Incident Overview
On March 14, 2016, at 2156 central daylight time, United Airlines Flight 898, a Boeing 737-724 (registration N23708), experienced turbulence while in cruise flight near Port Arthur, Texas. The flight was operating as a scheduled passenger service under 14 CFR Part 121 from George Bush Intercontinental Airport (IAH) in Houston, Texas, to Louis Armstrong New Orleans International Airport (MSY) in New Orleans, Louisiana.
Flight Crew Account
According to statements from the flight crew, the captain was the pilot flying, and the first officer was the pilot monitoring. The aircraft was level at flight level 270, with the autopilot disengaged, in clear air with no convective activity in the vicinity. Just before beginning the descent into IAH, the flight encountered a momentary pocket of moderate to severe turbulence. During this event, the airplane banked approximately 25 to 30 degrees to the right, and altitude fluctuated from 100 feet up to 60 to 160 feet down. The flight crew did not recall any indications on the onboard weather radar or Traffic Collision Avoidance System (TCAS). The captain immediately activated the seat belt sign and made a public address announcement instructing passengers to fasten their seat belts. Shortly thereafter, the crew was notified that a flight attendant had been injured. The captain contacted the cabin and learned that the flight attendant was severely injured. The flight crew declared a medical emergency and arranged for paramedics to meet the aircraft at the gate. The injured flight attendant was transported to a local hospital and diagnosed with serious injuries.
Weather Analysis
United Airlines conducted a weather analysis using satellite imagery, which indicated no significant cloud features over the route. Moisture channel imagery showed drying air in the middle tropospheric levels across the northern half of Texas and southern Louisiana, with increasing moisture further south where stronger jet stream winds were present. A review of pilot reports (PIREPs) from the region leading up to the incident indicated only light turbulence. Consequently, forecasts from The Weather Company called only for light turbulence along the route. However, several Aircraft Meteorological Data and Reporting (AMDAR) automated reports showed that winds were stronger than predicted at higher altitudes, indicating strong vertical wind shear at levels higher than initially forecast.