baseball

It's not really that long of a time period. It will take a while. I would have thought about 5 minutes, but I guess they are saying 3.

Any explosive device will yield some varying results depending on the net explosive weight of the device, amount of flammable materials as opposed to blast, and the amount and type of smoke produced. Also, the various normal routes of airflow and abnormal routes due to aircraft damage and system degradation will make certain compartments more smokey than others.

The device, If it was one could have been small enough to produce critical system damage and an ever widening hole in the fuselage. While not big enough to blow it out of the sky, it may have been big enough to cripple it and the sustained aerodynamic loads and sheer speed of the plane in flight could have ripped it apart over a period of a few minutes.

the smoke produced would have likely been both localized initially and spread via ventilation, but dissipated quickly after depressurization.

I still lean towards a device. Small, yet powerful. Something plastique perhaps. These blasts essentially yield two blasts in one. One outward blast of explosive gasses and one inward.

My biggest fear is that the bad guys will start smuggling this stuff in small amounts within their body cavity, IE, their butt-hole and remove it in the lav and assemble it in there during the flight. it's malleable, flexible, and stable. Probably all you need is enough to fit inside a good sized cigar to do the job.