I asked this question at Arts & Craft, but it might be more relevant here.
Can I take knitting needles on an international flight?
This tends to vary by country. For example, from Air New Zealand:
Can I take knitting needles and/or crochet hooks onboard?
You are able to take knitting needles and/or crochet hooks onboard if travelling domestically throughout New Zealand.
If you travel internationally you are able to take them onboard out of New Zealand but if you are transiting and flying through another country you will need to check with their security as this policy is country dependent.
So, you will have to check the security policy of both your origin and destination, as well as any stopovers.
My mother took knitting needles often as she traveled internationally, for something to do when sitting - even quite recently (last couple years). She mentioned that she has had less trouble, and was less often asked to dig them out of her bag and show them, when they were at the top of her bag and visible (and entangled in yarn), instead of packed down between things - probably because when they were packed away, they looked more "hidden". At least one pair surprised me when it went through, being about ten inches long and hollow metal - but in the context of the yarn and half-completed weave, I suppose it didn't seem threatening to the security who looked at it.
It would probably be wise to choose smaller knitting needles, and perhaps a pair that isn't too dear in case you do run into a security person who objects. You should check any lists to see if it's actually forbidden, as well - but it will often be up to the discretion of whoever is checking. You may have better luck with a half-completed project tangled into your needles than if your tools are stored separately, and it might be better if your needles are obviously plastic, on the smaller side, or a bit flimsy - although, as I said, it is possible to get through with big metal knitting needles if the security people are permissive.
I do it all the time! I find that people are less weird about it if you bring circular needles.
Just in case - find the flight regulations for your country of origin and your destination. Print them out so that if someone gives you trouble you can just hand them the regulations. I've heard this referred to as the "Flying Granny Clause" (lol I'm 29 and a flying granny).
There's some more information in this blog post.