Some of those flaws persist, so it's not possible to draw conclusions beyond that it won't be possible to bring printer cartridges on an airplane for the rest of time. So I'll point up some of the flaws and my questions.
Today's meme seems to be that the bombs were designed to explode in flight (WaPo, LA Times, Boston Globe). How do they know this? Unanimously, they quote British Prime Minister David Cameron, who simply stated that they were.
Now, if the reporters were sharp, they would know that there are several ways to make sure a bomb detonates on a plane: a pressure sensor to detonate at a given pressure, a timer set for a time when the plane is likely to be in the air, or a cellphone chip. All of these don't quite fit the facts given out so far for a conclusion that the bombs were to detonate in flight. The cellphone chip has been mentioned as a component in most reports; I believe I've seen a timer mentioned in early reports, but its popularity seems to be waning. I'm not aware that anyone has mentioned a pressure sensor.
In any case, a pressure sensor seems unlikely.
One of the bombs traveled on two passenger planes within the Middle East before arriving in Dubai. (Boston Globe; also WaPo)That means that the pressure to signal detonation would have been reached on those flights. Of course, it's possible the detonator didn't work.
The perpetrators need a lot of information to set a timer properly, and even that may well fail:
...with these freight flights sometimes the routing can change at the last moment so it is difficult for those who are planning the detonation to know exactly where – if it is detonated to a time, for example – exactly where the aircraft will be... (Guardian)A cellphone detonator would need to be in range.
One other clue:
The preliminary conclusion that the devices were designed to detonate aboard aircraft, and not at the addresses in the Chicago area, is based in part on the fact that the parcels were not rigged to explode upon opening. (WaPo)In any case, why bring down a cargo plane? The greatest reaction comes from the many lives lost.
Of course, it could be that the bomb designer/maker didn't think all this out and thus was not as "professional" as is being reported.
Unfortunately, the reporters don't seem to know much about bombs. The explosive, PETN, is pentaerythritol tetranitrate, not trinitrate, as was reported in many places over the weekend and persists into the Boston Globe account I've linked. It appears that copying is easier than checking. The error may have originated with an official source, but, because the reporters didn't catch it, it's not possible to tell whether that source misspoke or had other things wrong. And, although it's a small error, it raises the question of how well the reporters are doing on conveying other information.
I also find the statements (in multiple places) that PETN can't be detected by dogs or standard airport procedures puzzling. I don't know what dogs can detect, but I thought that those swipe things were put into a mass spectrometer that should be able to detect PETN. Does this mean that the chemically related nitroglycerine can't be detected, either? That puts a new face on the otherwise ridiculous liquid limitations.