Glider traffic jam in Normandy

Several things come to mind when I see this picture. How terrifying is it to pilot one of these things, knowing you have one chance to get on the ground safely? How do you manouver this heavily loaded, unpowered device- full of your friends, surrounded by a crowd of similarly descending machines?  How much training did a glider pilot get, considering they made just one flight? How brave do you have be to do all of the above- under fire?