# NTSB DCA19CA169: Boeing 737, N75436, Denver, CO, June 9, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 4 · Data collection · Final report - Date: June 9, 2019, 15:55 local (21:55 UTC) - Place: Denver, CO - Coordinates: 39.856109, -104.673614 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.8561&lon=-104.6736&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-flare/touchdown: Tailstrike](https://openairdocs.org/ntsb-events/091) - Highest injury: No injuries - Injuries: 184 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Major Investigations Division - NTSB case key (mKey): 99668 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA19CA169 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99668/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99668 - Page: https://openairdocs.org/ntsb/DCA19CA169 ## Probable cause the early initiation of the landing flare that resulted in a high pitch attitude and tailstrike. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Copilot (probable cause); cases with it: [Boeing 737-924ER, 1 case](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=13848A3), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Flight crew; cases with it: [Boeing 737-924ER, 2 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=13848A3), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-flare/touchdown: Tailstrike](https://openairdocs.org/ntsb-events/091) (defining event); cases with it: [Boeing 737-924ER, 3 cases](https://openairdocs.org/ntsb-events/091/sequence.md?model=13848A3), [All aircraft, 124 cases](https://openairdocs.org/ntsb-events/091/sequence.md) ## Analysis On June 9, 2019, about 1555 MDT, United Airlines flight 401, a B737-924ER, N75436, experienced a tailstrike during landing at Denver International Airport (DEN), Denver, Colorado. There were no injuries to the 184 passengers and crew onboard. The airplane received substantial damage. The regularly scheduled domestic passenger flight was operating under 14 Code of Federal Regulations Part 121 from Reno International Airport (RNO), Reno, Nevada to DEN. The first officer (FO) was the pilot flying and the captain was the pilot monitoring. During short final, the FO noticed he was about 5 knots fast, and about 50 feet above the runway, started to slowly reduce power and start the landing flare. At touchdown the airplane bounced. The FO was about to advance throttles for a go-around, when the captain took control and continued the landing after a second bounce. During the post flight walk around, the flight crew observed that the lower aft fuselage had sustained damaged due to a tailstrike. Maintenance examination of the airplane found that the tailskid cartridge was compressed and there was substantial damage to the fuselage skin, frames, stringer clips and shear ties between fuselage station 827 to 907 and deformed stringers 27L and 27R. ## Aircraft - Registration: [N75436](https://openairdocs.org/aircraft/N75436), registered now, S/N 33531, built 2009 (OpenAirDocs) - Reported make and model: Boeing 737 (924ER) - Registry model: [Boeing 737-924ER](https://openairdocs.org/model/boeing-737-924er) (registry code 13848A3) (OpenAirDocs) - Registry engine: [CFM International CFM56-7B26/3 series](https://openairdocs.org/engine/cfm-international-cfm56-7b26-3-series) (registry code 13073, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 33531 - Year built: 2009 - Airframe hours: 33901 - Engines: GE CFM56-7B turbo fan; GE CFM56-7B turbo fan - Damage: Substantial damage - Flight: Part 121 - Operator: United Air Lines Inc - Registered owner: United Airlines Inc - Airworthiness certificate: Standard, Transport - Last inspection: May 31, 2019 - Departed: KRNO, Reno, NV - Destination: KDEN, Denver, CO - Flight plan: IFR - Airport: DEN, Denver Intl, runway 16R, 16,000 × 200 ft, asphalt - Equipment: Electronic primary flight display, Onboard weather, Stall warning system, Data recorder, Electronic flight bag or handheld device, Electronic multifunction display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 54; injuries: none; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review October 12, 2018; seat: left; restraint: 5-point; flight hours: 15,041 total, 3,139 in this make and model, 5,089 as pilot in command, 174.6 in the last 90 days, 38.2 in the last 30 days, 4.2 in the last 24 hours - Co-pilot; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land, single-engine sea; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review May 20, 2019; seat: right; restraint: 5-point; flight hours: 4,500 total, 45 in this make and model, 2,450 as pilot in command, 45.4 in the last 90 days, 44 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 3 knots - Visibility: 10 statute miles - Temperature: 61 °F, dew point 36 °F - Altimeter: 30.45 inHg - Observed at: KDEN ## Docket (5 files) The files NTSB released with the investigation on April 1, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99668. 4.0 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 432 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9757114&FileExtension=pdf&FileName=6120.1_UA401-09JUN%20-%20Tailstrike,%20Substantial%20Damage-Rel.pdf - Photo of damage to aircraft (item 2, JPG, 92 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13345705&FileExtension=JPG&FileName=Tailstrike_Aircraft%20Damage_AC0436-Rel.JPG - United damage assessment (item 3, PDF, 22 pages, 3.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9759379&FileExtension=pdf&FileName=United%20Airlines%20Engineering_AC%200436%20Damage%20Assessment_Final-Rel.pdf - Captain statement (item 4, PDF, 1 page, 32 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9759316&FileExtension=pdf&FileName=UA401-09JUN%20-%20Tailstrike,%20Substantial%20Damage_CA%20Statement-Rel.pdf - Fo statement (item 5, PDF, 1 page, 30 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9759601&FileExtension=pdf&FileName=UA401-09JUN%20-%20Tailstrike,%20Substantial%20Damage_FO%20Statement-Rel.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.