American Airlines Flight 444 was a scheduled American Airlines flight from Chicago to Washington, D.C.'s National Airport. On November 15, 1979, the Boeing 727 serving the flight was attacked by Ted Kaczynski (also known as the Unabomber), who sent a pipe bomb in the mail and set it to detonate at a certain altitude. The bomb partially detonated in the cargo hold and caused "a sucking explosion and a loss of pressure," which was then followed by large quantities of smoke filling the passenger cabin, forcing the pilots to make an emergency landing at Dulles International Airport. Twelve passengers had to be treated afterward for smoke inhalation.

Bombing a commercial airliner, especially one flying through an interstate route as Flight 444 was at the time, and still is, a federal criminal offense. After the incident, the FBI was quickly called in to investigate. The FBI investigators assigned to the case found similarities between the still relatively intact pipe bomb and two bombs that had previously detonated at Northwestern University. This prompted federal authorities to assign the name "Unabomber" (for University and Airline Bomber) to the then-unknown suspect, and sparked one of the longest and most expensive manhunts in FBI history, which finally ended 17 years later with Ted Kaczynski being arrested and charged in 1996.