The airlines have oversold their frequent flyer miles and so now all you can get for being a loyal flyer is getting on the plane ahead of everyone else.
If you're like me and fly whatever is cheapest, then you're not in one of these programs and you end up at the back of the line praying there is still some space for your carry-on.
If you are worried about fitting your carry on in the bin then you need to take a lesson from my travel hero Ralph Potts
http://www.rtwblog.com/
Around the world with no luggage. He’s a great travel writer as well.