The first plot was a scheme to kill the Pope due to arrive in mid January, 1995. The second plot was the hijack airliners-fly-them-into-buildings scenario that was fulfilled on 9/11 and plot three was Bojinka; reportedly named by Yousef after the Serbo Croation word for Big Noise.
This was a non-suicide plot in which Yousef and his three cohorts, Murad, Wali Khan Amin Shah (a confident of bin Ladens) and Ramzis uncle, Khalid Shaikh Mohammed would board the first leg of a series of U.S. bound flights heading from Asia. On the initial leg of each flight they would smuggle on the innocuous components of an ingenious bomb trigger Yousef had designed. Powered by a Casio watch and utilizing diluted nitroglycerine to be ignited via a broken bulb initiator, the IEDs (improvised explosive devices) were to be placed under seats (in the lifejacket pouches) located above the center fuel tanks of 747s.
The plotters would then exit after the planes touched down and the IEDs would blow hours later as the planes jetted back across the Pacific. Yousef had intended this to happen on 11 flights and he even wet tested one of the Casio-nitro devices on Philippines Airlines Flight 434 on the first leg of a flight from Manila to Cebu in the Southern Philippines on December 11, 1994.
At the time he planted the device under seat 26K, in a row just shy of the center fuel tank. On its way to Japan the bomb blew, killing (Haruki Ikegami) the passenger in 26K and blowing a hole in the cabin floor, but it missed the fuel tank and the plane landed safely.
But Yousef realized that if he just moved the devices a few rows forward they would serve as blasting caps to rip open the fuel tanks so he plotted with Khalid Shaikh Mohammed, Murad and Shah to plant the Casio-nitro bomb triggers aboard up to 11 jumbo jets exiting Asia.
Yousef was captured in February 1995 after a fire in his Manila bomb factory. Murad was captured a month before and Shah was eventually arrested after first escaping from custody.
How did you come across this?