Is This Bird Capable Of Flight?

My daughter and I took our cars to TGM in Fleet, Hampshire today. We left them with Tom and went to The Heron On The Lake for lunch. A family of Canada geese approached the weir. Two silly goslings toppled over the edge into a slippery, steep-sided gully. They tried over and over again to clamber back to the lake, calling to their parents constantly. Our mate scrambled down to try to rescue them but they disappeared into a culvert.  We wondered why they didn't fly out but having looked at the above pic that I took just before one of them overbalanced it seems that their flight feathers aren't fully developed. :(