It depends on chance, and the honesty of the individual who finds the item.

For your amusement, here are the high-value items I've left on aircraft in the past couple of years, and the outcome:

1. Credit card left in my seat in J on United in Las Vegas. Returned to me by the pilot, who was hunting for me through the terminal. (I wrote an awesome letter to customer service over that one!)

2. iPad left in seat pocket in J on Air Canada in Chicago. Returned to me after an FA found it and turned it in to ticketing so I could pick it up a couple of days later upon my return.

3. Bose Headphones left in seat pocket in J on Austrian Airlines in Vienna. Never seen again. The airline doesn't deal with lost goods - whatever they find they turn into lost & found. I emailed lost & found and they never saw it.

In the two cases where items were returned, the airline notified ME before I even noticed the items were gone. It sure doesn't hurt to contact the airline and the airport lost & found, but the odds of the item turning up decline with each passing minute. Good luck!