First Published in 1999. The recent conviction of Ramzi Ahmed Yousef for plotting what prosecutors called “48 hours of terror in the sky“ by conspiring to bomb a dozen US airliners, the increasing number of man portable SAM attacks on aircraft, and the recent crash of a hijacked Ethiopian airliner off the Comoro Islands causing 127 deaths, show that aviation confronts a wide range of security threats. The aim of this volume, published ten years after Lockerbie, is to assess the changing threats to aviation security. It is a sad fact that despite major efforts by certain states to enhance security, much more needs to be done to remedy weaknesses in international aviation security if further Lockerbies are to be prevented. The contributors examine threats and vulnerabilities in the light of recent developments in aviation security and consider the prospects for strengthening the response at national and international levels. The study is of obvious relevance not only to security and academic specialists but also to the international civil aviation community and national policy makers.