Need help identifying this story

Some years ago my wife and I saw a PBS adaptation of a short story dealing
with a young flyer joining the RAF at the front lines during WWI.

The young man discovers that the older veterans are standoffish. He feels
they share a secret they won't share with him. After his first battle, and
his first taste of losing comrades, he discover just what the terrible
secret really is.

I know this is a lame description. If you recognize the story, could you
please tell me the title? I'd appreciate it.

AJ