SECURITY MEASURES WILL IMPEDE TRAVELERS, HIKE AIRLINE EXPENSES.

Byline: John H. Cushman Jr. The New York Times

The new aviation security measures imposed Thursday by the Clinton administration will confront passengers between American cities with the kinds of long lines, detailed searches and interrogations that international voyagers are used to, and flights out of the country will be scrutinized even more intensively.

The measures are based on a growing realization that the risks of terrorism within the United States are increasing, and that airlines and airports no longer can view domestic skies as a safe haven or the country's big international airports as immune.

Transportation Secretary Federico Pena said: ``There will be more inspection of bags. There will be more interviews of passengers. There will be delays, there will be inconvenience, there will be longer lines. We're asking people to come prepared with photo ID's and prepared to have their luggage, particularly when it is checked in, to be inspected.''

It is not clear how extensive the delays will be. Some travel experts said that airlines might urge passengers to add an hour to their schedules, showing up for domestic flights two hours before departure and for international flights three hours early. Others said the delays might add no more than 15 minutes to a half hour to normal schedules. Many airports in Europe and the Middle East have imposed strict security measures for more than 10 years.

The industry's concerns are somewhat different. There will be added labor costs and delays while planes are searched, which will result in a loss of income. Several travel experts said Thursday that they expected the added costs of the security measures to be passed along to customers through higher ticket prices or surcharges. That is what happened when new security measures were put in place after the bombing of Pan Am Flight 103 over Lockerbie, Scotland, in 1988.

Senior officials said much of what is being ordered was under consideration even before the TWA disaster occurred, a reflection of deepening intelligence concerns.

The extra screening of passengers and baggage and the tighter controls on unaccompanied luggage, and the disruption of traveling routines the measures will bring, will begin within days, officials said.

At any big airport, some of the carry-on bags that are now put through X-ray machines will be unpacked and inspected by security officers. Not every carry-on bag must be inspected by hand, according to a directive sent to airlines Thursday, but there will be physical searches taking place ``at each X-ray unit at all times,'' the directive said.

On international flights, some passengers and their luggage will be selected for special attention, depending on their nationality and itinerary, among other factors.

Other measures will not be so obvious to passengers, like the intensive searches of airplane cargo holds, one step intended for international flights.

``We will require preflight inspections for any plane flying to, or from, the United States,'' President Clinton said. ``Every plane, every cabin, every cargo hold, every time.''

That means delay and financial losses, as would a decision that the administration is considering: requiring the use of sophisticated new explosive detection equipment in every major airport in the country.

To speed those decisions, Clinton appointed Vice President Al Gore to review airline safety and the pace of modernization. Gore is to report back to Clinton in 45 days.