The government has been trying for years, with one spectacular failure along the way, to develop systems to retard aircraft fires such as the one that swept a Northwest Airlines jetliner this week.

The hope at one time was that an anti-misting fuel additive would prevent the vapors in jet fuel from igniting and exploding in a crash.In on-the-ground stationary tests the additive appeared to work, and the Federal Aviation Administration was close to requiring airlines to add it to jet fuel.

But when the FAA deliberately crashed a remote-controlled Boeing 720 in the California desert six years ago to test the idea under realistic conditions, the jetliner exploded in flames.

Eleven months later, the FAA acknowledged: "The concept is not practical for day-to-day airline operation in the foreseeable future."

The experiment was not repeated, and as Monday's runway collision at Detroit's Metropolitan Airport shows, fire remains a constant hazard in aviation accidents.

In the years since the failure of the fuel-additive experiment in 1984, the FAA and the Department of Transportation have concentrated on trying to make the immediate surroundings of air passengers more flame-resistant.