On December 11, 1994 in Philippine Airlines Flight 434 a bomb designed to explode the center fuel tank of the Boeing 747 exploded in flight over the ocean killing one passenger. The bomb was planted by terrorist Ramzi Yousef. He planted the bomb in the flotation device under seat 26K that is normally directly over the center fuel tank. This was described in Phase I of the Bojinka plot. Fortunately, this particular 747, formerly operated by Scandinavian Airlines, had a different seating configuration and seat 26K was two rows forward of the center fuel tank so that the hole in the floor punched through to the cargo hold instead and spared the plane from a fiery explosion.
United States prosecutors said the device was a "Mark II" "microbomb" constructed using Casio digital watches as described in Phase I of the Bojinka plot, for which this was a test run. On Flight 434, Yousef used one tenth of the explosive power he planned to use on eleven U.S. airliners in January 1995. The bomb was, or at least all of its components were, designed to slip through airport security checks undetected. The explosive used was liquid nitroglycerin, which was disguised as a bottle of contact lens fluid. Other ingredients included glycerin, nitrate, sulfuric acid, and minute concentrations of nitrobenzene, silver azide, and liquid acetone. The wires he used were hidden in the heel of his shoe, below the detectable range of the metal detectors used by airports of the day.
Manila police were able to track the batteries used in the bomb and many of its contents from Okinawa back to Manila. Police uncovered Yousef's plan on the night of January 6 and the early morning of January 7, 1995, and Yousef was arrested a month later in Islamabad, Pakistan, by the Pakistani Inter-Services Intelligence (ISI) and U.S. Diplomatic Security Service, then extradited to the United States.
This was 1 year prior to the center fuel tank exploding on TWA 800. High explosives residue RDX, PETN, and nitroglycerine were found on a piece of floor board in the same general area of TWA 800.