# NTSB CEN12LA166: Boeing 737-832, N374DA, Detroit, MI, February 19, 2012 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: February 18, 2012, 19:00 local (Feb 19, 2012, 01:00 UTC) - Place: Detroit, MI - Coordinates: 42.350753, -83.059837 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=42.3508&lon=-83.0598&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach: Turbulence encounter](https://openairdocs.org/ntsb-events/360) - Highest injury: Serious injuries - Injuries: 1 serious, 3 minor, 132 uninjured - Status: Completed, report February 27, 2013 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Delta Airlines - NTSB case key (mKey): 82945 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN12LA166 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/82945/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=82945 - Page: https://openairdocs.org/ntsb/CEN12LA166 ## Probable cause An in-flight encounter with forecasted turbulence, which resulted in a serious injury to a flight attendant. Contributing to the accident was the flight attendant not being seated with her seatbelt fastened when the encounter occurred. ## 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 · Contributed to outcome (probable cause); cases with it: [Boeing 737-832, 1 case](https://openairdocs.org/ntsb-findings/03032015/cases.md?model=13844CF), [All aircraft, 78 cases](https://openairdocs.org/ntsb-findings/03032015/cases.md) - [Communication (personnel): following instructions](https://openairdocs.org/ntsb-findings/02063537): Personnel issues › Task performance · Cabin crew (probable cause); cases with it: [Boeing 737-832, 1 case](https://openairdocs.org/ntsb-findings/02063537/cases.md?model=13844CF), [All aircraft, 31 cases](https://openairdocs.org/ntsb-findings/02063537/cases.md) - [Equipment/furnishings: passenger compartment equip](https://openairdocs.org/ntsb-findings/01022520): Aircraft › Aircraft systems · Not used/operated (probable cause); cases with it: [Boeing 737-832, 1 case](https://openairdocs.org/ntsb-findings/01022520/cases.md?model=13844CF), [All aircraft, 24 cases](https://openairdocs.org/ntsb-findings/01022520/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach: Turbulence encounter](https://openairdocs.org/ntsb-events/360) (defining event); cases with it: [Boeing 737-832, 2 cases](https://openairdocs.org/ntsb-events/360/sequence.md?model=13844CF), [All aircraft, 423 cases](https://openairdocs.org/ntsb-events/360/sequence.md) ## Analysis The flight crew received a preflight weather report as well as updated weather information while en route that advised them of expected turbulence near their destination airport. The National Weather Service issued multiple in-flight weather advisories current for the destination area including a significant meteorological advisory for occasional severe turbulence between 22,000 and 30,000 feet. As a result, the flight crew advised the cabin crew that service would have to be completed prior to entering the area of expected turbulence. As the flight approached its destination, the flight crew made an announcement for passengers and cabin crew to remain seated and make sure their seatbelts were fastened. The flight encountered severe turbulence while descending through 29,000 feet mean sea level, and one flight attendant, who did not have her seatbelt fastened, received serious injuries, and two flight attendants and one passenger, who also did not have their seatbelts fastened, received minor injuries. According to the flight data recorder data (FDR), during the event, the maximum vertical acceleration was + 1.568 Gs and the minimum was -0.30 Gs over a time period of 0.625 seconds; these vertical accelerations are considered severe, per International Civil Aviation Organization standards. The accident site was located within the area of moderate to severe turbulence potential. ## Factual narrative On February 18, 2012, about 1900 central standard time, a Boeing 737-832, N374DA, encountered turbulence while descending through 29,000 feet as it approached the Detroit Metropolitan Wayne County Airport (DTW), Detroit, Michigan. Delta Airlines operated flight 1806 under the provisions of 14 Code of Federal Regulations Part 121 as a scheduled domestic passenger flight. Two flight attendants and one passenger sustained minor injuries, and one flight attendant sustained serious injuries. The captain, first officer, another flight attendant, and 129 passengers were not injured. The airplane was not damaged. Visual meteorological conditions prevailed, and the flight was operating on an instrument flight rules (IFR) flight plan. The flight departed the Los Angeles International Airport (LAX), Los Angeles, California and was en route to Detroit, Michigan. The flight crew reported that they received reports of turbulence near DTW and informed the cabin crew to plan on completing having cabin service prior to starting the descent into DTW. The flight attendants reported that they had completed service and were doing their final checks before the approach to DTW. The flight crew also stated that about 2 minutes prior to entering the area of expected turbulence, they made an announcement to the passengers and crew to remain seated and make sure the seatbelts were fastened. The flight attendants stated that the airplane hit turbulence before they were expecting it, and before they could get seated. The first officer