The cockpit voice recorder began recording the final thirty minutes of Flight93 at 09:31:57. At this moment, it recorded a hijacker’s voice, thought to be Jarrah, speaking with a halting command of accented English and breathing and panting heavily, apparently from exertion, perhaps from a struggle, "Ladies and gentlemen: here the captain. Please sit down, keep remaining seating. We have a bomb on board. So sit." The commission believed Jarrah tried to make an announcement to the passengers, but keyed the wrong switch, sending the message to Cleveland controllers; Mohamed Atta had made the same error on Flight 11. Werth understood the transmission, and tried to keep the hijacker pilot talking, responding, "Calling Cleveland center, you're unreadable. Say again, slowly." He sent a new text warning message to Flight 93: “High Security Alert. Secure Cockpit.” Werth asked other pilots in his sector to tail Flight 93, to keep eyes on the hijacked plane.