# NTSB WPR09IA033: Boeing 737-700, N254WN, Salt Lake City, UT, November 7, 2008 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: November 7, 2008, 16:15 local (23:15 UTC) - Place: Salt Lake City, UT - Coordinates: 40.788333, -111.977775 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.7883&lon=-111.9778&mi=10 - Phase of flight: [Pushback/towing](https://openairdocs.org/ntsb-phases/200) (OpenAirDocs' grouping) - Defining event: [Pushback/towing: Ground collision](https://openairdocs.org/ntsb-events/200) - Highest injury: No injuries - Injuries: 51 uninjured - Status: Completed, report May 12, 2009 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 69419 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR09IA033 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/69419/pdf - Page: https://openairdocs.org/ntsb/WPR09IA033 ## Probable cause The tug driver's failure to maintain situational awareness during the push back operation. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Attention/monitoring: task monitoring/vigilance](https://openairdocs.org/ntsb-findings/02021520): Personnel issues › Psychological · Ground crew (probable cause) - [Perception/orientation/illusion: situational awareness](https://openairdocs.org/ntsb-findings/02022035): Personnel issues › Psychological · Ground crew (probable cause) ## Analysis During a push back from a jetway, the airplane's winglet collided with the winglet of an unoccupied airplane parked at the adjacent gate. Prior to the push back, the wheels of the tug were not aligned straight ahead, but were instead turned partially to one side. Therefore as the push back was initiated, the nose of the airplane moved toward the jetway instead of going straight back. At that point, instead of terminating the push back and realigning the tug, the tug driver attempted to maneuver the tug in a manner that would result in the nose of the airplane clearing the jetway. During this attempt, the tug driver's attention became focused upon the jetway, and he therefore did not see or hear the visual and oral warning signals being given by the wing-walker. ## Factual narrative On November 7, 2008, about 1615 mountain standard time, the wing of a Southwest Airlines Boeing 737-700, N254WN, Flight #784, made contact with the wing of another Southwest Airlines Boeing 737 during the push-back from the jetway at Salt Lake City International Airport, Salt Lake City, Utah. There were no injuries to the two-person flight crew, the three flight attendants, or the 46 passengers. The contact between the two airplanes resulted in the replacement of the right winglet of N254WN. The intended destination of the 14 CFR Part 121 scheduled passenger flight was Los Angeles, California. The incident occurred while the airport was operating under visual meteorological conditions. According to the operator, flight #784 was being pushed back from the jetway of gate B-13 when the airplane's right winglet collided with the left winglet of an unoccupied airplane parked at gate B-15. Reportedly, the wing-walker watching the right wing of flight #784 saw that there was going to be contact, and began yelling at the tug driver to stop. In addition to his oral command, the wing-walker also gave the standard visual stop signal of crossing his two batons, but the tug driver did not see or hear either signal. According to the tug driver, prior to the initiation of the pushback, the wheels of the tug were not aligned straight ahead, but were instead turned partially to one side. Therefore as he began the pushback, the nose of the airplane moved toward the jetway instead of going straight back. At that point, instead of terminating the pushback and realigning the tug, the tug driver attempted to maneuver the tug in a manner that would result in the nose of the airplane clearing the jetway. During this attempt, the tug driver's attention became focused upon the jetway, and he therefore did not see or hear the signals given by the wing-walker. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Pushback/towing: Ground collision](https://openairdocs.org/ntsb-events/200) (defining event) ## Aircraft - Registration: [N254WN](https://openairdocs.org/aircraft/N254WN), registered now, S/N 32512, built 2006 (OpenAirDocs) - Reported make and model: BOEING 737-700 - Registry model: [Boeing 737-7H4](https://openairdocs.org/model/boeing-737-7h4) (registry code 1384404) (OpenAirDocs) - Registry engine: [CFM International CFM56-7B24 series](https://openairdocs.org/engine/cfm-international-cfm56-7b24-series) (registry code 13044, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 32512 - Airframe hours: 8595 - Engines: CFM International CFM56 turbo fan; CFM International CFM56 turbo fan - Damage: Minor damage - Flight: Part 121 - Operator: Southwest Airlines Co - Registered owner: Southwest Airlines Co - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, August 14, 2008 - Departed: KSLC, Salt Lake City, UT - Destination: KLAX, Los Angeles, CA - Flight plan: IFR - Airport: KSLC, Salt Lake City Int. ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 43; injuries: none; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review July 12, 2008; seat: left; flight hours: 10,074 total, 8,400 in this make and model, 4,000 as pilot in command, 160 in the last 90 days, 39 in the last 30 days, 6 in the last 24 hours - Co-pilot; age 43; injuries: none; flight instructor, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review October 1, 2008; seat: right; flight hours: 16,800 total, 2,250 in this make and model, 11,000 as pilot in command, 215 in the last 90 days, 90 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 110° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: 4,100 ft broken - Temperature: 48 °F - Altimeter: 30.38 inHg ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20081107850709I](https://openairdocs.org/incident/20081107850709I), Nov 7, 2008: Boeing 7377H4, Salt Lake City, UT, Minor damage. (-23) N254WN was issue a push back clearance at gate B13 with the intention of flight. While pushing out, the tug operator diverted his attention to the jet… ## Other investigations on N254WN (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB DCA22LA001](https://openairdocs.org/ntsb/DCA22LA001), Jul 5, 2020: Boeing 737-7H4 (N254WN), Orlando, FL, no damage. Probable cause: An encounter with moderate turbulence during descent. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; 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.