CNN CNN Newsroom Live November 5, 2015 07:34:00
Explosives used by al qaeda. authorities believe isis used a more conventional device. a source celling cnn it may have included a barometric pressure switch. al qaeda has targeted passenger planes four times since 2011. one attempt foiled by passengers on board. a plot by british extremists who hide explosives in water bottles was disrupted. and then the underwear bomber failed to properly detonate explosives as his plane was landing in detroit. a year later, explosives were discovered in two printer toner cartridges on usp planes. and a master bomber claimed credit for both incidents.