Assuming you could sneak a supercap onto a plane (roughly 30Wh/kg), using the maximum of your carry-on-weight and not exceeding it (usually ~10kg), you can easily have an energy potential equivalent to ~1/2 a stick of dynamite. How much you'll get out in the form of explosive force is debatable, but is certainly to be an order of magnitude above a battery as the discharge rates are several orders of magnitude faster.

However, the expected explosive force of home made liquid explosives is only on the scale of a stick of dynamite, it's certainly less obvious though.

Both explosions randomly placed are unlikely to down a plane, and are likely to be better used breaking into the cockpit than actually downing the plane.

I believe almost a 1/3 KWh high voltage power source could be of much more use than in its explosive force for an organised terrorist attack. However, most anti-terrorism procedures aren't designed to prevent organised terrorists, they're designed to prevent the many more morons with access to explosives.

Let's make the math a little more favorable. If the TSA caught 99% of liquids people try to bring through and then randomly tested 5% of them, the terrorist faces a 1% chance of success in each attempt, and a 4.95% chance of arrest. Assuming they repeat upon the most likely (liquids confiscate and not tested) outcome, they face an overall 16.81% probability of eventually getting the liquids through, and a 83.19% probability of arrest. Now, a 16.81% failure rate ain't great (and my assumptions are probably favorable), but that's why we need a layered security system.

On the other hand, if the TSA tests 0% of the liquids, the probability of eventual success jumps to 100%...

You can search for "Randall" on the page to find Randall's comment and TSA's response.

1. Remove tinfoil hat

2. Use ctrl+f