Authorities are investigating two unruly-passenger cases that prompted two separate Hawaiian Airlines flights to return Thursday to Daniel K. Inouye International Airport.

One incident involved an alleged unprovoked attack against a flight attendant on an interisland flight bound for Hilo, while the other involved a passenger who allegedly defied the federal face mask mandate on a flight to Seattle.

In the first case, state sheriff’s deputies arrested a 32-year-old passenger after he allegedly punched a flight attendant twice in an unprovoked attack.

Flight HA 152 departed from the Honolulu airport at 7:30 a.m. bound for Hilo. Soon after, “a passenger assaulted one of our flight attendants, who was walking the aisle, in an unprovoked incident,” said spokesman Alex Da Silva.

Bill Paris, who was a passenger on the flight, said the assault occurred near the front of the cabin. Both the passenger and the flight attendant were described as male.

Taylor Garland, spokeswoman of the Association of Flight Attendants-CWA, said the passenger punched the attendant in the chest and back of the head while the attendant was walking through the cabin to collect trash. “This behavior on board is unacceptable,” Garland said. “We are providing support to the flight attendant involved in the incident.”

Preliminary information indicates the assault was not triggered by noncompliance with the mask mandate.

The flight diverted back to Honolulu where deputy sheriffs escorted the unruly passenger off the plane and arrested him on suspicion of third-degree assault, according to Toni Schwartz, spokeswoman of the state Department of Public Safety.

The flight attendant was “shaken up” but doing well, said Hawaiian Airlines President and Chief Executive Officer Peter Ingram in a memo sent to all employees.

The case has been turned over to federal authorities.

In his memo, Ingram said Hawaiian Airlines has a zero-tolerance policy for disruptive and dangerous behavior in its cabins and has banned or denied boarding to 98 passengers so far this year. “I join President Biden in his call to stop bad behavior aboard flights and toward flight attendants in particular, who have borne the brunt of this nonsense. Our flight attendants consistently deliver warmth and care while ensuring the safety of all who fly with us, which has been an especially tall order during this pandemic.”

Several hours later, authorities responded to a second unruly-passenger incident on a separate Hawaiian Airlines flight bound for Seattle.

At 1:05 p.m., Flight HA 22 departed Daniel K. Inouye International Airport. Approximately two hours later the captain was notified of a passenger who refused to comply with the mask mandate and “caused a disturbance to other guests,” said Hawaiian Airlines spokeswoman Tara Shimooka. “Our flight attendants, along with an off-duty pilot, were able to de-escalate the situation.”

Out of an abundance of caution, the captain decided to return to Honolulu, where local authorities met the aircraft upon arrival shortly after 5:50 p.m.

There were no injuries reported.

The disturbance aboard the flight involved an adult female passenger, said spokesman Jai Cunningham of the state Department of Transportation. The passenger’s age was not immediately available.

In January the Federal Aviation Administration adopted a stricter enforcement policy in response to an increase in unruly-passenger incidents. Under the policy, the FAA moves directly to issuing hefty fines.

As of Tuesday the agency had received reports of more than 4,300 unruly passengers this year.

The FAA also reported that the rate of unruly-passenger incidents on commercial flights has dropped significantly since the launch of the zero-tolerance policy awareness campaign, but the rate remains high.

As of last week the federal agency reported that incidents were occurring approximately 6 times per 10,000 flights, a 50% drop from early 2021, “but the rate remains more than twice as high as the end of 2020,” the FAA said Thursday.

In a statement on the agency’s website, FAA Administrator Steve Dickson said, “Our work is having an impact and the trend is moving in the right direction. But we need the progress to continue. This remains a serious safety threat, and one incident is one too many.”

Thursday’s incidents on the two Hawaiian Airlines flights occurred on the same day the House Subcommittee on Aviation held a hearing on “air rage” involving disruptive travelers and impacts to workers and airlines.

Sara Nelson, international president of the Association of Flight Attendants-CWA, AFL-CIO which represents flight attendants at 17 airlines across the country, testified about the verbal and physical abuse flight attendants face from unruly travelers.

“The safety of every passenger and crew member on board is in jeopardy when our duties are interrupted or needless distractions arise,” Nelson said.