WPR09IA033

NTSB incident investigation · Boeing 737-700 · Salt Lake City, UT · November 7, 2008

Incident · No injuriesIncident investigationFinal report
Date
November 7, 2008, 16:15 local (23:15 UTC)
Place
Salt Lake City, UT
Injuries
51 uninjured
Damage
Minor damage
Phase of flight
Pushback/towing
Aircraft
N254WNBoeing 737-700
Defining event
Pushback/towing: Ground collision
Weather
Visual (VMC) · Day
Status
Completed · report May 12, 2009
Report
Approved by Office Director
NTSB office
Western Pacific Region
Parties
Federal Aviation Administration
FAA report
20081107850709I
Case key
69419

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the incident.

On this page

Probable cause

The NTSB’s determination of the probable cause, and any contributing factors.

The tug driver's failure to maintain situational awareness during the push back operation.

Findings · 2

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings.

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 is the one that best describes the accident.

Aircraft

Registration
N254WN
Reported as
Boeing 737-700
Category
Airplane
Serial number
32512
Airframe hours
8,595
Engines
CFM International CFM56, turbo fanCFM 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.

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew · 2

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
43
Injuries
None
Certificate
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
Role
Co-pilot
Age
43
Injuries
None
Certificates
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.

Other investigations on N254WN · 1

Matched to the same aircraft by N-number and date.