Originally Posted by mad_machine
exactly.. in am emergancy situation, you can flash anything you want at a passing airplane to get their attention. It is perfectly legal.
You shouldn't do that, I don't care what the circumstances are. It's unlikely to have you found by anyone because you would essentially be blinding everyone in the cockpit, which not only means they won't see you, you actually endanger the safety of the flight. This is extremely dangerous, which is why being caught doing it carries such a significant penalty.
When you flash a laser pointer at an airplane (it doesn't have to be an airliner), the laser spreads through the glass into the cockpit, the effect is very disorienting and dangerous to the safety of the flight.