Investigators get voice recorder from JetBlue flight By Josh Levs, CNN March 29, 2012 -- Updated 1727 GMT (0127 HKT) Federal regulations: Recorders must tape conversations on planes made since 1991 Federal complaint alleges captain made remarks that worried first officer The co-pilot's mother says he would not consider himself a hero The incident took place on the 10th anniversary of his sister's death, his mother says (CNN) -- The FBI has obtained the cockpit voice recorder from JetBlue Flight 191, which had to make an emergency landing this week, a law enforcement official told CNN on Thursday. The FBI had no comment. Investigators are probing the apparent midair meltdown of the captain, Clayton Osbon, whose remarks and erratic behavior led the co-pilot to lock him out of the cockpit. Crew and passengers subdued Osbon as he screamed and banged on the door so hard that the first officer thought Osbon would come through, according to a federal criminal complaint filed Wednesday against Osbon. The complaint says Osbon began making remarks during the flight that concerned the first officer, who is his co-pilot. Osbon yelled over the radio to air traffic control and instructed them to be quiet. Osbon turned off the radios in the aircraft, dimmed his monitors and sternly admonished the FO (first officer) for trying to talk on the radio," the U.S. Attorney's Office in the Northern District of Texas said in a statement. When Osbon said 'we need to take a leap of faith,' the FO stated that he became very worried. Osbon told the FO that 'we're not going to Vegas,' and began giving what the FO described as a sermon. It was not immediately known whether the alleged remarks are audible on the recorder. But federal regulations state that planes manufactured since 1991 must record cockpit chatter on microphones. The JetBlue plane was new and would be subject to the rule. JetBlue has repeatedly praised the first officer, along with the off-duty captain who stepped in to assist and other crew members Tuesday. Some passengers have referred to the first officer as a hero. But his mother told CNN on Thursday that he would reject the label. Knowing my son, he would think that he's not a hero. He just did what he was paid to do," Jean Beatrice Dowd said of her son Jason Dowd. That's just his job, and he loves his job. He's just a quiet man. He called his parents the night of the incident, his mother said. He was pretty shaken up, and he couldn't say much. The incident took place on a significant date for the family -- the 10th anniversary of the death of Jason Dowd's older sister, who died of cancer, Jean Dowd said. "I know he was thinking of her too at the time this was all going on," Dowd said. The incident "has been earthshaking for us, too," she said. To lose him would have been terrible for us. Jason Dowd, 41, who is married and has two young children, has not made a public statement. He is in New York, speaking with officials about the incident, his mother said. The flight took off from New York and was heading to Las Vegas when it made the emergency landing in Amarillo, Texas. CNN's Aaron Cooper and Carol Cratty contributed to this report.