As airline security has evolved, so have terrorists' attempts to strike at aircraft.
Suitcase bombs
The 1985 Air India bombing was the deadliest aviation attack until 9/11. Sikh extremists in Vancouver placed a suitcase bomb aboard Air India Flight 182, killing 329 people. Two baggage handlers in Japan were killed by a separate bomb that originated from the same operation. Similar methods were allegedly used by Libyan terrorists who destroyed Pan Am Flight 103 above Lockerbie, Scotland, killing 259 people in 1988.
Nitroglycerin
Highly undetectable, this volatile compound was to be used in a thwarted attack that was a forerunner of 9/11. Code-named Bojinka, this al-Qaeda plot envisioned 11 bombs exploding simultaneously on 11 planes flying in Southeast Asia. Authorities in the Philippines foiled the scheme by raiding the terrorists' apartment. A 1994 test run for Bojinka killed a Japanese businessman after the lead plotter stashed a timed bomb under his seat before getting off. The explosion failed to crack open the plane.
Fuel-filled planes The Sept. 11, 2001, hijackers turned four U.S.-based passenger planes into jet-fuel-laden missiles, after they smuggled collapsible box-cutting blades on board to help them break into the cockpits and take control of the aircraft. Almost 3,000 people died as planes smashed into the World Trade Center in New York and the Pentagon in Washington and crashed in a field in Pennsylvania.
Shoe bombs
In December, 2001, Richard Reid lit a match aboard American Airlines Flight 63, flying Paris to Miami. Suspicious passengers subdued Mr. Reid before he managed to ignite a potent explosives cocktail hidden in the soles of his shoes. He was sentenced to life imprisonment in 2003.
Shoulder-launched missiles
Terrorists fired missiles at an Israeli-chartered jetliner leaving Mombasa as suicide truck bombers attacked a hotel. The missiles missed, but the truck bomb killed three people.
Binary explosives The idea behind the thwarted 2006 transatlantic plot was apparently for a series of operatives to mix two or more relatively inert chemicals while aboard planes. The aim was to create deadly explosive cocktails, killing the operatives and everyone else. Colin Freeze
