Summarize:

You may be able to get away before a goose becomes too aggressive if you see the warning signs of an attack. Pay attention to any potential signs of aggression when you're near a goose.  At first, a goose will bend its head back slightly. This indicates aggression. If the goose then bends its neck out straight, this shows the aggression is increasing. If a goose is about to attack, it will pump its head up and down. Geese may hiss or honk as well if they are becoming aggressive. If you notice warning signs of an attack, leave before the goose begins to chase you. If the goose sees you're backing away, it may decide you're not a threat. Back away slowly until you're a good distance from the goose and it's stopped making aggressive gestures. In the event the goose starts chasing you, back away slowly. Stay faced towards the goose and use your peripheral vision to guide your movements. Make sure to avoid anything you may trip over, as this may give the goose reason to attack. If you appear frightened or upset, a goose could take this as a sign of aggression. It's a good idea to maintain a calm, neutral demeanor when backing away from a goose. If you're struggling to remain calm, take a few deep breaths as you back away. Keep in mind that, while geese can be territorial, an actual physical attack is very rare. In the event a goose bites you or hits you with its wings, seek medical attention. Geese are strong, and can cause injury when provoked. You may require stitches or a cast if a goose attacks you. Go to the emergency room for assessment as soon as you get away.
Watch for warning signs of an imminent attack. Leave before a goose begins to chase you. Back away slowly if the goose becomes aggressive. Remain calm. Seek medical attention if you're injured.