There were many rumours going around about the song and what it said in the lyrics.
Well, if you told me you were drowning, I would not lend a hand.
I've seen your face before, my friend,
But I don't know if you know who I am.
Well, I was there and I saw what you did,
Saw it with my own two eyes.
So you can wipe off that grin,
I know where you've been.
It's all been a pack of lies.
Rumours are that in Phil Collins (artist and writer of this song) in his youth, witnessed a close friend drown on a nearby cliff. Being too far away and unable to help, he saw a man walk close by to his friend drowning and just ignore him.
The song, In The Air Tonight, was supposibly written based on this event. It is also said that Phill Collins sang the song to the man who let his friend drown up on stage at his concert.
According to most internet sources, these rumours are all false. Phil Collins is said to have stated himself, " I just made the song up as I went along and it has no real meaning."