Northwest Airlines Flight 253

The attempted bombing of Northwest Airlines Flight 253 occurred on December 25, 2009, aboard an Airbus A330 as it prepared to land at Detroit Metropolitan Airport following a transatlantic flight from Amsterdam. Attributed to the terrorist organization al-Qaeda in the Arabian Peninsula (AQAP), the act was undertaken by 23-year-old Nigerian national Umar Farouk Abdulmutallab using chemical explosives sewn to his underwear. These circumstances, including the date, led to Abdulmutallab being commonly nicknamed either the "Underwear bomber" or "Christmas Day bomber" by American media outlets.

The event was the second airliner bombing attempt in the United States in eight years, following the 2001 American Airlines Flight 63 bombing attempt. If successful, the attack would have surpassed American Airlines Flight 191 as the deadliest airplane crash on U.S. soil and tied Iran Air Flight 655 as the eighth-deadliest of all time. It was also the second event in 2009 involving an Airbus A330 (after the June 1 crash of Air France Flight 447), and the final operational occurrence for Northwest Airlines (preceding that airline's merger with Delta Air Lines) the following month.

For his role in the plot, Abdulmutallab was convicted as a civilian criminal in US federal court and sentenced to life imprisonment without parole. AQAP leader Anwar al-Awlaki, who reportedly inspired Abdulmutallab and "masterminded" the attack, was killed two years later as the target of a drone strike in Yemen.