# NTSB DCA24LA316: Boeing 757-224, N12125, Dunnigan, CA, September 19, 2024 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 4 · Limited · Final report - Date: September 19, 2024, 12:47 local (19:47 UTC) - Place: Dunnigan, CA - Coordinates: 38.9134, -121.961 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.9134&lon=-121.9610&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-descent: Near midair/TCAS alert/loss of separation](https://openairdocs.org/ntsb-events/260) - Highest injury: Serious injuries - Injuries: 2 serious, 2 minor, 151 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Major Investigations Division - Parties: Boeing, FAA, United Airlines - NTSB case key (mKey): 195189 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA24LA316 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/195189/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=195189 - Page: https://openairdocs.org/ntsb/DCA24LA316 ## Probable cause The abrupt pitch control input by the flight crew in response to a TCAS resolution advisory resulted in two serious passenger injuries. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Object/animal/substance: aircraft](https://openairdocs.org/ntsb-findings/03022040): Environmental issues › Physical environment · Effect on equipment; cases with it: [Boeing 757-224, 1 case](https://openairdocs.org/ntsb-findings/03022040/cases.md?model=1384958), [All aircraft, 116 cases](https://openairdocs.org/ntsb-findings/03022040/cases.md) - [Object/animal/substance: aircraft](https://openairdocs.org/ntsb-findings/03022040): Environmental issues › Physical environment · Effect on personnel (probable cause); cases with it: [Boeing 757-224, 1 case](https://openairdocs.org/ntsb-findings/03022040/cases.md?model=1384958), [All aircraft, 116 cases](https://openairdocs.org/ntsb-findings/03022040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-descent: Near midair/TCAS alert/loss of separation](https://openairdocs.org/ntsb-events/260) (defining event); cases with it: [Boeing 757-224, 1 case](https://openairdocs.org/ntsb-events/260/sequence.md?model=1384958), [All aircraft, 96 cases](https://openairdocs.org/ntsb-events/260/sequence.md) - [Enroute-descent: Abrupt maneuver](https://openairdocs.org/ntsb-events/270); cases with it: [Boeing 757-224, 1 case](https://openairdocs.org/ntsb-events/270/sequence.md?model=1384958), [All aircraft, 346 cases](https://openairdocs.org/ntsb-events/270/sequence.md) ## Analysis United Airlines (UA) flight 2428 received a traffic alert and collision avoidance system (TCAS) resolution advisory (RA) while descending to flight level FL310 when enroute to San Francisco International Airport (SFO), San Francisco, California. Two passengers were seriously injured, and two cabin crewmembers sustained minor injuries as a result of the aircraft response to the TCAS alert. The flight was a regularly scheduled domestic passenger flight from Newark Liberty International Airport (EWR), Newark, New Jersey to SFO. UA2428 was instructed by air traffic control to descend and maintain FL310 for their arrival into SFO. About 500 ft above level off at FL310, the crew received a TCAS traffic alert “traffic, traffic” for an aircraft crossing 1,500 feet below to which, the first officer, as pilot flying, reduced vertical speed on the mode control panel in response. A TCAS RA then immediately annunciated for the same traffic. The pilot flying responded by disengaging the autopilot and auto throttle and pitched the aircraft up following the pitch guidance on the primary flight display. Flight data show pitch increased by about 3° over 1 second and the aircraft descent arrested. Vertical acceleration ranged from 2.3 to 0.6 (g) over 2 seconds during the maneuver. The seatbelt sign had been turned on in the cabin shortly prior to the TCAS annunciation, however passengers still remained in the lavatories at the time of the maneuver. Two flight attendants were in the forward galley cleaning in preparation for the initial descent announcement. These two flight attendants fell to the floor during the maneuver and sustained minor injuries. There were two passengers in the aft lavatories at the time of the maneuver. One passenger flew upwards and landed forward fracturing the L2 spinal vertebrae. The other passenger was exiting the lavatory when he flew upwards and landed on his leg resulting in a fractured ankle. Following the event, the aircraft landed uneventfully. Paramedics met the aircraft at the gate and transported the passengers to the hospital for treatment. ## Aircraft - Registration: [N12125](https://openairdocs.org/aircraft/N12125), registered now, S/N 28967, built 1998 (OpenAirDocs) - Reported make and model: BOEING 757-224 - Registry model: [Boeing 757-224](https://openairdocs.org/model/boeing-757-224) (registry code 1384958) (OpenAirDocs) - Registry engine: [Rolls-Royce RB-211 series](https://openairdocs.org/engine/rolls-royce-rb-211-series) (registry code 54555, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 28967 - Year built: 1998 - Airframe hours: 94715 - Engines: ROLLS-ROYC RB-211 SERIES 22000 lbs thrust turbo fan; ROLLS-ROYC RB-211 SERIES 22000 lbs thrust turbo fan - Damage: No damage - Flight: Part 121 - Operator: United Airlines Inc - Registered owner: United Airlines Inc - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, October 6, 2024 - Departed: EWR, Newark, NJ - Destination: SFO, San Fransisco, CA - Flight plan: IFR - Equipment: Angle of attack indicator, Auto-pilot, Data recorder, Electronic flight bag or handheld device, Electronic multifunction display, Electronic primary flight display, Onboard weather, ADS-B, Satellite tracking device, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review May 16, 2024; seat: left; restraint: 5-point; flight hours: 16,899 total, 1,440 in this make and model, 5,936 as pilot in command, 221 in the last 90 days, 64 in the last 30 days - Co-pilot; age 35; injuries: none; airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: helicopter, airplane; medical: class 1, without waivers/limitations; last flight review August 30, 2024; seat: right; restraint: 3-point; flight hours: 2,646 total, 33 in this make and model, 588 as pilot in command, 119 in the last 90 days, 38 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 110° at 15 knots - Temperature: -47 °F ## 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 20240919022419A](https://openairdocs.org/incident/20240919022419A), Sep 19, 2024: Boeing 757-224, Oakland, CA, No damage. On September 19, 2024, [privacy data omitted] declared a medical emergency for passenger injuries after responding to a TCAS ra while descending from FL320 to… ## Other investigations on N12125 (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 DCA22LA002](https://openairdocs.org/ntsb/DCA22LA002), Sep 27, 2021: Boeing 757-224 (N12125), Newark, NJ, substantial damage. Probable cause: The nose high attitude on landing resulted in a tailstrike. ## Docket (5 files) The files NTSB released with the investigation on March 27, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=195189. 34.2 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120 (item 1, PDF, 11 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18532178&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Flight crew statements (item 2, PDF, 2 pages, 102 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18212650&FileExtension=pdf&FileName=Flight%20Crew%20Statements-Rel.pdf - Flight attendant statements (item 3, PDF, 4 pages, 120 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18213145&FileExtension=pdf&FileName=DCA24LA316%20-%20UAL%202428%20EWR-SFO%2019SEPT%20Flight%20Attendant%20Statements_Redacted-Rel.pdf - Flight data recorder - specialist's factual report (item 4, PDF, 10 pages, 3 photos, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18353316&FileExtension=pdf&FileName=Flight%20Data%20Recorder%20-%20Specialist%27s%20Factual%20Report-Rel.pdf - Flight data recorder - specialist's factual report - attachment 1 (item 5, CSV, 30.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18352352&FileExtension=csv&FileName=attachment%201-Rel.csv 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.