FAA launches probe after in-flight incident results in 12-inch crack in older Southwest 737 jet

The FAA is to launch an in-depth investigation after a Southwest Airlines (Southwest) 737, en route to Boise, Idaho from Las Vegas, Nevada, experienced a gradual loss of cabin pressure, during which, over a six-minute period, the pilots began a rapid descent from 36,000 feet down to 22,000 feet, an altitude deemed much safer for passengers. The jet continued its flight to Boise without further incident.

The cabin depressurization was sufficiently slow that at no time were oxygen masks automatically deployed from above the passengers and no injuries were reported. On landing at Boise, the older-model 737 was thoroughly inspected and a 12-crack was discovered in the plane’s crown immediately behind the cockpit. This particular area is scheduled for inspection every 1,500 flights and according to a Southwest spokesperson, the last inspection fell within that flight period. According to the Wall Street Journal, when reporting the incident to the Federal Aviation Authority (FAA), Southwest also confirmed that during routine maintenance checks, the carrier had found external cracks on two other aircraft.

In 2011 a five-foot-long hole ripped opened in another Southwest 737, forcing pilots to make an emergency landing at a military base in Arizona. Investigators blamed fatigue cracks in the plane’s skin. The American carrier’s maintenance record has come under close scrutiny before, with the FAA proposed a US$10.2 million fine in 2008 against Southwest for failing to conduct mandatory inspections for fatigue cracks on a number of its aircraft.

In February of this year, according to US News, the Transportation Department’s inspector general confirmed that Southwest had flown used planes it had purchased without obtaining verification of their maintenance and repair histories. The agency added that, “Many officials throughout the FAA have expressed concern about the safety culture at Southwest Airlines,” though Southwest has denied the allegations.