The well-coordinated terrorist attacks on Sept. 11, 2001 presented the world with a new
aviation security threat: the capture of aircraft in flight to be used as human-guided missiles.
The two previous threats—hijacking an aircraft for ransom and putting a bomb aboard an
aircraft—had led to varying degrees of screening of baggage and passengers in developed
countries, plus some use of on-board security personnel on selected flights in some
countries.
In the wake of 9/11, governments in the United States, Canada, and Europe (at both national
and EU levels) implemented a number of additional aviation security measures, among them:
- strengthened (and locked) cockpit doors;
- 100% screening of checked baggage;
- more thorough screening of passengers and their carry-on baggage;
- increased use of on-board security officers;
- increased attention to air cargo;
- and greater attention to airport access control and perimeter control (...)
