Vigilantes etc...
Well, the idea, or something like it is already being mooted in the States - here a bit of plaigarism from the Avweb:
MISSILE WATCH...
Last Wednesday, The Washington Post reported the existence of a task force created to assess the ground-based threat to air travel and try to prevent the use of shoulder-launched ground-to-air missiles that could theoretically be launched against airliners from beyond the airport security perimeter. While military technology might provide some of the answers, the task force appears focused on enlisting the help of ordinary citizens to prevent such attacks. "There's a wide-ranging, active discussion about this issue," said Transportation Department spokesman Chet Lunner. According to the Post, the committee was working on the threat even before last November's unsuccessful portable missile attack on an Israeli airliner in Kenya.