Cleveland flight controller Stacey Taylor has been warned to watch transcontinental flights heading west for anything suspicious. She later recalls, “I hear one of the controllers behind me go, ‘Oh, my God, oh my God,’ and he starts yelling for the supervisor. He goes, ‘What is this plane doing? What is this plane doing?’ I wasn’t that busy at the time, and I pulled it up on my screen and he was climbing and descending and climbing and descending, but very gradually. He’d go up 300 feet, he’d go down 300 feet. And it turned out to be United 93.” (Note the time of this incident is not specified, but presumably it is prior to when Cleveland controllers note Flight 93 descends 700 feet at 9:29 a.m. [MSNBC, 9/11/2002]