Air rage is on the decline in the United States after new fines were put in place January, but the number of incidents is still twice as high as last year, according to Federal Aviation Administration data released on Thursday.

As of last week, reported occurrences involving unruly airline passengers were six per 10,000 flights.

That's a 50 percent drop from early this year. FAA Administrator Steve Dickson, in a statement, said even one incident is one too many and called air rage a "serious safety threat."

Numbers remain high compared to a year ago as some fliers balked at a federal face-mask mandate on airplanes. Hundreds of passengers have been banned from some airlines and some have faced $9,000 in federal civil fines for defying mask requirements.

Airline staff have been on the receiving end of much of the rage, leading some airlines to cancel sales of alcoholic beverages on flights.

Airline unions have called on Attorney General Merrick Garland and the Department of Justice to prosecute disruptive and violent air passengers.

Senior Democratic lawmakers on Monday also requested the same from the Attorney General.