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.
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.