One did the other night from the Roger Waters concert in Perth. I was there and watched it fly off into the night sky:
Pigs Really Do Fly Roger's pig escaped his leash in Perth on Friday night! The pig, the size of a bus floated across Perth skies after it escaped from the concert. Police say it appears someone may have deliberately cut the pig free. Police monitored the pig's flight to ensure the airways were not disrupted. It made its way into the swimming pool of a house in the Perth southern suburb of Bateman some 15 kilometres away.
See, they do fly.