Fake threats to flights

How severe a penalty should a culprit receive for making a fake bomb threat?

This has become an urgent question after two separate incidents last week disrupted 16 domestic flights.

Two suspects have been apprehended and will stand trial. But even if they are found guilty, they will probably receive a prison sentence of less than five years, just as their predecessors did, even though the maximum prison sentence for such a crime is 15 years.