# NTSB WPR14LA346: Boeing 737 7H4, N758SW, Salt Lake City, UT, August 14, 2014 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 14, 2014, 09:41 local (15:41 UTC) - Place: Salt Lake City, UT - Coordinates: 40.786388, -111.973052 - Nearby events: https://openairdocs.org/map.md?lat=40.7864&lon=-111.9731&mi=10 - Phase of flight: [Standing](https://openairdocs.org/ntsb-phases/150) (OpenAirDocs' grouping) - Defining event: [Standing-engine(s) not oper: Ground handling event](https://openairdocs.org/ntsb-events/080) - Highest injury: No injuries - Injuries: 5 uninjured - Status: Completed, report July 16, 2018 - Report: Approved by Office Director - NTSB office: Western Pacific Region - NTSB case key (mKey): 89880 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR14LA346 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/89880/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=89880 - Page: https://openairdocs.org/ntsb/WPR14LA346 ## Probable cause The disconnection of baggage carts that subsequently collided with the parked airplane following the tug driving over a dip in the roadway. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info](https://openairdocs.org/ntsb-findings/02063000): Personnel issues › Task performance · Ground crew (probable cause); cases with it: [Boeing 737-7H4, 1 case](https://openairdocs.org/ntsb-findings/02063000/cases.md?model=1384404), [All aircraft, 111 cases](https://openairdocs.org/ntsb-findings/02063000/cases.md) - [Object/animal/substance: ground equipment](https://openairdocs.org/ntsb-findings/03022050): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Boeing 737-7H4, 2 cases](https://openairdocs.org/ntsb-findings/03022050/cases.md?model=1384404), [All aircraft, 52 cases](https://openairdocs.org/ntsb-findings/03022050/cases.md) - [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Effect on operation; cases with it: [Boeing 737-7H4, 1 case](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=1384404), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Standing-engine(s) not oper: Ground handling event](https://openairdocs.org/ntsb-events/080) (defining event); cases with it: [Boeing 737-7H4, 4 cases](https://openairdocs.org/ntsb-events/080/sequence.md?model=1384404), [All aircraft, 108 cases](https://openairdocs.org/ntsb-events/080/sequence.md) ## Analysis The commercial air carrier airplane was parked at the boarding gate with the crew onboard. A tug driver from another airline was pulling four baggage carts in the non-movement area adjacent to the boarding gates. A security video showed that the second cart hit a drain cover and detached from the preceding cart. The loose baggage carts then rolled across the ramp and into the side of the airplane, resulting in substantial damage. There were no injuries. ## Factual narrative On August 14, 2014, about 0941 mountain daylight time, a Boeing 737-700 airplane, N758SW, was struck by a runaway baggage cart while sitting at the boarding gate, at the Salt Lake City International Airport (KSLC), Salt Lake City, Utah. The two airline transport pilots and three cabin crewmembers were not injured. The fuselage was substantially damaged. The airplane was registered to, and operated by, the Southwest Airlines Company, Dallas, Texas, as Southwest Flight 579, as a Title 14 Code of Federal Regulations Part 121 domestic passenger flight. An instrument flight rules flight plan was filed. The airplane was being prepared to board passengers when the event occurred. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on August 14, a representative of the Southwest Airlines Company said that he had been advised of the event in Salt Lake City, and received photographs showing structural damage to the airplane. He said the baggage cart had been on the end of a string of carts being pulled by a tug belonging to Delta Airlines. The cart came loose while being towed and rolled into the airplane, penetrating the side of the fuselage. During a subsequent telephone conversation, a representative of Delta Airlines reported that a tug, belonging to Delta Airlines, had been pulling several baggage carts in the non-movement area adjacent to the airplane boarding gates. She said an airport surveillance video showed the second cart in the string hit a pothole and detached from the preceding cart. The loose baggage carts rolled across the ramp and into the side of the airplane. Prior to the accident, there were no reported mechanical anomalies with the airplane. According to a Salt Lake City Airport Police report, the Delta Employee who drove the event tug stated he was pulling a string of four baggage carts behind his tug, northbound on the airfield road on the east side of the Bravo