Transportation Department officials have ordered U.S. airlines to take stricter anti-terrorism measures - clearly a necessity in the wake of the explosion that destroyed a Pan Am aircraft over Lockerbie, Scotland, on Dec. 21, killing all 270 people on board.

Yet grieving relatives of the victims say the requirements aren't strong enough and call the plane's destruction a "preventable massacre."A massacre it certainly was, and while the anguish of the victims' families is understandable, it may be going too far to declare that such terrorist acts are "preventable."

International aviation is vulnerable in dozens of different ways and in hundreds of places. It's folly to believe that every terrorist act, no matter how carefully plotted and carried out, can somehow be prevented.

Even if all luggage were hand searched - which is what the victims' families are demanding until more sophisticated detectors are installed - it would not be foolproof. Every radio, every electric shaver, every other piece of equipment or container, including bars of soap, would have to be dismantled, unwrapped, and otherwise examined.

Exotic equipment can help, but innovative devices of destruction may always be a half-step ahead of technology to detect them. There's no such thing as absolute, total guaranteed safety in airline travel.

However, installing more devices to detect plastic explosives, as the Transportation Department has ordered, is prudent and sensible.

Yet fighting terrorism aimed at airlines ought to be the responsibility of the American government as well as private airlines. Instead of making airlines spend millions for new detection equipment - a process that could take years to fully implement - Washington ought to take a hand.

The Air Transport Association, which represents the airlines, says the FAA could use some of the billions of surplus dollars in the Aviation Trust Fund to buy sophisticated airport detection equipment and help defend against terrorism. That suggestion makes sense.