Today, 53 years ago, on August 29, 1972 (Lunar Calendar, July 21, 1972), the two airlines carried out check-in packages before boarding. On August 29, 1972, World Airlines and American Airlines began checking their packages before boarding passengers. Officials of the two airlines said that this step not only prevented the hijacking, but also encouraged some travelers to return by plane. The check-in process increased the normal travel time by 30 minutes. Passengers must be alert during check-in to the gifts of strangers, especially the gifts accepted before boarding. On August 26, two British women received a souvenir sent by an Arab acquaintance before boarding. On the plane, when this gift exploded, they were all wounded.