OP I hope you don't fly off on holiday. That is most definitely an avoidable luxury. Jet fuel is almost identical to diesel fuel and the clouds of burnt fuel from planes taking off spread out over schools and houses. Let's stop holiday flights immediately!
GladAllOver, well, I'm not the OP, but I don't fly on holiday, we take the train (which has its own impact, of course, but is still better than flying). But you are right - making people think about the impact of their flights is also a good thing.
However, where I'd disagree (only a little bit - I do agree it's a problem) with you is in targetting families who take one holiday abroad a year. That does have an impact, on the environment, it's true, but they really aren't the main problem, and it's a hard thing to ask people to give up, especially for people with relatives abroad. (I have family abroad too, and miss seeing them terribly.)
It's the frequent flyers who are the real problem - the people who pop over to their Tuscan villa every other weekend, or whatever. 15% of people take 70% of the flights! If anyone who took more than one or two flights a year was taxes very heavily for these subsequent flights, for example, that really might be a start on tackling the problem.