B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Type 1423
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Flight Deck / Cabin / Aircraft Event Illness / Injury; Flight Deck / Cabin / Aircraft Event Passenger Misconduct; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Regained Aircraft Control; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification
Weather
Pre-brief. I briefed and directed all flight attendants to remain seated until I called to allow them to begin service. I also reviewed the [turbulence guidance] commands and procedures with all flight attendants together. This occurred in the [gate] jetway prior to boarding the airplane and was driven by the unusual [local] weather.Pre-departure passenger announcements. I personally greeted the passengers in first class and explained directly the flight attendants would delay their service to them as much as 20-30 minutes. I made a PA announcement to the entire airplane while standing near Row 1 so all passengers could see me. During this welcome announcement I stated; 'When I turn on the seatbelt sign; I'm serious! Don't get up. If you wake and see the sign is on; stay seated. This is for your safety and the safety of my flight attendants.' This announcement is standard for me; and I vary it only as conditions differ from flight to flight.Departure. My FO (First Officer) and I tuned the radar on to view activity to the east while holding short RW XXR. We both varied the tilt and range and concluded we didn't see anything significant in our path out to 160 NM. Turbulence was light to occasional moderate throughout the departure; and we noticed most of the buildups were absent from radar and could see nothing of concern throughout the turn to the east.We were filed 27;000 initially; but ATC advised the smoother rides were higher. We requested 35;000 based on reports and airplane performance. Light and occasional moderate turbulence remained throughout. At level off; we continued to individually assess radar and limited visual cues for storm position; height; and intensity. ATC offered direct ZZZ1; but I declined the offer until we could confirm this routing with dispatch. Based on tilt position and visual cues; it appeared all storm activity was below 35;000 by more than 5;000 feet. However; performance allowed 36;000 so requested and were cleared block 35- to 37;000. We climbed to 36;000. Rather than engage Econ Climb/Cruise; we selected speed 280/.76. The event. At one point the air began to smooth; but could see there was one line of storms remaining. I made the PA announcement for everyone to remain seated and warned we have another set of bumps to pass. As we approached the weather; it appeared to have 'exploded' in front of us and I thought we would be right at the tops. However; within seconds we were completely engulfed and turbulence increased to continuous moderate with occasional severe. I monitor the flight attendants on the interphone routinely. At this time the FA (Flight Attendant) at 2L called the Purser and advised her a woman got up to the lavatory. She also stated that they yelled at her it wasn't safe and to return to her seat. However; the woman continued to the aft lavatory. While she was in the lavatory; turbulence shot up to continuous severe and I disconnected the autopilot to maintain pitch and power (auto throttles remained armed; but I physically guarded them). Airspeed fluctuated from stickshaker to clacker; and altitude dropped to as low as 34;800 feet. Event seemed to last two minutes or more. Once we exited the weather; I confirmed with flight attendants they were good and asked the status of the passenger. They reported they were fine; but the passenger suffered a cut to the forehead. When it was safe for any medical help to leave their seats; Purser requested passengers with medical training to identify themselves. A fire battalion chief and family member fire paramedic responded to the call; treated the woman; and fed information to me that I passed to Medlink. Two male passengers also complained of neck pain. Medlink recommended three Tylenol for each passenger and one Benadryl for the male passenger who vomited. Note: neither Tylenol nor Benadryl are labeled as such in the medical kit and caused confusion to the flight attendants. It took about an hour from the time I could allow first responders to leave their seats to the time I was fed information to pass to Medlink. After several frequency attempts to contact dispatch through ARINC; Medlink confirmation to continue and offer the medication was finally received. Medical personnel met us at the arrival gate and escorted all three injured passengers off the airplane.
B737 Captain reported severe turbulence as well as issues with the medical kit used to administer first aid to passengers injuries.