While it is physically possible to knit on a plane, sometimes there are some obstacles in the way in terms of airport security. According to the Transportation Safety Administration (TSA), which oversees airport security in the United States, people are allowed to take knitting and needlepoint projects on aircraft, but there are some caveats. Safety officials also reserve the right to confiscate any items which they think may be dangerous, which means that knitting needles and tools may be confiscated, even if they are technically allowed.
For people who do want to knit on a plane, circular needles should be used, ideally circular needles with needles which are very short, to underscore the lack of danger involved. Metal needles should be avoided, with plastic and bamboo being preferred, and blunt scissors or customized airplane scissors should be taken along. Keeping knitting tools in a clear plastic bag so that they are easy to examine is also recommended.
From a practical point of view, it is a good idea to take small projects to knit on a plane, for convenience and the comfort of other passengers. It can also be a good idea to have a partially completed project on the needles, to prove to airport security that the intent really is to knit, not to stage some sort of attack on the aircraft or cabin crew. Alerting security officers to the fact that there are knitting needles in a carry on bag is also a good idea, so that they are not alarmed when the bag goes through x-ray.
The TSA recommends that knitters pack a self-addressed envelope in their luggage so that if an officer determines that knitting supplies are not safe to take on a plane, the needles and other supplies can be mailed, rather than surrendered to the safety officials. People may choose to mail their projects on the needles, or to carry a crochet hook so that the project can be taken off the needles and carried on the plane while the needles are mailed home.
Since airport security officials are allowed to use their own judgment when assessing potential threats, people who want to knit on a plane should remember to keep cool in discussions with officials. Becoming agitated or angry will not accomplish anything, and it could result in being barred from a flight, if the officer becomes concerned about safety. Most safety officers are happy to allow knitting on a plane, especially when it is in the hands of someone who is friendly, relaxed, and courteous.