Question: When was Umar Farouk Abdulmutallab attempting to detonate plastic explosives on Northwest Airlines Flight 253?
Sentence (from "Northwest Airlines Flight 253"): Had the attempt succeeded, it would have surpassed American Airlines Flight 191 as the deadliest aviation occurrence on U.S. soil and tied Iran Air Flight 655 as the eighth-deadliest of all time.
Relevant evidence: No