On October 29, 2010, two packages, each containing a bomb consisting of 300 to 400 grams (11–14 oz) of plastic explosives and a detonating mechanism, were found on separate cargo planes. The bombs were discovered as a result of intelligence received from Saudi Arabia’s security chief. They were bound from Yemen to the United States, and were discovered at en route stop-overs, one at East Midlands Airport in the UK and one in Dubai in the United Arab Emirates.

One week later, al-Qaeda in the Arabian Peninsula (AQAP) took responsibility for the plot, and for the crash of UPS Airlines Flight 6.  U.S. and British authorities believed Anwar al-Awlaki of AQAP was behind the bombing attempts, and that the bombs were most likely constructed by AQAP’s main explosives expert, Ibrahim Hassan al-Asiri. The bombs were probably designed to detonate mid-air, with the intention of destroying both planes over Chicago or another city in the U.S. Each bomb had already been transported on passenger and cargo planes at the time of discovery.

CNN investigates the al Qaeda printer bomb plot and the potential damage the bomb could have caused.

Source: https://en.wikipedia.org/wiki/Cargo_planes_bomb_plot

Source: https://www.youtube.com/watch?v=Uu70Ni3S-Wk