'We Lost the Cabin'

Article excerpt

Byline: Clive Irving

At 10:56 p.m. on April 1 last year, Southwest Airlines Flight 812, en route from Phoenix to Sacramento with 118 passengers aboard, was completing its climb to its cruise altitude of 36,000 feet. An air-traffic controller at Los Angeles Center had just acknowledged a routine call from the pilot. But within a minute or so the controller became aware that Flight 812 was in some kind of trouble. The messages were garbled until, finally, he heard the pilot clearly: "...declaring an emergency we lost the cabin."

Shawna Malvini Redden, a 29-year-old doctoral student at Arizona State, had just settled into a window seat in row 8 when there was an ear-splitting bang. Oxygen masks dropped from the ceiling and the airplane pitched forward.

The Los Angeles controller asked the pilot to repeat the message. "Request an emergency descent we've lost the cabin and we're starting down."

"We lost the cabin" meant that the airplane had suffered a sudden and extreme loss of cabin pressure. The pilots had two urgent priorities--to get to a lower altitude and to find an airport for an emergency landing.

As a blast of air rushed through the cabin, Malvini Redden felt reassured by the flight attendants' composure. But she reached over to the man in the aisle seat and took his hand. "If I'm going to go down," she thought, "at least I want to feel connected to somebody."

Flight 812 touched down safely a few minutes later in Yuma, Ariz., a hole 59 inches long and nine inches wide in the roof of the cabin. The skin of the airplane had peeled away. To inspectors from the National Transportation Safety Board, the structural failure must have seemed worryingly familiar: there had been a similar episode involving another Southwest airplane in July 2009; additionally, the airplane type involved, the Boeing 737, had a history of weaknesses in its fuselage skin. When the NTSB took the damaged part of the cabin roof from Flight 812 back to its labs in Washington, they found serious manufacturing flaws. Forty-two rivet holes at joints where the fuselage skin overlapped, called lap joints, were so far out of alignment that the lower holes had become oval, not round, causing fatigue cracks, and paint had leaked from the outer skin into the joints.

This specific plane had been delivered in 1996, a version of the 737 known as the Classics. Immediately after the Flight 812 emergency, Boeing's chief engineer for the series, Paul Richter, said that Boeing had anticipated some level of cracking in the relevant area, but not so soon in the plane's life cycle. And the CEO of Boeing Commercial Airplanes, W. James McNerney, asserted that the problem was poor manufacturing of one airplane, not a broader design issue.

The 737 Classics were supposed to have a safe service life of 60,000 flights. In fact, to meet that standard, they must be judged to be capable of flying twice that number. But the Southwest 737 had accumulated 39,781 cycles, a number so alarmingly below the bar set for safety that it has thrown into question the entire safety regime.

"You look at something like that and you say, 'Wow! This is not just a Monday-morning mistake on a production line. There is something deeper here,'?" said Gene Doub, a former air-crash investigator for the NTSB, about the kind of failure the board had found in the case of Flight 812. Pat Duggins, a member of the Aviation Safety Institute with 28 years of experience in the industry, agreed. He told me: "It is impossible for this to have happened on just one airplane, it's not a flash in the pan. The production regime and the maintenance-checking regimes are failing."

Was there, in fact, an endemic problem with the 737's fuselage? Boeing, in a written response to issues raised during this investigation, insists that the "continued safety record and commercial success of the 737 demonstrates that Boeing over time has incorporated many enhancements and technical advances into the airplane's systems and structure. …