I've had no problems. The last time I flew I carried a set of circs that happen to be resin with a plastic cable (from my Denise interchangeable set). But generally, they allow knitting needles, crochet hooks and small scissors (just recently added the scissors-but i recommend taking a blunt nosed one or a yarn cutter pendant). Your best option is to go online to the airline you are using and search under "restrictions" or special rules or whatever and browse what their policy is. Also, print that and have it with you so if someone at the airport says otherwise, you can back yourself up with the company rules!
Hope that helps!