scheduled to be on this flight, but are assigned to it shortly before September 11 or early in the morning of 9/11:
Jeffrey Collman does not “normally work the Boston-to-Los Angeles route but [makes] an exception to get vacation time at the end of the month.” [Seattle Times, 9/17/2001]
Barbara “Bobbi” Arestegui accepts extra shifts as she is saving up her earned vacation time. [Cape Cod Times, 9/18/2001; Cape Cod Times, 9/10/2002; Cape Cod Times, 9/11/2006]
Jean Roger is on a “standby” work list in September 2001. Someone calls in sick the morning of 9/11 and she takes their place. [Chicago Tribune, 9/15/2001; Boston Globe, 9/9/2003]
Sara Low is “not originally scheduled to work” Flight 11. [Associated Press, 9/25/2001]
John Ogonowski, the plane’s pilot, is also not originally scheduled to be on Flight 11, but requests to fly it shortly before September 11 (see Shortly Before September 11, 2001). [Georgetown Record, 9/18/2003] Many of the flight attendants on the other three hijacked planes are also only assigned to those flights shortly before 9/11 (see Shortly Before September 11, 2001, Shortly Before September 11, 2001-Early Morning September 11, 2001, and Shortly Before September 11, 2001).