The city prosecutor is taking the rare step of filing criminal charges against a carrier that operates at Long Beach Airport, alleging it violated the city’s noise ordinance 16 times in the last 12 months.

City Prosecutor Doug Haubert, in a courtesy email sent late Thursday to members of the City Council, said Mesa Airlines, doing business as American Eagle—an affiliate of American Airlines—has repeatedly violated the city’s strict regulations on aircraft noise, even after intervention from the city.

“Before filing this case in court, Airport staff was in communication with American Eagle to inform them of Long Beach’s ordinance and to encourage their compliance,” Haubert said in the email.

Staff at Long Beach Airport reported nine of American Eagle’s flights were in violation of the city’s ordinance in 2017, and in the first half of 2018, the airline had six flights in violation.

“Although Airport staff continued to work with American Eagle in an effort to reduce the violations, there was not a consistent effort by American Eagle and violations continued,” Haubert wrote.

Between Aug. 14, 2018, and Aug. 2 of this year, the airline violated the policy 16 times, Haubert said in the note.

American Eagle averages three daily flights to and from Long Beach and Phoenix, Arizona, which is its hub.

Curtis Blessing, a spokesman for American Airlines, said in an email Friday that the company is researching the legal action and would review it in coordination with Mesa Airlines.

Long Beach’s noise ordinance forbids commercial plane operations between 10 p.m. and 7 a.m., among other restrictions. Airlines are first issued a warning and small fine, and then they are fined progressively steeper penalties if violations continue.

As a last resort, the ordinance allows criminal prosecution after failure to adhere to local law, though it is rare for the city to take this step.

Haubert said in the email that the Prosecutor’s Office has filed just four previous criminal cases against airlines since 2002. The last one was in 2015 against operator Kalitta Charters, LLC.

In the most recent case, Kalitta agreed to pay the city $54,000 in fines as part of a plea agreement. The city had filed 13 misdemeanor charges against the Michigan-based airline for operations between June 2014 and March 2015.

Other cases have been filed against Komar Aviation, JetBlue Airways and American Airlines, most of them resulting in consent agreements.

Several airlines have in recent years violated the city’s noise ordinance, most notably JetBlue, the largest carrier at the local airport. The airline in May lost an appeal in challenging $96,000 in fines it accrued for late flights in 2017.

Haubert declined to discuss the specifics of the case against American Eagle because it is early in the process. However he said generally, a criminal case is only filed when it becomes apparent that an operator is not going to take reasonable steps to avoid late night flights.

“The goal in a case like this is to get compliance with the law,” he wrote, “and if filing a criminal complaint is the only way to accomplish this I will not hesitate to take that step.

“People who live in Long Beach invested in their homes with the assumption that airlines will follow the law and operators who use the airport know that criminal prosecution will result when violations continue.”

The city sent American Eagle a court summons on Wednesday, with an arraignment scheduled for early October. In criminal cases against corporations, typically no one is arrested.