Some scary background from Tony Harris of CNN (with the caveat that it's not yet certain "Al Qaeda," whatever that name means these days, is behind this):
In fact in 1994, al Qaeda actually pulled off a test run of one of these bombs that was assembled on an airplane using liquid explosives and a detonator. In that case, it was a Casio watch. Here the thinking is that it might have been one of these electric key fobs.
So he says ... we're only talking about a small amount of explosives. Look at what Richard Reid, the shoe bomber, had. That was only a small amount of explosives, yet it was enough to bring down a plane, and that was much evolved from what happened in 1994.
In 1995 and 1996, there was a plot to bring down up to 11 transoceanic flights from the Pacific into the United States. This plot is very reminiscent of that. So you begin to see where there's an evolution of the al Qaeda playbook here.
Not sure how testing this out 10 years ago and doing it today represents an "evolution" but it's an interesting data point.