reported that as they descended from flight level 290, the airplane encountered a significant jolt of moderate turbulence. The flight encountered decreasing turbulence as they descended before reaching smooth air below flight level 190. According to the flight data recorder data (FDR), during the event, the maximum vertical acceleration was + 1.568 G’s and the minimum was -0.30 G’s over a time period of 0.625 seconds. The FDR data indicated that vertical accelerations were severe, as defined by International Civil Aviation Organization (ICAO) standards. A weather study was conducted by an NTSB meteorologist. According to the study, the High level Significant Weather Prognostic chart depicted the polar jet stream moving northeastward form Texas into Ohio then eastward into the ridge with the maximum wind of 180 knots at 35,000 feet, wind of 70 knots and greater associated with the jet stream extended from 17,000 to 51,000. A second subtropical jet stream was located south of the first jet stream. A large area of moderate turbulence was forecasted with the polar jet stream from Missouri,Iowa, Illinois, Wisconsin, Michigan, Indiana, and Ohio. The chart also expected another area of moderate to severe turbulence from 25,000 to 32,000 feet with the larger area over northern Missouri, Illinois, Iowa, Wisconsin, and Michigan. The accident site was located within the area of moderate to severe turbulence potential. The National Weather Service (NWS)also issued multiple in-flight weather advisories current for the area including a significant meteorological (SIGMET) advisory for occasional severe turbulence between 22,000 and 30,000 feet, a Center Weather Advisory (CWA) and airman meteorological (AIRMET) advisory for moderate turbulence between 18,000 and 41,000 feet. The Delta Meteorology Department provided the flight crew with weather documents for the intended route; the document included several weather alerts for turbulence along the route of flight, the crew also received updates en route via ACARS (Aircraft Communications Addressing and Reporting System). The first update at 1547 CST warned of light to moderate, turbulence. At 1559 CST the advisory was updated to include parts of Ohio and Michigan and advised to avoid altitudes form flight level 200 to 250 for moderate to severe turbulence and moderate turbulence between flight level 260 to 300. Another ACARS message was sent at 1929 CST that indicated the area of moderate to severe turbulence had moved south and east of Detroit. ## Aircraft - Registration: [N374DA](https://openairdocs.org/aircraft/N374DA), registered now, S/N 29622, built 1998 (OpenAirDocs) - Reported make and model: BOEING 737-832 - Registry model: [Boeing 737-832](https://openairdocs.org/model/boeing-737-832) (registry code 13844CF) (OpenAirDocs) - Registry engine: [CFM International CFM56 series](https://openairdocs.org/engine/cfm-international-cfm56-series) (registry code 13802, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 29622 - Airframe hours: 38815 - Engines: CFM INTL. CFM56 SERIES 26000 lbs thrust turbo fan; CFM INTL. CFM56 SERIES 2200 horsepower turbo fan - Damage: No damage - Flight: Part 121 - Operator: Delta Air Lines Inc - Registered owner: Delta Air Lines Inc - Airworthiness certificate: Standard, Transport - Last inspection: AAIP, February 12, 2012 - Departed: LAX, Los Angeles, CA - Destination: DTW, Detroit, MI - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 60; injuries: none; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review October 8, 2011; seat: left; flight hours: 16,205 total, 14,620 in this make and model, 212 in the last 90 days - Co-pilot; age 46; injuries: none; airline transport; airplane ratings: single-engine sea, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review October 6, 2011; seat: right; flight hours: 2,627 total, 2,195 in this make and model, 130 in the last 90 days, 7 in the last 24 hours ## 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 20120218003809A](https://openairdocs.org/incident/20120218003809A), Feb 18, 2012: Boeing 737-832, Detroit, MI, No damage. Aircraft encountered mod. Turb. (Forecasted) on descent into the detriot mi. Area. Three pa's and two interphone announcements reguardung the turb were made… ## Docket (5 files) The files NTSB released with the investigation on January 7, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=82945. 2.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 758 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40383235&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Pilot statements (item 2, .PDF, 37 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40383236&FileExtension=.PDF&FileName=Pilot%20statements-Redacted.PDF - crew statements (item 3, .PDF, 194 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40383237&FileExtension=.PDF&FileName=crew%20statements-Redacted.PDF - Meteorology 5 - Factual Report of Group Chairman (item 4, .PDF, 746 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40367095&FileExtension=.PDF&FileName=Meteorology%205%20-%20Factual%20Report%20of%20Group%20Chairman-Master.PDF - Meteorology 5 - Attachment 1 Weather document & Flight Plan (item 5, .PDF, 245 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40367097&FileExtension=.PDF&FileName=Meteorology%205%20-%20Attachment%201%20Weather%20document%20%26%20Flight%20Plan-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.