Medium Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Situational Awareness
Deviation / Discrepancy - Procedural Security; Flight Deck / Cabin / Aircraft Event Passenger Misconduct
General Police / Security Involved
Human Factors
I (First Officer) was pilot monitoring on approach at about 700 feet AGL into LAX on 25L. I could hear through my headset and the flight deck door some sort of commotion that sounded like voices. I thought it was slightly unusual; but we were close to landing; [and] I wasn't sure if the flight attendants were simply doing their last minute duties before landing. On the landing rollout turn onto a high speed taxiway; we got a call from the flight attendants. My Captain and I recognized it and both agreed we were going to address it as soon as we completed our after landing duties since we were still slowing down and in a very high workload environment between the normal flows; checklist; and call to ops. Before we could complete our after landing flows; however; the flight attendants then called using the 'emergency' call button. The Captain immediately stopped the plane and informed ATC while I talked to the flight attendants. The flight attendants told us we had a belligerent passenger; who had taken her seat belt off during approach and was walking around the cabin. I relayed this information to the Captain. We tried to ascertain what the current status of the passenger was to determine if she was still a threat. The flight attendants said she had returned to her seat with her seat belt fastened. Following the Captain's direction; I asked the flight attendant if they thought we needed a Law Enforcement Officer (LEO) to meet us at the gate; since the information we were getting appeared to indicate that the passenger had returned to her seat and fastened her seat belt and was complying. After a pause and the flight attendant's clear hesitation on making this decision; I suggested that we'd have a LEO meet us at the gate; which the flight attendants agreed was a good decision. I called ops; and worked through arranging a LEO to meet us at the gate. Unfortunately; in the chaos ops didn't know we were on the ground in LAX because our ACARS had failed midair on that leg. This resulted in some delay getting the ground crew to the gate to marshal us in and then waiting for the LEO to meet us at the gate after we had parked. We delayed deplaning the aircraft until the LEO could escort the passenger off the plane.I saw the passenger briefly in the jet bridge hitting the LEO while the LEO explained to her that she would be arrested [if] she didn't stop. I left to do my walk around; and when I returned; I saw her being carried away in handcuffs by two LEOs up the jet bridge.As the incident occurred we were informed that it was alcohol-related; and the passenger was clearly intoxicated. She had been served two alcoholic beverages during the flight; and according to the flight attendants; was perfectly normal after 1; but the second resulted in her belligerent behavior.Passengers being disruptive are a part of air travel; but there were a few lessons I learned to help make it smoother with less operational disruptions. First; explain to the flight attendants that they should let us know quickly if there's a potential problem. On final approach; one of us could conceivably have answered a call early on knowing there was simply an issue with a passenger. Then we could have called back when we had finished our initial after landing duties and better managed the workload.While the Captain and I performed great CRM during the whole event (clearly dividing who was doing what - Captain did taxiing and communicating with ATC while I talked with the flight attendants and coordinated with ops); things changed when our first form of communication with the flight attendants was after they had pushed the emergency call button. The Captain and I both feared when we saw that light go on that we might have been on fire or some other emergency requiring evacuation onto the taxiway. The Captain later informed the flight attendants that we were going to get to the situation as quickly as it was safe to do so; but the emergency callbutton might not have been necessary since at the time they called the passenger was in her seat with her seat belt fastened.Finally; I believe one of the important things for the flight attendants to learn is how much we pilots rely on them to paint a picture of what is happening in the cabin in a situation like this. Initially when they called up; it sounded like it was a minor issue that was under control and wouldn't require any special assistance; and it took a long time to come to the conclusion to pull the trigger on having security meet us at the gate. When we exited the flight deck at the gate; the Captain and I agreed that there was no doubt we needed security to meet us (and the Captain commented that if she'd been displaying that behavior when she boarded the flight; she would have still been in [departure airport] at the gate); as even though she was in her seat; she still was not complying with instructions and posing a threat to those around her (as evidenced by her repeatedly hitting the calm LEO while in the jet bridge). Having gotten this information better communicated to us would have allowed us to get to the gate quicker since we were stopped on the taxiway during the whole conversation with the flight attendants. While in this incident it did not make a difference; a different situation might result in a passenger being more physically aggressive; making a quick decision allow for a sooner end to the scenario with less damage or injury to passengers and crew. And while not as important; a quicker decision would have also mitigated some of the delay that this incident caused to the remaining flights of the day.
Air Carrier First Officer reported that an unruly passenger disrupted the cabin shortly before landing.