I found this in a
The Jerusalem Post article, dated June 2015; however, I have no idea if the information is current. You may wish to email the author, a Jerusalem travel agent, at the linked email address (I've had at least one email exchange with him several years ago).
Delta Airlines for examples requires it on all Transatlantic flights until they are 15, American Airlines, United and El Al Israel Airlines permit it from age 12.
All offer the service only on nonstop flights. One cannot send an unaccompanied minor on any of the four North American airlines that fly between the US, Canada and Israel on any flight with a connection.
Plainly speaking if you want to send a child or grandchild, for example to or from Chicago as an unaccompanied minor, Air Canada, American, Delta and United will not accommodate you as they don’t fly nonstop. It can only be accomplished using a European airline who will shuttle your loved one from one plane to another in a European city.