# NTSB WPR12LA144: Boeing 737-7H4, N247WN, Laverne, OK, March 20, 2012 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: March 20, 2012, 08:30 local (13:30 UTC) - Place: Laverne, OK - Coordinates: 36.700466, -99.889244 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.7005&lon=-99.8892&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Turbulence encounter](https://openairdocs.org/ntsb-events/360) - Highest injury: Serious injuries - Injuries: 1 serious, 141 uninjured - Status: Completed, report October 29, 2013 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - CMO, Southwest Airlines - NTSB case key (mKey): 83196 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR12LA144 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/83196/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=83196 - Page: https://openairdocs.org/ntsb/WPR12LA144 ## Probable cause The airplane’s encounter with severe turbulence during cruise flight, which resulted in a serious injury to a flight attendant. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Turbulence: clear air turbulence](https://openairdocs.org/ntsb-findings/03032015): Environmental issues › Conditions/weather/phenomena · Effect on personnel (probable cause); cases with it: [Boeing 737-7H4, 7 cases](https://openairdocs.org/ntsb-findings/03032015/cases.md?model=1384404), [All aircraft, 78 cases](https://openairdocs.org/ntsb-findings/03032015/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Turbulence encounter](https://openairdocs.org/ntsb-events/360) (defining event); cases with it: [Boeing 737-7H4, 16 cases](https://openairdocs.org/ntsb-events/360/sequence.md?model=1384404), [All aircraft, 423 cases](https://openairdocs.org/ntsb-events/360/sequence.md) ## Analysis The flight had been experiencing moderate turbulence along its route. Once the turbulence had subsided, the seatbelt sign was turned off. The flight attendants had resumed their service when the flight encountered three additional turbulence jolts. The aft galley flight attendant was trying to get seated and strapped into the jumpseat but was injured when another turbulence jolt occurred. She was thrown across the galley and hit her back/ribs on an object. Flight data recorder information showed that vertical accelerations fluctuated between about 0.75 g and 1.2 g; lateral accelerations also fluctuated during this period, between about +/- 0.05 g. An airmen’s meteorological information advisory for moderate turbulence was active for the accident location at the time. A significant meteorological information advisory for occasional severe turbulence was active for an area west of the accident location. ## Factual narrative HISTORY OF FLIGHT On March 20, 2012, at 0830 central daylight time, a Boeing 737-7H4, N247WN, experienced turbulence during cruise flight near Laverne, Oklahoma. Southwest Airlines operated the airplane as Flight 162 under the provisions of 14 Code of Federal Regulations Part 121. The flight crew, 2 flight attendants, and 137 passengers were not injured; 1 flight attendant sustained serious injuries. The airplane was not damaged. An instrument flight rules (IFR) flight plan had been filed for the flight that departed Tampa International Airport (TPA), Tampa, Florida, at 0653 eastern daylight time. The flight was destined for Phoenix Sky Harbor International Airport (PHX), Phoenix, Arizona. According to Southwest Airlines, the airplane was in cruise flight over Laverne when it encountered three turbulence jolts. The aft galley flight attendant was injured while trying to get seated and strapped into the jump seat when another turbulence jolt occurred. The flight attendant was able to perform all required safety duties for the remainder of the flight, but reported significant back pain upon arrival to Phoenix. The flight attendant was not transported to a hospital. On March 22, the flight attendant informed the company that she had been diagnosed with a rib fracture. In statements submitted by the flight attendants, they reported that there was a long duration of turbulence during cruise. When the turbulence diminished, the seatbelt sign was turned off. They got up and then it started to become turbulent again. As the two flight attendants in the back of the airplane attempted to secure themselves in the aft jumpseats, one of them was thrown across the galley and hit her back/ribs on an object. FLIGHT RECORDERS Data obtained from the flight data recorder (FDR) showed that the airplane climbed to flight level 380 shortly after departure. About 0824, winds aloft speed calculated by the flight management computer (FMC) was about 140 knots from about 160 degrees true. For about 5 minutes around this time at flight level 380, vertical accelerations fluctuated between about 0.75g and 1.2g; lateral accelerations also fluctuated during this period, between about +/- 0.05g. At 0827, the airplane descended from flight 380 to flight level 340. Shortly after the descent began, the fluctuations in vertical and lateral accelerations decreased, fluctuating between 0.997g and 1.004g and +/- 0.01g, respectively. After 9 minutes at flight level 340, during the period of otherwise decreased vertical and lateral accelerations, the vertical acceleration varied from about 0.255g to 1.7g within a 1-second period of