# NTSB DCA18CA001: Boeing 737 7H4, N930WN, Chicago, IL, October 2, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: October 2, 2017, 08:40 local (13:40 UTC) - Place: Chicago, IL - Coordinates: 41.786388, -87.745277 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.7864&lon=-87.7453&mi=10 - Phase of flight: [Prior to flight](https://openairdocs.org/ntsb-phases/100) (OpenAirDocs' grouping) - Defining event: [Prior to flight: Ground handling event](https://openairdocs.org/ntsb-events/080) - Highest injury: No injuries - Injuries: 84 uninjured - Status: Completed, report June 8, 2020 - Report: Approved by Office Director - NTSB office: Major Investigations Division - NTSB case key (mKey): 96133 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA18CA001 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/96133/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=96133 - Page: https://openairdocs.org/ntsb/DCA18CA001 ## Probable cause the mechanical failure of the tugs fuel governor, which made it difficult for the ramp agent to stop the tug. Contributing to the accident was the lack of guidance on how ground personnel were to handle vehicle malfunctions. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Loading](https://openairdocs.org/ntsb-findings/01011500): Aircraft › Aircraft handling/service · Not serviced/maintained (probable cause); cases with it: [Boeing 737-7H4, 1 case](https://openairdocs.org/ntsb-findings/01011500/cases.md?model=1384404), [All aircraft, 35 cases](https://openairdocs.org/ntsb-findings/01011500/cases.md) - [Training: initial training](https://openairdocs.org/ntsb-findings/04031010): Organizational issues › Support/oversight/monitoring · Training organization (probable cause); cases with it: [Boeing 737-7H4, 1 case](https://openairdocs.org/ntsb-findings/04031010/cases.md?model=1384404), [All aircraft, 15 cases](https://openairdocs.org/ntsb-findings/04031010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: 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 On October 2, 2017, at about 0840 CDT, Southwest Airlines flight 681, Boeing B737-700, N930WN, was struck by an unmanned tug while boarding was ongoing at Chicago Midway Airport (KMDW), Chicago, Illinois. There were no injuries to the 84 passengers and crew onboard. The airplane received substantial damage to the lower fuselage skin, frames and stringers over an area about 3 feet by 3 feet. The flight was operating under 14 Code of Federal Regulation Part 121 as a scheduled passenger flight from KMDW to Omaha Airport (KOMA), Omaha, Nebraska. A ramp agent was driving a covered baggage tug with two baggage carts in tow between Gates B22 and B24 when the tug made contact with two staged baggage carts. The ramp agent jumped off the tug as the tug continued to accelerate forward. The now unmanned baggage tug struck additional ground support equipment before striking the fuselage of the accident airplane at Gate B22. The ramp agent stated afterwards that he could not get the tug to stop and thought running the tug into the staged baggage carts would stop or at least slow the tug down. Examination of the baggage tug after the event revealed there was a mechanical failure of the fuel governor which resulted in the runaway. The runaway could have been stopped by either turning the ignition key off or using the manual shut down lever on the front cover. There was no guidance in the Ground Operations Training Manual related to how ramp personnel should handle mechanical failures of ground support equipment. ## Factual narrative On October 2, 2017, at about 0840 CDT, Southwest Airlines flight 681, Boeing B737-700, N930WN, was struck by an unmanned tug while boarding was ongoing at Chicago Midway Airport (KMDW), Chicago, Illinois. There were no injuries to the 84 passengers and crew onboard. The airplane received substantial damage to the lower fuselage skin, frames and stringers over an area about 3 feet by 3 feet. The flight was operating under 14 Code of Federal Regulation Part 121 as a scheduled passenger flight from KMDW to Omaha Airport (KOMA), Omaha, Nebraska. A ramp agent was driving a covered baggage tug with two baggage carts in tow between Gates B22 and B24 when the tug made contact with two staged baggage carts. The ramp agent jumped off the tug as the tug continued to accelerate forward. The now unmanned baggage tug struck additional ground support equipment before striking the fuselage of the accident airplane at Gate B22. The ramp agent stated afterwards that he could not get the tug to stop and thought running the tug into the staged baggage carts would stop or at least slow the tug down. Examination of the baggage tug after the event revealed there was a mechanical failure of the fuel governor which resulted in the runaway. The runaway could have been stopped by either turning the ignition key off or using the manual shut down lever on the front cover. There was no guidance in the Ground Operations Training Manual related to how ramp personnel should handle mechanical failures of ground support equipment. ## Aircraft - Registration: [N930WN](https://openairdocs.org/aircraft/N930WN), registered now, S/N 36636, built 2009 (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 CFM56-7B24/3 series](https://openairdocs.org/engine/cfm-international-cfm56-7b24-3-series) (registry code 13074, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 36636 - Year built: 2009 - Airframe hours: 30104 - Engines: CFM International CFM56-7B24 turbo fan; CFM International CFM56-7B24 turbo fan - Damage: Substantial damage - Flight: Part 121 - Operator: Southwest Airlines - Registered owner: Wells Fargo Bank Northwest Na Trustee - Airworthiness certificate: Standard, Transport - Last inspection: September 27, 2017 - Departed: KMDW, Chicago, IL - Destination: KOMA, Omaha, NE - Flight plan: IFR - Airport: KMDW, Chicago Midway International A - Equipment: Electronic primary flight display, Electronic multifunction display, Electronic flight bag or handheld device, Data recorder, Heads up display, Onboard weather, Stall warning system ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: 7,000 ft broken - Temperature: 68 °F, dew point 52 °F - Altimeter: 30.19 inHg - Observed at: KMDW ## 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 20171002014309A](https://openairdocs.org/incident/20171002014309A), Oct 2, 2017: Boeing 737-7H4, Chicago, IL, Substantial damage. Aircraft N930WN was parked at gate B22 at Midway (mdw) airport and actively loading passengers when it was struck by a baggage cart tug. The area on the… ## Docket (2 files) The files NTSB released with the investigation on July 14, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=96133. 10.9 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 600 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40485358&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Photos (item 2, .PDF, 10 photos, 10.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40485359&FileExtension=.PDF&FileName=Photos-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.