Concourse. He said he was coming from Gate B-3 heading north to the baggage cart boneyard. He further reported that when he arrived at the boneyard, there was only 1 baggage cart attached to the tug. He did not know when or where the 3 missing carts had detached from the string. A Southwest employee reported to the police that he was pulled up to the rear-belt loader on gate B-17. He detached 2 baggage carts from his tug and got back in his tug. He looked up and saw 3 Delta baggage carts rolling towards the belt-loader. He yelled to his fellow-employee to watch out, and the baggage carts swerved at the last second and collided with the airplane. The second Southwest employee reported that he was standing by the belt-loader with his back to the airplane when he heard someone scream, "Lookout!!" He turned around just as the carts impacted the airplane. He reported that the carts impacted the airplane so hard the rear carts spun around. The police report went on to report that security video recordings were obtainedand showed that in the areas of Gates B-13 and B-15, the Delta Employee could be seen driving the tug out of his traffic lane veering to his left into the south bound traffic lane. The Employee reported that, that was done to avoid an airplane taxiing away from Gate B-15. The report continued that, while traveling north in the southbound lane, the Delta Employee drove over a drain cover east of Gate B-15. When the baggage carts passed over the drain cover, the second baggage cart disconnected from the first baggage cart. According to a Delta representative, after being notified of the event, Delta inspected the tug and baggage carts involved. They reported that all connection parts (tongues and springs) were found to be in good condition. Delta also reported that an additional video showed the tug maneuvering in a gate area for an extended period of time with the same carts attached. Delta reported that the tug driver stated he was confident the carts were properly connected. Previous Events During the airlines' investigations, employees at both Southwest and Delta reported knowing about the dip in the driving lane at the drain cover near Gate B15. Employees stated other similar disconnection events had occurred, but since the events did not result in damage or injury, documentation could not be located or did not exist. The Southwest station manager reported that in November of 2013 an event occurred at the same spot in which a baggage cart disconnected from a tug. He stated the event was brought to the attention of airport authorities who stated the surface could not be leveled at that time because of the winter weather. The Station Manager further stated no action has been taken by the airport since that time. ## Aircraft - Registration: [N758SW](https://openairdocs.org/deregistered/N758SW-2024-11-07), registration cancelled 2024-11-07, S/N 27873, built 1999 (OpenAirDocs) - Reported make and model: BOEING 737 7H4 (7H4) - Registry model: [Boeing 737-7H4](https://openairdocs.org/model/boeing-737-7h4) (registry code 1384404) (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: 27873 - Year built: 1999 - Airframe hours: 53349 - Engines: CFM INTL. CFM56 SERIES 24200 lbs thrust turbo fan; CFM INTL. CFM56 SERIES 24200 lbs thrust turbo fan - Damage: Substantial damage - Flight: Part 121 - Operator: Southwest Airlines Co - Registered owner: Southwest Airlines Co - Airworthiness certificate: Standard, Transport; Standard, Normal - Last inspection: Condition, August 6, 2014 - Airport: SLC, Salt Lake City Intl - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 1, without waivers/limitations; seat: left; restraint: 4-point; flight hours: 15,500 total, 9,500 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 140° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 72 °F, dew point 59 °F - Altimeter: 30.07 inHg ## Docket (4 files) The files NTSB released with the investigation on April 4, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=89880. 5.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40461696&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Delta Cart Inspection (item 2, .PDF, 13 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40461697&FileExtension=.PDF&FileName=Delta%20Cart%20Inspection-Master.PDF - Salt Lake City PD Report (item 3, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40461698&FileExtension=.PDF&FileName=Salt%20Lake%20City%20PD%20Report-Master.PDF - Photos (Courtesy of Southwest Airlines) (item 4, .PDF, 3 photos, 308 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40461699&FileExtension=.PDF&FileName=Photos%20(Courtesy%20of%20Southwest%20Airlines)-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.