Southwest grounds 80 airplanes, cancels flights after fuselage rupture

PHOENIX -- Flight attendants had just begun to take drink orders when an explosion rocked the cabin.

Aboard Southwest Flight 812, Shawna Malvini Redden covered her ears, then felt a brisk wind rush by. Oxygen masks fell, the cabin lost pressure, and Redden, suddenly lightheaded, fumbled to maneuver the mask in place.

Then she prayed. And, instinctively, she reached out to the stranger seated next to her in Row 8 as the pilot of the damaged aircraft began a rapid descent from about 34,400 feet.

"I don't know this dude, but I was like, 'I'm going to just hold your hand,' " Redden, a 28-year-old doctoral student at Arizona State University, recalled Saturday.

On Friday, her Phoenix-to-Sacramento flight was forced into an emergency landing at a military base in Yuma with a hole a few feet long in the roof of the passenger cabin. No serious injuries were reported among the 118 people aboard, Southwest officials said.

What caused part of the fuselage to rupture on the 15-year-old Boeing 737-300 was a mystery, and investigators from the National Transportation Safety Board arrived in Yuma on Saturday morning to begin an inquiry.

NTSB board member Robert Sumwalt said investigators will cut a piece out of the fuselage, which would be studied for fracture patterns. Data from the plane's flight recorders and black boxes also will be examined, he said.

Southwest grounded about 80 similar planes for inspection and said around 300 flights were canceled because of the reduced fleet. Spokeswoman Linda Ruther­ford said it was too soon to estimate the cost of grounding part of its fleet.

Flights canceled at McCarran

At McCarran International Airport in Las Vegas, many Southwest flights were delayed, and several were canceled as of Saturday afternoon. McCarran spokeswoman Elaine Sanchez said travelers should monitor their flight's status for the most updated information.

Southwest operates about 170 Boeing 737-300s in its fleet of around 540 planes, but it replaced the aluminum skin on many of the 300s in recent years, Rutherford said. The planes that were grounded Saturday have not had their skin replaced, she said.

"Obviously we're dealing with a skin issue, and we believe that these 80 airplanes are covered by a set of (federal safety rules) that make them candidates to do this additional inspection that Boeing is devising for us," Rutherford said.

Julie O'Donnell, an aviation safety spokeswoman for Seattle-based Boeing Commercial Airplanes, confirmed "a hole in the fuselage and a de­pressurization event" in the latest incident but declined to speculate on what caused it.

A total of 288 Boeing 737-300s operate in the U.S. fleet, and 931 operate worldwide, according to the Federal Aviation Administration.

"The FAA is working closely with the NTSB, Southwest Airlines and Boeing to determine what actions may be necessary," the FAA said in a statement.

Southwest officials said the Arizona plane had undergone all inspections required by the FAA. They said the plane was given a routine inspection Tuesday and underwent its last heavy check, a more costly and extensive overhaul, in March 2010.

An Associated Press review of FAA records of maintenance problems for the plane shows that in March 2010, at least eight instances were found of cracking in the aircraft frame, which is part of the fuselage. Those cracks were repaired, the records indicate. It is not uncommon for fuselage cracks to be found during inspections of planes that age, especially during heavy maintenance checks in which they are taken apart so that inspectors can see areas not normally visible.

The 737-300 is the oldest plane in Southwest's fleet, and the company is retiring 300s as it take deliveries of new models. But the process of replacing all the 300s could take years.

'People were dropping'

Seated one row from the rupture, Don Nelson said it took about four noisy minutes for the plane to dip to less than 10,000 feet.

"You could tell there was an oxygen deficiency," he said.

"People were dropping," said Christine Ziegler, a 44-year-old project manager from Sacramento who watched as a crew member and a passenger fainted.

Brenda Reese said the hole was "at the top of the plane, right up above where you store your luggage."

"The panel's not completely off," she said. "It's like ripped down, but you can see completely outside. ... When you look up through the panel, you can see the sky."

Cell phone photos provided by Reese show a panel hanging open in a section above the plane's middle aisle.

At an altitude of more than 34,000 feet, the Southwest pilots would have had only 10 to 20 seconds of "useful consciousness" to get their oxygen masks on or pass out, said John Gadzinski, an airline pilot and aviation safety consultant.

"The higher you are, the less useful consciousness time you have," said Gadzinski, president of Four Winds Consulting in Virginia Beach, Va. "It's a credit to the pilots that they responded so quickly."

A loss of cabin pressure just after takeoff knocked out the pilots of a Helios Airways Boeing 737 in August 2005. The plane flew into a hillside north of Athens, Greece, killing all 121 people aboard. An investigation found the pilots had failed to heed a warning that the pressurization system wasn't working correctly.

Aerodynamics not affected

In the Southwest case, the hole and subsequent depressurization wouldn't have affected the pilots' ability to control the plane as long as they had their oxygen masks on, Gadzinski said.

"The fact that you have a breach hole doesn't affect the aerodynamics of the plane. The plane still flies exactly the same," he said.

A similar incident happened in July 2009 when a football-sized hole opened in flight in the fuselage of another Southwest 737, depressurizing the cabin. The plane made an emergency landing in Charleston, W.Va. It was later determined that the hole was caused by metal fatigue.

In response to that incident, Southwest changed its maintenance plan to include additional inspections, which the FAA reviewed and accepted, said John Goglia, a former NTSB member and an expert on airline maintenance.

The latest incident "certainly makes me think there is something wrong with the maintenance system at Southwest, and it makes me think there is something wrong with the (FAA) principal maintenance inspector down there that after that big event they weren't watching this more closely," he said.

There was "never any danger that the plane would fall out of the sky," Goglia said. "However, anybody on that airplane with any sort of respiratory problems certainly was at risk."

In 1988, cracks caused part of the roof of an Aloha Airlines Boeing 737 to peel open while the jet flew from Hilo to Honolulu. A flight attendant was sucked out of the plane and plunged to her death, and dozens of passengers were injured.

Las Vegas Review-Journal reporter Mike Blasky contributed to this report.