Just eight weeks ago, three major U.S. airlines announced they were voluntarily grounding some of their planes to perform routine maintenance out of what they claimed was "an abundance of caution."
More from TODAY.com
Conspiracy theories grow around MH17
NBC’s Keir Simmons drove to an area near the Russian border, where it’s claimed a missile launcher was seen last week. Wes...
- Toast your selfie! New toaster lets you admire yourself while you eat
- Jenna Bush Hager: 5 things I've learned from my Gampy
- George H.W. Bush talks to TODAY about turning 90
- Why 7 hours of sleep a night may be better than 8
- Conspiracy theories grow around MH17
American Airlines and Delta grounded their MD-80s, and United grounded its entire fleet of Boeing 777s. The result: Canceled flights and thousands of stranded passengers nationwide.
So what really happened? It began when Southwest failed to properly inspect nearly 50 737s. FAA whistleblowers delivered testimony before Congress — and the FAA launched audits to determine if airlines were complying with safety rules.
The FAA acknowledges the Southwest breach, but calls it an "isolated incident."
"That was a failure on our part — as well as a failure of all the airlines," says Acting FAA Administrator Robert Sturgell. "But we've learned from that. We're gonna make some changes that'll prevent those kinds of things from happening again."
But it happened once before. Twenty years ago, the FAA ordered mandatory inspections when an Aloha Airlines 737 nearly ripped apart after a single crack spread through its hull and tore the plane's top off.
It all gets down to who is inspecting the planes — and how often.
Aviation expert Michael Barr contends that the FAA needs more inspectors, and that they need to be on maintenance sites "getting their hands dirty."
"I'd like to see them get more funding," he says, "and with that extra funding, we're going to get more inspectors. And then we can get away from the assumption that the airlines are going to tell us everything within the airlines."
But just how difficult is maintaining the aging U.S. fleets?
In the last few months, five U.S. airlines have either ceased to operate or have filed for bankruptcy protection, victims of soaring fuel prices and a tough economy.
Many airlines can't afford the costs of maintaining older planes, and some of them are brought to a 200-acre windswept airplane boneyard in California's Mojave Desert, which I recently visited. Dozens and dozens of DC-9s, 767s, DC-10s, an assortment of 747s and other aircraft either stripped or mothballed, sitting in the dry desert heat.
But what about the other planes still flying? It's because of rising costs that many airlines, like USAir and JetBlue, are sending their planes overseas for maintenance — at a fraction of the costs the work would run the airlines if they opted to perform that maintenance in the U.S.
And it begs the question: Who's inspecting the work?
Aeroman is a repair facility in El Salvador that works on those planes. Other foreign repair operations are in China, Korea, Dubai and Singapore.
The FAA claims it doesn't have a problem with this outsourcing. "We've got about 700 foreign repair stations right now," says the FAA's Sturgell. "That's compared to 4,000 located in the United States. So we not only send our inspectors at least once a year to these facilities, but the process is that you also have the air carriers, who ultimately are responsible for the work that is done."
But that trend worries experts like international air safety consultant Greg Feith, a former National Transportation Safety Board lead investigator.
"What's really happening is that the airlines are inspecting the work that's done on their particular aircraft by an outside vendor. Whether that inspection is very encompassing or not is another question, because unlike here in the United States, where you may have seven or eight or 10 inspectors in an in-house airline facility, they only have one or two at that facility overseas. They can't do a total inspection on a 747 with two people."
Not a particularly comforting thought. Still, the FAA stands by its staffing levels: "We think where we are today is right for the system as a whole," argues Sturgell. "As the work changes, as the type of work gets more complicated, as more of it is performed, then we'll adjust our staffing. But we certainly don't certify more foreign repair stations than we can handle as an inspector work force."
Congressman Jim Oberstar — who chaired those congressional hearings on Southwest and the FAA — acknowledges that many of the overseas operations are, in fact, solid — but he is working to pass legislation to mandate more inspectors to assess the work.
"It's really quite clear," he says, "and it’s right in the charter of the FAA. 'Safety and aviation shall be maintained at the highest possible level.' Airlines choose the level they can afford, not what they want. That's the standard. But," he adds, "we're not there. We need to do better."
The real bottom line — regardless of where the maintenance is performed — is who is inspecting the work, how often they're inspecting the work, and perhaps most important, how they're inspecting the work. All too often, inspectors are not, as Mike Barr suggests, "getting their hands dirty." They're not inspecting the physical maintenance work on aircraft.
Instead, they're inspecting the paperwork that says the required maintenance was performed.
And, after all, anyone can simply check off a box on a piece of paper.
"The FAA is so shorthanded," says Oberstar, "our problem is we're inspecting paperwork, not engine work. One of the witnesses at our hearing said, 'Well, Mr. Chairman, it was just a small crack. It was just a tiny, tiny crack. And I said, 'Yes, it was just a tiny crack on that Aloha Airlines 737 that spread to an 18-foot section of the hull. It was just a tiny crack in the engine of a United Airlines DC-10 bound for Chicago that caused 110 people to perish in Iowa.' "
Peter Greenberg is TODAY’s travel editor. His column appears weekly on TODAYshow.com. Visit his Web site at PeterGreenberg.com.
© 2013 NBCNews.com Reprints