United Airlines held an exercise 12 days before 9/11 based on the scenario of an airliner crashing and it was so realistic that some employees were devastated because they thought a plane really had crashed.

Submission statement: Andy Studdert, chief operating officer of United Airlines at the time of the 9/11 attacks, recalls that early in 2001, he had been concerned because United Airlines had not had a “real accident” in over 15 years and so its personnel weren’t prepared to deal with an emergency if one should happen. He therefore decided to arrange a “no-notice drill.”

The exercise took place on August 30, 2001. Studdert arranged to have the pilot of a Boeing 747 that was on its way to Australia call in, say his plane had suffered an engine failure and was descending rapidly, and then stop talking mid-word, thereby giving the impression that the plane had crashed.

Unfortunately, airline employees didn’t realize the incident was part of an exercise and thought a plane really had crashed. Some of them were therefore devastated. “There are people throwing up in the hall, there are people crying, there are people just staring out the windows,” Studdert recalls. And yet, despite this, he allowed the exercise to continue for half an hour before he announced, “This has been a no-notice drill, there is no event, everything’s fine.”

The exercise occurred just 12 days before 9/11–a day when two United Airlines planes crashed for real.