Date: 201711
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Dusk
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise; Descent
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Flight Deck / Cabin / Aircraft Event Passenger Misconduct
Detector: Person Flight Attendant
When detected: In-flight
Result: General Police / Security Involved
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: One of the F/A (Flight Attendants) called the flight deck and informed us that there was a Passenger sitting in the aft portion of the aircraft who was behaving strangely but was not yet a problem. We acknowledged and told the F/A to keep us informed of the situation and if it became more of a problem. As time went on; the situation did indeed escalate and it went from the individual in question behaving strangely to becoming much more belligerent; such as being loud and obnoxious; using profanity; making loud comments to other Passengers that made no sense; and eventually refusing to comply with F/A`s instructions. At that point; we were now in Threat Level 1. During this time; we had already started our descent; so we continued to our destination. Unfortunately; events in the cabin escalated even further and eventually became physical and the disruptive Passenger had to be restrained with the use of the aircraft restraint cuffs. We were then in Threat Level 2. This was apparently a free for all encounter by the F/A`s account and it took an off duty commuting Company FFDO (Federal Flight Deck Officer) Pilot; a Law Enforcement Officer who was onboard; and possibly two or three other individuals; some of whom had law enforcement experience to subdue this individual. We had previously informed Dispatch and destination Station operations of our situation and they were prepared for us with ample Law Enforcement Officers; Medical Personnel; and Station Representatives as we pulled into the gate. The individual was removed from the aircraft without incident and the F/A's were polled as to their mental frame of mind for our return flight to XXX. Though somewhat startled; they all felt they were up mentally for the return flight to XXX; so we proceeded as planned. To my knowledge; no one was actually physically injured during this event; and destination operations later informed me that the disruptive Passenger had been taken to a local hospital for a mental evaluation.


Second narrative: Late in the flight; the F/A (Flight Attendant) contacted us on interphone. As Pilot Monitoring; I took the call; and the Captain was monitoring the communication. The F/A (the A) told us they had a non-cooperative Passenger and described his behavior as pacing the aisles and being very vocal. At that point; the Captain jumped in to manage the situation; and I was prepared to be both Pilot Monitoring and Pilot Flying; but still monitored the cabin situation.The A F/A mentioned the disruptive Passenger was seated in one of the last rows next to an elderly couple and she had enlisted their aid to calm him. The Captain and I discussed it briefly; and our extra resources. In addition to the elderly couple; we had at least two able bodied Passengers: an armed Law Enforcement Officer (LEO) and a commuting Company Captain who was also an FFDO (Federal Flight Deck Officer). It sounded like the situation was under control.The timing of the flight was such that I had about ten minutes from the hourly ATIS update and Top Of Descent; and it was time to start getting landing information together for Arrival and Approach Briefings. At about that time; the A Flight Attendant called again to say the situation had escalated into a physical confrontation; and they were going to get restraints on the Passenger with aid of the able-bodied Passengers.The Captain and I discussed again; and I sent via ACARS a message to Dispatch that we would need Law Enforcement upon arrival; we had a commuting Pilot plus onboard LEO for help; the situation was under control; and we had a restrained Passenger. Very shortly after that we received a call from the F/A stating the Passenger had broken the restraints; an altercation broke out; and several Passengers had come to their aid; and possible minor injuries. The F/A (in the confusion I don't know which one it was) was very stressed and nearly in tears.The Captain and I discussed an ATC notification. In as much as we were on a straight-in approach to a non-busy airport; we agreed there was little to be gained by asking for priority at that time. We were becoming task-saturated as it was. Instead; the plan was to inform Tower Control at initial contact to get an immediate taxi to the gate after landing.Dispatch had requested more information via ACARS. Since typing on ACARS is slow and we were then within radio range of destination operations; I called them directly on VHF2 to verify Law Enforcement summons and request Paramedics for possible Passenger injuries. The person on the radio was not yet aware of our situation; so I briefed them quickly. As an FFDO I rechecked my equipment in the event that I would need to defend the flight deckThe approach went normally and I notified Tower of our need for taxi priority upon landing; which they approved. I started the APU on short final as a precaution. The Captain flew the aircraft and landing went normally and we proceeded off the high-speed and directly to Gate XX. Law Enforcement was on hand and I think Paramedics were too.


Synopsis: A B737 flight crew reported a serious unruly passenger incident while at cruise altitude. The individual was subdued; and the flight continued to the destination airport; where law enforcement personnel were waiting.