If you have a credit card with a limit that can take it, you can do a lengthly airport gate-area visit, which might help, as it will let him see a lot of other children happy and excited to be going on an airplane ride. Watch the planes safely landing and departing, eat at the airport, just generally make a day of it. Best to do it without any siblings along; that will make it more special and avoid the possibility of teasing.
As airports no longer allow people into the gate area without a ticket, the trick to getting to the gate area is to buy full-price, fully refundable tickets, do your time at the gate, then leave, go back to the counter and ask for a refund. (Obviously, you want to buy a ticket for a late flight and then go to the airport several hours before it departs, so that you can leave the airport and ask for a refund before the flight actually leaves. There is usually a bit of delay in getting your CC refunded, so you may have to float the balance for one month. If you do this, do be *absolutely* sure that the ticket you buy is fully refundable with no restrictions at all.)
