An jihadi terrorist boards a plane disguised as a passenger and sits alongside a severally ill 9 year old Christian boy ?

It might be a good story, but what really matters is the talent, skill and natural ability of the writer.

At the moment, you don't have those qualities.

'Severally' means 'separately or individually; each in turn' or 'many times; repeatedly'.

Also, how can he be 'disguised as a passenger'?  He IS a passenger.  One who travels on any form of transport IS a passenger.

Spend a few years working on your language skills and reading hundreds of very good, well-written novels.  Maybe, after that, you'll have learned enough to try writing one of your own.

Good luck!

You're wasting your time. There are no professional, successful authors here. 

The problem I see is that such a terrorist is likely to act while the fuel tank of the plane is still pretty full.  If you can get around that issue - and I expect you can - it could work.

Note that some terrorists get involved not out of malice, but because they have committed some sin they want to expiate, or simply because they are suicidal and want to die without going to hell.  

You can look it up - Israel has captured a good many attempted terrorists and found out their motives.

How did they disguise the plane as a passenger?

Absolutely not.

No one is going to publish or read your book. Other racists are too lazy to read it also.

it sounds like a good idea to me