Reports of unruly passengers rose five times in 2021 compared to the year before. There are still about twice as many incidents as pre-pandemic. International aviation rules classify disruptive passengers into four levels. Since the pandemic, incidents with unruly passengers on airlines have escalated. There were almost 6,000 reports in 2021, nearly five-times as many as a year earlier, according to data from the Federal Aviation Administration. Over the next three years, the number of incidents remained roughly twice the amount reported pre-pandemic. Up to September 28, there have been 1,205 reports this year. That's already more than in 2020, although it's an encouraging sign that the numbers are falling. "Incidents where airline passengers have disrupted flights with threatening or violent behavior are an ongoing problem and airlines have seen rapid growth in occurrences since 2021," the FAA says on its page for such statistics. "The rate of unruly passenger incidents steadily dropped by over 80% since record highs in early 2021, but recent increases show there remains more work to do," it adds. The International Civil Aviation Organization defines a disruptive passenger as one "who fails to respect the rules of conduct at an airport or on board an aircraft or to follow the instructions of the airport staff or crew members and thereby disturbs the good order and discipline at an airport or on board the aircraft."