Hey hun,
I flew a 9hr flight with Arianna when she was 14mths so a little older than your LO, but what I took on the flight for her was...
Winnie the Pooh musical book
Disney Toy Phone (it has Mickey Mouse, Higglytown Heros...)
Crayola Colour Wonder (this is magic pens that old work on the supplied paper so LO can't colour in the furniture etc. - most supermarkets have this)
Then, also take books,blanky, teddy etc.
If he is a fan of a certain programme (like in the night garden, etc) and you have an i-pod, how about loading some films on to it - I am in the states just now and I put Wall-E, Doodlebops and Horton Hears a Who on mine to keep Arianna amused (again tho, she is older, now 2.5yrs)
Hope this helps you