DALLAS (AP) — 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,” Southwest spokesman Chris Mainz said Friday.

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 this week 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 last Sunday after a flight in California. A 28-year-old woman faces a felony charge of battery, although a police report did not mention alcohol.