time at 08:38:20. About 20 minutes after this vertical acceleration encounter, the FMC calculated a decrease in winds aloft at flight level 320 to under 30 knots for about 12 minutes; during this 12-minute period the winds aloft shifted from about 160 degrees true to 340 degrees true. Because this was not determined to be an accident until 2 days after theevent, the cockpit voice recorder information was written over by normal use. METEOROLOGICAL INFORMATION A Senior Meteorologist completed a weather study. A 250-hectopascal (hPa) analysis chart obtained from the Storm Prediction Center and valid for 0700 central daylight time (CDT) identified a portion of a jet stream stretching north from central Texas into Canada. A jet streak (localized regions of very fast winds embedded within the jet stream) was identified in the vicinity of the accident location with southerly wind magnitudes greater than 150 knots. Calculations by the Rawinsonde Observation Program (RAOB) indicated the potential for significant clear-air turbulence between about 36,000 and 40,000 feet. An Airmen’s Meteorological Information (AIRMET) advisory for moderate turbulence between FL220 and FL430 was issued at 0525 CDT and was active for the accident location at the accident time. A Significant Meteorological Information (SIGMET) advisory for occasional severe turbulence between FL330 and FL380 was issued at 0526 CDT for an area west of the accident location. This SIGMET was valid until 0926 CDT. ## Aircraft - Registration: [N247WN](https://openairdocs.org/aircraft/N247WN), registered now, S/N 32508, built 2006 (OpenAirDocs) - Reported make and model: BOEING 737-7H4 - Registry model: [Boeing 737-7H4](https://openairdocs.org/model/boeing-737-7h4) (registry code 1384404) (OpenAirDocs) - Registry engine: [CFM International CFM56-7B24 series](https://openairdocs.org/engine/cfm-international-cfm56-7b24-series) (registry code 13044, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 32508 - Airframe hours: 20917 - Engines: CFM INTL CFM56-7B24 24200 lbs thrust turbo fan; CFM INTL CFM56-7B24 24200 lbs thrust turbo fan - Damage: No damage - Flight: Part 121 - Operator: Southwest Airlines Co - Registered owner: Southwest Airlines Co - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, March 15, 2012, 103 hours before - Departed: TPA, Tampa, FL - Destination: PHX, Phoenix, AZ - Flight plan: IFR - Airport: WWR, West Woodward Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 47; injuries: none; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review February 3, 2012; seat: left; flight hours: 23,050 total, 18,050 in this make and model, 17,350 as pilot in command, 189 in the last 90 days, 83 in the last 30 days, 6 in the last 24 hours - Co-pilot; age 42; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review September 9, 2011; seat: right; flight hours: 7,997 total, 3,622 in this make and model, 2,810 as pilot in command, 143 in the last 90 days, 19 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 140° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 46 °F, dew point 43 °F - Altimeter: 29.72 inHg - Observed at: WWR, 26 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20120320006269A](https://openairdocs.org/incident/20120320006269A), Mar 20, 2012: Boeing 737-7H4, Laverne, OK, No damage. While in cruise flight near Laverne, OK the flight encountered three moderate turbulence jolts (O51 and kwwr appear to be close to the turbulence location… ## Other investigations on N247WN (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB DCA25LA197](https://openairdocs.org/ntsb/DCA25LA197), May 2, 2025: Boeing 737 (N247WN), Centerville, TN, substantial damage. Probable cause: An encounter with hail during descent. ## Docket (7 files) The files NTSB released with the investigation on August 7, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=83196. 12.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40397124&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Flight Data Recorder 10 - Specialist's Factual Report (item 2, .PDF, 274 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40372384&FileExtension=.PDF&FileName=Flight%20Data%20Recorder%2010%20-%20Specialist%27s%20Factual%20Report-Master.PDF - Flight Data Recorder 10 - Attachment 1 - Tabular Data - Flight - (CSV Format-Compressed (Zip Format)) (item 3, ZIP, 4.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40372386&FileExtension=zip&FileName=Flight%20Data%20Recorder%2010%20-%20Attachment%201%20-%20Tabular%20Data%20-%20Flight%20-%20(CSV%20Format-Compressed%20(Zip%20Format))-Master - Flight Release and Weather (item 4, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40397123&FileExtension=.PDF&FileName=Flight%20Release%20and%20Weather-Redacted.PDF - Crew Statements (item 5, .PDF, 44 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40391481&FileExtension=.PDF&FileName=Crew%20Statements-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 6, .PDF, 353 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40391483&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Meteorology 5 - Weather Study (item 7, .PDF, 3.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40398087&FileExtension=.PDF&FileName=Meteorology%205%20-%20Weather%20Study-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.