# NTSB DCA25LA025: Boeing 737-9, N27515, Houston, TX, October 24, 2024 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 4 · Limited · Final report - Date: October 24, 2024, 12:52 local (17:52 UTC) - Place: Houston, TX - Coordinates: 29.97172, -95.351553 - Nearby events: https://openairdocs.org/map.md?lat=29.9717&lon=-95.3516&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) - Highest injury: No injuries - Injuries: 145 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Major Investigations Division - Parties: United Airlines, FAA - NTSB case key (mKey): 195444 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA25LA025 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/195444/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=195444 - Page: https://openairdocs.org/ntsb/DCA25LA025 ## Probable cause Brake application before all three landing gears were on the ground, which caused the failure of the right main landing gear tires and resulted in tire fragments impacting the fuselage. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: tire casing](https://openairdocs.org/ntsb-findings/01023244): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Boeing 737-9, 1 case](https://openairdocs.org/ntsb-findings/01023244/cases.md?model=138470A), [All aircraft, 36 cases](https://openairdocs.org/ntsb-findings/01023244/cases.md) - [Wing structure: plates/skins (on wing)](https://openairdocs.org/ntsb-findings/01035730): Aircraft › Aircraft structures · Damaged/degraded; cases with it: [Boeing 737-9, 1 case](https://openairdocs.org/ntsb-findings/01035730/cases.md?model=138470A), [All aircraft, 11 cases](https://openairdocs.org/ntsb-findings/01035730/cases.md) - [Action: incorrect action performance](https://openairdocs.org/ntsb-findings/02041015): Personnel issues › Action/decision · Flight crew (probable cause); cases with it: [Boeing 737-9, 2 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md?model=138470A), [All aircraft, 1,386 cases](https://openairdocs.org/ntsb-findings/02041015/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) (defining event); cases with it: [Boeing 737-9, 1 case](https://openairdocs.org/ntsb-events/337/sequence.md?model=138470A), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) - [Landing-landing roll: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338); cases with it: [Boeing 737-9, 2 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=138470A), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis United Airlines flight 1181 experienced a failure of the number 3 and number 4 tires on the right main landing gear (MLG) during landing on runway 26L at George Bush Intercontinental/Houston Airport (IAH), Houston, Texas. The airplane exited the runway and stopped on a high-speed taxiway, and the passengers were deplaned and bussed to the terminal. Post landing inspection revealed substantial damage to the aircraft fuselage skin. The captain was the pilot flying and the first officer (FO) was the pilot monitoring for the entire duration of the flight. During preflight preparations for departure from Harry Reid International Airport (LAS), Las Vegas, Nevada, both pilots reviewed the flight release and noted three Minimum Equipment List (MEL) items: the autobrake system, the antiskid system, and a coffee maker. The autobrake and antiskid systems had been deferred earlier that morning due to maintenance issues, specifically an antiskid alert light that failed to test correctly. Given these deferrals, the crew stated they reviewed the enroute and destination weather conditions and reviewed operational limitations with the MEL items. Weather was visual flight rules (VFR) at both departure and destination airports. The crew determined that all MEL-related limitations were satisfied, including the need for a dry runway, no tailwind, use of flaps 40 for landing, and sufficient landing distance. The aircraft departed LAS without incident. During descent into Houston, the crew stated they conducted the approach briefing, incorporating the limitations due to the MEL items. The FO noted a slight tailwind component on Runway 26L and requested an opposite-direction landing due to the autobrake and antiskid systems not available. However, Houston approach air traffic control (ATC) was unable to accommodate the request due to traffic volume and airspace restrictions. Winds were later reported as calm, and the crew proceeded with a visual approach to Runway 26L. When the FO did a final wind check with the tower, they were informed of a direct left-to-right crosswind relative to the runway, at 8 knots. Both the captain and FO described the landing as soft and initially uneventful. The speed brakes deployed automatically, and the captain stated he applied brakes and activated the thrust reversers. However, shortly after the reversers were deployed, the captain perceived an abnormal condition, suspecting a tire failure due to the unusual noise and slight lateral swaying. The FO described the sensation as skidding followed by grinding and noted that the aircraft did not roll smoothly below 10 knots, with a right-wing-down lean. The captain suspected a blown tire and steered the aircraft off the runway and onto a high-speed taxiway. A review of the FDR data for the landing show that as the pitch angle was reduced, the brake pressure began to rise to about 500 psi, prior to the right MLG air/ground switch changing to “ground”. After the right MLG was on the ground,the brake pressure continued to rise, peaking at about 1500 psi as the left MLG air/ground switch changed to “ground”. Brake pressure then eased to about 1000 psi as the nose gear air/ground switch changed to “ground” and the vertical acceleration peaked at about 1.3g. About one second later, there was a second spike in vertical acceleration to 1.3g, concurrent with an increased roll attitude to about 2 degrees right wing down, consistent with the failure of the right MLG tires. Since the autobraking and antiskid systems were disabled, the flight crew had to manually apply brakes during the landing. The FDR data showed that the brake application happened before all three landing gear had changed to “ground” status, and likely before the wheels had an opportunity to fully spin up. The early application of the brakes during the landing likely contributed to the failure of the tires on the right MLG. The ATC tower reported seeing smoke emanating from the aircraft during rollout, prompting the crew to request emergency vehicles. Upon stopping, ground personnel confirmed that both tires on the right MLG were severely damaged. The crew started the auxiliary power unit (APU), shut down the engines, and completed the after-landing and parking checklists. Passengers were informed of the situation and deplaned via air stairs approximately 40–45 minutes after landing. Buses transported all passengers and crew to the terminal. No injuries were reported. Post landing inspection showed an impact dent on the fuselage above the right MLG. The affected area is identified in the United Airlines structural repair manual (SRM) as a principal structural element and required repair utilizing the techniques identified in the SRM. Inspection of the frames, stringers, and shear ties near the damaged area showed no damage to any adjacent areas. ## Aircraft - Registration: [N27515](https://openairdocs.org/aircraft/N27515), registered now, S/N 43452, built 2020 (OpenAirDocs) - Reported make and model: BOEING 737-9 - Registry model: [Boeing 737-9](https://openairdocs.org/model/boeing-737-9) (registry code 138469A) (OpenAirDocs) - Registry engine: [CFM International LEAP-1B28B series](https://openairdocs.org/engine/cfm-international-leap-1b28b-series) (registry code 13124, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 43452 - Year built: 2020 - Airframe hours: 12085 - Engines: CFM International LEAP-1B28G06 28000 lbs thrust turbo fan; CFM International LEAP-1B28G06 28000 lbs thrust turbo fan - Damage: Substantial damage - Flight: Part 121 - Operator: United Airlines - Registered owner: Wilmington Trust Co Trustee - Airworthiness certificate: Standard, Commuter - Last inspection: Continuous airworthiness, October 9, 2024 - Departed: LAS, Las Vegas, NV - Destination: Same as departure - Flight plan: IFR - Airport: IAH, George Bush Intcntl/Houston, runway 26L, 9,402 × 150 ft, concrete - Equipment: Data recorder, Electronic flight bag or handheld device, Electronic multifunction display, Electronic primary flight display, Onboard weather, Satellite tracking device, Auto-pilot, Stall warning system, ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 58; injuries: none; recreational, commercial, flight instructor, airline transport, sport pilot; airplane ratings: single-engine land, multi-engine land, single-engine sea, multi-engine sea; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review September 5, 2024; seat: left; restraint: 5-point; flight hours: 20,092 total, 4,258 in this make and model, 7,202 as pilot in command, 187 in the last 90 days, 65 in the last 30 days, 2 in the last 24 hours - Co-pilot; age 40; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, powered-lift; medical: class 1, without waivers/limitations; last flight review September 5, 2024; seat: right; restraint: 5-point; flight hours: 3,889 total, 1,563 in this make and model, 1,086 as pilot in command, 130 in the last 90 days, 50 in the last 30 days, 7 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 8 knots - Lowest ceiling: 3,500 ft broken - Temperature: 82 °F - Altimeter: 30.09 inHg - Observed at: KIAH ## 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 20241024022239A](https://openairdocs.org/incident/20241024022239A), Oct 24, 2024: Boeing 737-9, Houston, TX, Substantial damage. On 10/24/2024, aircraft operating from harry reid international airport, las vegas, Nevada (las)- George Bush Intercontinental airport, Houston, Texas (iah).… ## Docket (4 files) The files NTSB released with the investigation on September 23, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=195444. 2.7 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19247388&FileExtension=pdf&FileName=DCA25LA025%206120.1%20-%20Copy4-Rel.pdf - Pilot's statement - captain (item 2, PDF, 2 pages, 20 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19249014&FileExtension=pdf&FileName=UA1181%20DCA25LA025%20NTSB%20Statement%20-%20CA-Rel.pdf - Pilot's statement - first officer (item 3, PDF, 1 page, 27 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19249317&FileExtension=pdf&FileName=UA1181%20DCA25LA025%20NTSB%20Statement%20-%20FO-Rel.pdf - Photo - damage to the principal structural element (pse) (item 4, JPG, 694 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19248777&FileExtension=jpg&FileName=PSE_damage.jpg 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.