They can fly forwards or backwards or hover like a helicopter.

I can't keep flying back and forwards across the Atlantic.

My hand flew backwards and forwards like a shuttle on a loom.

Simon shook his head violently till the coarse black hair flew backwards and forwards across his face.

Words were flying backwards and forwards without concepts riding on their backs.

In a little time they came in sight of the enemy, who appeared flying backwards and forwards, as if not well satisfied with their ground.

Consider a helicopter which is flying forwards and about to make a turn.

Exactly the same situation applies when the model is flying forwards in calm, or windy, air.

He might risk his health by flying backwards and forwards between continents.

The little bird was flying busily backwards and forwards as fast as he could, carrying pieces of dry grass.