Federal prosecutors in Salt Lake City have decided not to file any charges in the death of a 19-year-old man who was beaten by fellow passengers last month after he broke into the cockpit of a Southwest Airlines flight to Salt Lake City from Las Vegas.

As many as eight of the 120 passengers on the Boeing 737 subdued the man, Jonathan Burton of Las Vegas, who was removed from the jet after it landed and taken to a Salt Lake City hospital, where he was pronounced dead. Federal investigators and prosecutors declined to provide details of the incident or the inquiry that followed, including the names of the other passengers involved in the incident.

But the United States attorney for Utah, Paul M. Warner, who concluded last week that the death was a homicide, said the passengers who subdued Mr. Burton acted out of self-defense and did not demonstrate ''criminal intent,'' at least not to the extent that prosecutors believed they could win a conviction in court.

Ed Stewart, a spokesman for the airline, said today that it was ''crystal clear'' that Mr. Burton was trying to disrupt the flight, calling his actions ''less an example of air rage than an attempted hijacking.''