The first single on Phil Collins first record in 1981 and his first ever single. Urban legend has it that the lyrics were telling a story of how Phil was watching somebody drown but was too far away to do anything, however he saw somebody close enough that could have done something and didn't. Then, Phil invited the guy that wasnt drowning to one of his shows, gave him a frontrow seat, and sang the song directed to him. while the stories may vary, Phil himself claims the songs lyrics were random and the stories are all fake.
from the song "Stan" by Eminem, 1990 something:
You know the song by Phil Collins, "In the Air Tonight"
about that guy who coulda saved that other guy from drowning
but didn't, then Phil saw it all, then at a show he found him?