It all depends on the TSA agent/screener
. I have to knit and listen to my ipod audiobooks while flying, otherwise I make an awesome impression of a statue for as long as the flight
I always bring a small carry on full of sock or lace weight yarn; aka the more complicated the pattern, the more I stay "extremely focused". Since I don't really know what I'm actually going to knit; I usually bring a complete 16" circular set. If I can't knit: I don't fly
Anyhoo, I've been stopped before
. Ended up locking up my knitting bag at the airport until our return. Fortunately, I had an audiobook that required alot of focused listening in order to comprehend everything.
Knitters be aware of the possibility of your project and needles being taken away.