DCA16CA181

NTSB accident investigation · Boeing 737 724 · Port Arthur, TX · March 15, 2016

Accident · Serious injuriesData collectionFinal report
Date
March 14, 2016, 21:56 local (Mar 15, 2016, 02:56 UTC)
Place
Port Arthur, TX
Injuries
1 serious, 133 uninjured
Damage
No damage
Phase of flight
Enroute
Aircraft
N23708Boeing 737 724
Defining event
Enroute-cruise: Clear air turbulence encounter
Weather
Visual (VMC) · Night
Status
Completed · report April 22, 2020
Report
Approved by Office Director
NTSB office
Major Investigations Division
Parties
United Airlines
FAA report
20160314003289A
Case key
93343

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

On this page

Probable cause

an inadvertent encounter with clear air turbulence.

Findings · 1

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Turbulence: clear air turbulenceEnvironmental issues › Conditions/weather/phenomena · Effect on personnelBoeing 737-724: 1 caseAll aircraft: 78 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

On March 14, 2016, 2156 central daylight time, United Airlines flight 898,a Boeing 737-724, N23708, encountered turbulence during cruise that resulted in one flight attendant sustaining a serious injury near Port Arthur, Texas. There were no injuries to the other passengers and crew aboard and the airplane was not damaged. The flight was operating under the provisions of 14 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight from the George Bush Intercontinental Airport (IAH), Houston, Texas to the Louis Armstrong New Orleans International Airport (MSY), New Orleans, Louisiana. According to flight crew statements, the captain was the flying pilot and the first officer (FO) was the pilot monitoring. The airplane was level at flight level (FL) 270, with the autopilot off, in clear air with no convective activity in the vicinity. Immediately before before beginning the descent into IAH, the flight encountered a momentary pocket of moderate to severe turbulence with the airplane banking approximately 25 – 30 degrees to the right, and the altitude fluctuating from 100 feet up to 60 - 160 feet down. The flight crew did not recall seeing anything on the onboard weather radar or TCAS (traffic collision avoidance system). The captain immediately turned on the seat belt sign and made an announcement on the public address for the passengers to fasten their seat belts. Shortly after, the flight crew were informed that a flight attendant FA was injured. The captain called the cabin and was informed that one of the FAs was severely injured. The flight crew declared a medical emergency and arranged for paramedics to meet the flight at the gate. The FA was transported to a local hospital and diagnosed with serious injuries. According to a weather analysis conducted by United Airlines, satellite imagery indicated no significant cloud features over the route of flight, with the moisture channel imagery indicating moisture channel darkening or drier air in the middle tropospheric levels across the northern half of Texas and southern Los Angeles with increasing moisture further to the south with the stronger jet stream winds. A review of pilot reports (PIREPs) across the region leading up to the turbulence only indicated light turbulence being encountered. Consequently, The Weather Company forecasts only called for light turbulence for the route. However, several Aircraft Meteorological Data and Reporting (AMDAR) automated reports across the region indicated that winds were stronger than predicted at higher levels and indicated a strong vertical wind shear at higher levels than originally forecast.

Factual narrative

On March 14, 2016, 2156 central daylight time, United Airlines flight 898,a Boeing 737-724, N23708, encountered turbulence during cruise that resulted in one flight attendant sustaining a serious injury near Port Arthur, Texas. There were no injuries to the other passengers and crew aboard and the airplane was not damaged. The flight was operating under the provisions of 14 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight from the George Bush Intercontinental Airport (IAH), Houston, Texas to the Louis Armstrong New Orleans International Airport (MSY), New Orleans, Louisiana. According to flight crew statements, the captain was the flying pilot and the first officer (FO) was the pilot monitoring. The airplane was level at flight level (FL) 270, with the autopilot off, in clear air with no convective activity in the vicinity. Immediately before before beginning the descent into IAH, the flight encountered a momentary pocket of moderate to severe turbulence with the airplane banking approximately 25 – 30 degrees to the right, and the altitude fluctuating from 100 feet up to 60 - 160 feet down. The flight crew did not recall seeing anything on the onboard weather radar or TCAS (traffic collision avoidance system). The captain immediately turned on the seat belt sign and made an announcement on the public address for the passengers to fasten their seat belts. Shortly after, the flight crew were informed that a flight attendant FA was injured. The captain called the cabin and was informed that one of the FAs was severely injured. The flight crew declared a medical emergency and arranged for paramedics to meet the flight at the gate. The FA was transported to a local hospital and diagnosed with serious injuries. According to a weather analysis conducted by United Airlines, satellite imagery indicated no significant cloud features over the route of flight, with the moisture channel imagery indicating moisture channel darkening or drier air in the middle tropospheric levels across the northern half of Texas and southern Los Angeles with increasing moisture further to the south with the stronger jet stream winds. A review of pilot reports (PIREPs) across the region leading up to the turbulence only indicated light turbulence being encountered. Consequently, The Weather Company forecasts only called for light turbulence for the route. However, several Aircraft Meteorological Data and Reporting (AMDAR) automated reports across the region indicated that winds were stronger than predicted at higher levels and indicated a strong vertical wind shear at higher levels than originally forecast.

Aircraft

Registration
N23708
Reported as
Boeing 737 724 (724)
Category
Airplane
Serial number
28769
Built
1998
Engines
CFM Intl. CFM56 SERIES, turbo fanCFM Intl. CFM56 SERIES, turbo fan
Damage
No damage
Flight
Part 121
Operator
United Airlines
Registered owner
Wells Fargo Bank Northwest Na Trustee
Airworthiness certificate
Standard, Transport
Departed
IAH · Houston, TX
Destination
MSY · New Orleans, LA
Flight plan
IFR
Equipment
Onboard weather, Stall warning system, ADS-B, Angle of attack indicator, Auto-pilot, Data recorder, Electronic flight bag or handheld device, Electronic multifunction display, Electronic primary flight display

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew · 2

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
49
Injuries
None
Certificate
Airline transport
Airplane ratings
Multi-engine land
Instrument ratings
Airplane
Medical
Class 1
Seat
Left
Restraint
5-point
Flight hours
11,000 total · 7,000 in this make and model
Role
Co-pilot
Age
45
Injuries
None
Certificate
Airline transport
Airplane ratings
Multi-engine sea
Instrument ratings
Airplane
Medical
Class 1
Seat
Right
Restraint
5-point
Flight hours
5,000 in this make and model · 5 in the last 24 hours

Weather

Conditions
Visual (VMC) · Night
Wind
270° at 40 knots
Lowest ceiling
None
Turbulence
Severe

Docket · 5

The files NTSB released with the investigation on July 21, 2021, on NTSB’s docket system: statements, records, photos and specialists’ reports. 13.1 MB in all.

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.

Other investigations on N23708 · 1

Matched to the same aircraft by N-number and date.