As a vegetarian I always order a special meal when I fly, but you should be warned if you fly on an Asian airline or to an Asian destination then you must specify what kind of meal you want. Often they have choices of an Asian vegetarian meal, which can be too hot and spicy for some people. I once had one, took one mouthful and had to run down to the galley for water it was so hot. Fortunately they had spare vegetarian meals such as pasta that I was able to eat instead. Always check because local curries are very hot, and may not be suitable if you are not used to them.