It is true that in most cases (unless they are too heavy) that chickens are indeed able to fly. However it should be noted that they are only able to fly for short distances at a time, on average from about three to four feet. Chickens usually fly to flee from danger or a predator, in which case they may be seen flying vertically up to an object, or just horizontally to get out of the way. They have also been known to fly when not represented by danger, for instance simply in experimenting around their surroundings. Maybe they’re bored.
Chickens can also fly up to roosts as turkeys do, though some breeds of chickens have been known to have better flying ability compared to others. Chickens that weigh too much are not able to fly, due to the fact that they are simply too heavy. Also contrary to what some people may believe, chickens are not able to fly to migrate. They are not migratory birds and do not have this ability, also if you remember they are unable to fly for long distances. It would take a chicken forever to migrate even if they could.