Aviation Disasters,Plastic Planes Solution

I have watched many TV programmes about passenger planes crashing and
breaking up and being ingulfed in smoke and fire and many people dieing
and how the owners try to make planes safer which looked liked hopeless
inadequate attempts they were suggesting and people would still die the
way planes are still built and i was wondering why passenger planes and
the fuel tanks are not made of composite plastic?

I have experimented with plastic and found the corkscrew part of coke
bottles very strong and cheap plastic,i had the idea that just like
moulds are made to make the coke bottles,giant moulds could be made to
mass produce airplanes made of this strong plastic,if the plane crashed
it would not disintegrate or catch fire and if it crashed at sea it
would float and could be towed back to land by a ship.

http://www.scaled.com
I came across this composite plastic website who make small plastic
planes and who made the composite plastic space shuttles for Richard
Branson.

Stellios of easyjet should be interested in this idea aswell?