In December, the National Transportation Safety Board faulted the Federal Aviation Administration for contributing to the January 2000 crash of an Alaska Airlines jet that killed 88. The indictment of the FAA was not the first. In 1997, the safety board held the agency partly responsible for a 1996 crash in which 110 died when a ValuJet plane plummeted into the Florida Everglades.

Now a two-year USA TODAY investigation concludes that the FAA might have played a role in yet another airline disaster — a 1998 crash that claimed 229 lives when a Swissair jumbo jet plunged into the Atlantic Ocean.

FAA faulted The Federal Aviation Administration has been criticized in connection with three crashes in the past seven years: ValuJet: Crashed in the Florida Everglades on May 11, 1996, killing 110. The FAA was faulted for failing to adequately monitor maintenance and outside contractors used by the airline. Swissair: Crashed in the Atlantic Ocean on Sept. 2, 1998, killing 229. USA TODAY found that the FAA failed to thoroughly check out a new entertainment system that may have sparked a deadly electrical fire. Alaska Airlines: Crashed in the Pacific Ocean on Jan. 31, 2000, killing 88. Federal safety officials said the FAA "failed miserably" to oversee the airline's inspection and maintenance programs.

In all three tragedies, the FAA botched its paramount mission: to make sure that those inspecting, maintaining and modifying commercial airliners do their jobs properly.

Such lax monitoring is a growing problem. Increasingly, the FAA is turning to private companies to handle a range of tasks in its stead. Yet it has broken repeated pledges to put better safeguards in place to protect fliers from shoddy work by these firms.

The Swissair crash underscores the risks of further delay. USA TODAY reported last week that the airline had fitted some of its planes with a sophisticated entertainment system that let passengers watch movies, shop and gamble. The FAA failed to oversee the installation, and problems later surfaced with both the system and Santa Barbara Aerospace, the company that signed off on the safety of the planes. Before the crash, the FAA repeatedly cited the firm for poor performance and even briefly suspended it while the entertainment system was being installed on Swissair planes.

Those concerns should have prompted the FAA to take a closer look at the project. But it didn't. Swissair Flight 111 carried a system suspected of sparking a deadly electrical fire, though an official cause has not yet been released. Only after the crash did the FAA acknowledge risks with the system and Santa Barbara Aerospace's procedures.

Such inadequate oversight of a private contractor isn't just a recent problem. In 1993, the General Accounting Office (GAO), the investigative arm of Congress, complained that the FAA wasn't "effectively involved" in overseeing the work performed by outside companies.

In response to the Swissair disaster, the FAA tightened its monitoring procedures. It rewrote guidelines for issuing some safety certificates, for example, and required more intensive oversight of private contractors. Still, the USA TODAY investigation raised disturbing questions about the effectiveness of those changes.

That fits a sorry pattern, too. In the wake of the ValuJet crash, the FAA embarked on a redesign of its inspection program to do a better job of catching mistakes before they cause a fatal accident. But nearly five years after its introduction, that program remains incomplete. In January, the GAO said the FAA hasn't "established strong oversight and accountability procedures."

The FAA says it now keeps in closer contact with contractors. The agency also points to the millions of flights each year that operate safely.

Yet even a rare crash that could have been averted is one too many. The FAA lacks the resources to inspect every plane. But it has an obligation to make sure that those who are handling inspections do a diligent job.