A detonator being inserted into a home-made bomb. The constituent parts of the bomb are the detonator, the explosive (in this case a plastic explosive) a timer and a small power source. The bomb seen here contains around 2kg of plastic explosive Comp C-4. This is similar in size to an equivalent Semtex bomb. This bomb is fairly crude in design, more complex electronic or barometric fuses are used by most terrorist groups. A bomb about half the size of this destroyed a Boeing 747 airliner in mid-air over Lockerbie, Scotland, in December 1988 causing the loss of 270 lives. The bomb had been packed into a small tape recorder.