Investigation Summary
Approximately 25 minutes after departing Nashville, while cruising at FL350, the aircraft suffered a sudden structural failure in the fuselage crown skin just forward of the vertical stabilizer. The resulting hole caused an immediate loss of cabin pressure, triggering the automatic deployment of passenger oxygen masks and a cabin altitude warning in the cockpit. The captain disengaged the autopilot and initiated an emergency descent to 9,000 feet, where the air was dense enough to sustain the occupants without supplemental oxygen. Post-flight inspection revealed a three-sided flap of skin had peeled back. The NTSB determined that the failure originated from multiple fatigue cracks along a 'chemically milled step,' a manufacturing feature where the thickness of the aluminum skin changes. At the time of the incident, the aircraft had accumulated 50,888 airframe hours. This specific area had not been subject to previous mandatory inspections because finite element modeling by the manufacturer had not previously flagged it as a high-stress zone, despite the stiffness differential at the boundary of the milled and non-milled sections.
Final Conclusions
The National Transportation Safety Board determined the probable cause was fuselage skin failure due to preexisting fatigue at a chemically milled step. The investigation found that fatigue cracks initiated on the inner surface of the skin and propagated outward until the skin could no longer withstand the pressure differential. The NTSB adopted the final report on August 18, 2010.
Video Analysis
The Punctured Plane Luckily Landed Successfully | Southwest 2294 — A detailed look at the structural failure and rapid decompression of Southwest Airlines Flight 2294 and the subsequent emergency landing in West Virginia.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
Held ATP certificate and Class 1 medical.
First Officer
Held ATP certificate and Class 2 medical.
Systems & Failure Modes
Fuselage Skin Assembly
Constructed of two 0.036-inch-thick 2024-T3 aluminum sheets bonded together, with pockets chemically milled away to create a waffle pattern for weight reduction.
Cabin Pressure Control System
Maintains a safe atmospheric pressure inside the aircraft; the failure of the fuselage skin exceeded the system's ability to compensate, leading to rapid decompression.
Interesting Facts
- 01The fuselage rupture measured approximately 17.4 inches longitudinally and between 8.6 to 11.5 inches circumferentially.
- 02The failure occurred at a non-chemically milled bay intended for a potential emergency locator transponder (ELT) antenna installation.
- 03The aircraft had completed 42,500 cycles and 50,888 airframe hours at the time of the incident.
- 04No injuries were reported among the 126 passengers and 5 crew members.
- 05A similar fatigue-related decompression occurred on Southwest Flight 812 less than two years later in April 2011.
Safety Actions & Advisories
Boeing Service Bulletin 737-53A1301
Issued on September 3, 2009, calling for repetitive external inspections to detect cracks in the fuselage skin along the chemically milled step at specific stringers and body stations.
FAA Airworthiness Directive 2010-01-09
Issued on January 12, 2010, mandating the inspection requirements outlined in Boeing's Service Bulletin for 737 Classic aircraft.
Known Controversies & Unanswered Questions
Maintenance and Inspection Oversight
Reference ↗Following the incident, critics pointed to Southwest Airlines' history of maintenance issues, including a $7.5 million fine in 2008 for failing to perform mandatory fuselage inspections on other aircraft. While the specific area that failed on Flight 2294 was not yet subject to mandatory inspections, the event renewed scrutiny of the airline's safety culture and the FAA's oversight.