NATION : U.S. Tightens Sky Terrorism Curbs

<i> From Times wire services </i>

The Transportation Department today announced new measures to combat sky terrorism after a meeting with President Bush by relatives of Americans killed in the bombing of Pan Am Flight 103 over Scotland.

Transportation Secretary Samuel K. Skinner told a news conference that airlines will be required to acknowledge all Federal Aviation Administration security bulletins within 24 hours, and compliance with them would be mandatory.

Such bulletins tell airlines of possible threats and recommend steps that can be taken to avert them. In the past, such recommendations generally have been advisory. Skinner also said airlines will be required to install equipment to detect plastic explosives in all high-risk airports throughout the world. (Bush visit story on Page 2.)