An antiquated warning system for the nation's pilots has led dozens of them to receive unreliable information about slippery runways and to land in dangerous conditions, according to a USA TODAY review of accidents and pilot reports during the past decade.

In at least 42 cases since 1995, pilots of commercial and corporate aircraft reported skidding off runways after receiving reports that the runways were safe, according to NASA's Aviation Safety Reporting System.

The reports shed light on the weaknesses of a warning system in which pilots rely on other pilots who have landed recently on slick runways to report conditions on a scale that ranks braking from "good" to "nil." The reports, relayed by air traffic controllers, are subjective, and the braking abilities of different types of planes vary.

Icy conditions came into play in last month's crash of a Southwest Airlines jet, which skidded off a snowy runway at Chicago's Midway Airport and onto a nearby road. The jet struck a passing car, killing a 6-year-old boy.

Among the issues being investigated are the condition of the runway and the information passed to pilots by controllers, says Keith Holloway, a spokesman for the National Transportation Safety Board.

Pilots and investigators have long complained that pilots aren't given enough information about slippery runways, accident records show. It "can be a life-and-death matter," says Bernard Loeb, ex-chief of the NTSB's aviation division.