Jinns aren't really the most reliable of creatures. They're not likely to provide every snippet of information and they tend to lie. That's if it is due to a jinn.
That is a possibility I won't discount.
It could be due to a jinn cos they are able to influence dreams - like the ones the kid use to have. Also, the fact that he didn't seem to remember what happened when his parents would ask him is another symptom that's common among possessed people. They tend to forget what they talk about when possession overtakes them.
Another thing that comes to mind is qareens (we all are assigned a companion from the jinn that whispers evil into our hearts and guides us toward doing sinful things). If that pilot died and his qareen is wandering the Earth, maybe he took a liking to the kid and decided to bring out memories of his dead human companion lol. :hmm:
But yeah, it isn't impossible that he could have somehow stored that information in his subconcious after a museum trip or something.
From personal experience, I can say with 100% certainty that they do occur. Allahu alam to the frequency, but I know black magic is rife in places like India, Pakistan and Morrocco and usually, jinns are sent into the bodies of victims to bring out the affects of this magic. The jinns possess the victims and make them ill or whatever, without them even knowing they are possessed.