Boeing 737-823 N909NN and Boeing 737-7H4 N963WN accident near Chicago, Illinois

Probable cause

Southwest Airlines flight crew’s misjudgment of the distance required to safely pass the American Airlines airplane.

NTSB analysis

After landing on runway 27R at Chicago O’Hare International Airport, Southwest Airlines B737 flight 2659 (SWA2659) was cleared by ground control to taxi to gate M-14 via taxiways Z, D, TT, A, A-19. As they proceeded down taxiway A, both pilots observed an American Airlines B737 (AA1121) holding short of taxiway A-19. The pilots of SWA2659 asked ground control for permission to utilize taxiway A-20 instead and were granted permission. The captain said that as he tried to pass AA1121, he stayed left of centerline to ensure wingtip clearance. The first officer was looking out the window and informed the captain that their airplane’s wingtip was clear. However, their right winglet impacted the left elevator of AA1121. AA1121 was stationary on taxiway A and holding short of taxiway A-19 with the parking brake set, awaiting entry to gate K-20, when it was impacted by SWA2659.

Figure 1. Depiction of SWA2659 taxi route and area of occurrence (Adapted from Google Earth)

Post-event examination of both airplanes revealed that the right winglet of SWA2659 was damaged and sheared off by the impact and the left elevator of AA1121 was substantially damaged.

Text from the NTSB. Open the NTSB docket for DCA22LA201 for the full record.