Bird strike Incident Boeing 737-3H4 (WL) N360SW, 23 Dec 2013
ASN logo
ASN Wikibase Occurrence # 204511
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information. If you feel this information is incomplete or incorrect, you can submit corrected information.

Time:16:15 LT
Type:Silhouette image of generic B733 model; specific model in this crash may look slightly different    
Boeing 737-3H4 (WL)
Owner/operator:Southwest Airlines
Registration: N360SW
MSN: 26571/2307
Fatalities:Fatalities: 0 / Occupants: 115
Other fatalities:0
Aircraft damage: Minor
Location:Saint Louis-Lambert International Airport, MO (STL/KSTL) -   United States of America
Phase: Initial climb
Nature:Passenger - Scheduled
Departure airport:Saint Louis-Lambert International Airport, MO (STL/KSTL)
Destination airport:Kansas City International Airport, MO (MCI/KMCI)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
A Boeing 737-3H4, registration number N360SW, operated by Southwest Airlines as flight 1091, and powered by two CFM56-3 turbofan engines, experienced a bird strike and ingestion on the No. 2 or right-hand engine after takeoff from Saint Louis-Lambert International Airport, Missouri, USA. As the airplane climbed through 1,700 feet, it impacted multiple birds causing damage to the no.2 engine and wing. The pilot declared an emergency and returned to Saint Louis for an uneventful landing. There were no injuries reported to the 110 passengers, 2 flight crew and 3 flight attendants.

Examination of the airplane revealed no damage to the fuselage. Examination of the engine revealed no penetration or breaches of the cases; however, the fan case exhibited several bulges that corresponded to hard impacts and missing fan blade rub strip material exposing the parent material below.
Examination of the no.2 engine revealed that all the fan blades were extensively damaged exhibiting hard-body impact damage with significant material loss along the length of the leading edge. Two adjacent fan blades were fractured transversely across the airfoil near the one-third span, and exhibited leading edge soft-body impact damage. The remains of the two birds were identified as one male and one female mallard duck. The average weight of the male mallard is 1246 grams or 2.75 pounds; the average weight of the female mallard is 1095 grams or 2.4 pounds.

The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
The initial damage to the fan blades was caused by the ingestion of two mallard ducks that caused one or more fan blades to fracture, striking the fan shroud, as well as other passing fan blades, producing various sized blades fragments that created a cascading effect of collateral impact damage to the other fan blades, the fan case, and the inlet cowl. One large blade fragment was deflected out of the fan containment plane, which pierced and exited the inlet cowl in a benign direction.

The engine and airplane met the applicable bird and containment design standards since the engine did not catch on fire, no engine cases exhibited any penetrations, the engine was able to be shutdown normally, and the airplane damage did not impact the safe operation of the airplane or create a hazard to the persons on board.


Accident investigation:
Investigating agency: NTSB
Status: Investigation completed
Duration: 4 years
Download report: Final report


Photo: NTSB

Photo: NTSB

Photo: NTSB

Revision history:

15-Jan-2018 20:53 harro Added
15-Jan-2018 20:55 harro Updated [Photo, ]
15-Jan-2018 20:55 harro Updated [Photo, ]
15-Jan-2018 20:55 harro Updated [Photo, ]

Corrections or additions? ... Edit this accident description

The Aviation Safety Network is an exclusive service provided by:
Quick Links:

CONNECT WITH US: FSF on social media FSF Facebook FSF Twitter FSF Youtube FSF LinkedIn FSF Instagram

©2023 Flight Safety Foundation

1920 Ballenger Av, 4th Fl.
Alexandria, Virginia 22314