Pilot Debrief

BOEING 737 7H4 near Chicago, IL — 2017-10-02

Final reportDCA18CA001
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Date
2017-10-02
Location
Chicago, IL, USA
Airport
KMDW
Aircraft
BOEING 737 7H4
Registration
N930WN
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Ground

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.

NTSB 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.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Ramp agent could have turned off ignition or used manual shut down lever.

NTSB coding

Evidence available

  • Photos
  • 2 docket documents
View NTSB final reportView NTSB docket

Docket documents2

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