Hijacker's Strange Demand!

A man hijacks an aeroplane transporting both passengers (8 of them) and valuable cargo.After taking the cargo, the man demands nine parachutes, puts one of them on, and jumps, leaving the other eight behind. Why did he want other eight?

          I want 9!

Find the reason here! 

Source 

Hijacker's Safe Game!

And how did he play it? 

Had he demanded single parachute how can he be sure that it's not adefective one. He demanded nine with thought that cops would think that he wants to jump with all 9 passengers safely. So cops would not take risk of sending any defective parachute.