Southwest Airlines is delaying serving alcohol again on flights after an increase in incidents of unruly passengers. The airline was planning to resume selling alcohol next month on Hawaii flights and in July on other flights, a move that was questioned by the president of the union representing Southwest flight attendants.

“Given the recent uptick in industry-wide incidents of passenger disruptions inflight, we have made the decision to pause the previously announced re-start of alcohol service,” said Southwest spokesman Chris Mainz.

Mainz said the decision might disappoint some customers, “but we feel this is the right decision at this time in the interest of the safety and comfort of all customers and crew onboard.”

The airline has not determined new dates for selling alcohol, Mainz said.

The president of the flight attendants’ union, Lyn Montgomery, said that there were 477 incidents of “misconduct” by passengers on Southwest planes between April 8 and May 15, and that her members were concerned about Southwest’s plan to resume selling alcohol on flights.

Montgomery raised the issue after a flight attendant was punched in the face by a passenger recently after a flight in California. A 28-year-old woman faces a felony charge of battery, although a police report did not mention alcohol.

The US Federal Aviation Administration has similarly reported a surge in incidents aboard planes, reporting last week that since Jan. 1 it has received approximately 2,500 reports of unruly behavior by passengers, including about 1,900 reports of passengers refusing to comply with the federal facemask mandate.