The song is about drugs, yes, but it's an intervention song, not a song to glorify their use. "Antifreeze" is heroin, "aeroplane" is marijuana, and when he sings "Spread your wings and share the pain", the singer's saying that the individual he's apostrophising should get help. The term "fly away" means to overcome the drugs' hold on one's life, not to give in to the "easy way out" and refuse to change.
The song is about drugs, yes, but it's an intervention song, not a song to glorify their use. "Antifreeze" is heroin, "aeroplane" is marijuana, and when he sings "Spread your wings and share the pain", the singer's saying that the individual he's apostrophising should get help. The term "fly away" means to overcome the drugs' hold on one's life, not to give in to the "easy way out" and refuse to change.