From Air Safety Week:

Not necessarily predictors

A favorable trend is not necessarily a reliable predictor of future performance, especially if negative forces are building below the surface optimism. There is a saying to the effect that whenever one thinks a favorable trend is going to continue, that's probably just about the time it is going to reverse. The Airclaims 2003 year-end review showed a favorable trend of declining accidents, culminating on one of the best years ever for 2003 (see ASW Jan. 5). But the underlying theme of the Airclaims assessment is that conclusions should be drawn with care - any celebration of the statistical improvement could be naively premature. From numerous security threats (bombs, missiles, hijackings), and technical deficiencies (blanked-out cockpit instruments for reasons presently unknown), the industry may well be in an era of silent desperation. The environment for fatigue-induced errors, impaired judgment and risk-taking is primed by the present state of play. There are reports that in some quarters that flight time/duty time regulations are viewed as target parameters rather than absolute maximums.

New jets may be more reliable, but they are more complex. Fault isolation and trouble-shooting may be more difficult, a problem compounded by unclear if not inaccurately misleading maintenance manuals. There is less experience on the ramp, the requirement for aircraft and powerplant (A&P) technicians having given way to less-trained and less- experienced contract service providers.

More maintenance is being outsourced. While there are many reputable companies performing maintenance on a contract basis, the training and experience level of their people is often less, and greater turnover may aggravate a proficiency problem. Indeed, the potential for maintenance-related mishaps has prompted Rep. James Oberstar (Mich.), ranking Democratic member of the House Transportation and Infrastructure Committee, to request a Department of Transportation Inspector General (DOT/IG) review of the situation.

So far, most of the reports are anecdotal, but the current environment of economic squeezing seems to be producing chronic pilot fatigue and maintenance shortcutting.