What is the purpose of the bomber planes in Farenheit 451?
The bombers create a sense of tension, showing that there is something happening out in the world that the citizens of the city ignore. In the constant wash of TV shows, none of which have any plot or purpose, there is the background noise of an ongoing war; strangely, none of the citizens seem to notice or care. Montag finally wonders about the presence of bomber planes passing overhead, seemingly a daily occurrence:
"Every hour so many damn things in the sky! How in hell did those bombers get up there every single second of our lives! Why doesn't someone want to talk about it? ... Is it true, the world works hard and we play? Is that why we're hated so much? I've heard the rumours about hate, too, once in a long while, over the years. Do you know why? I don't, that's sure!"
(Bradbury, Fahrenheit 451, Google Books)
There is no focus on actual politics or world events, and the military planes flying overhead are just another constant in the lives of the citizens. It seems that the culture is in a state of constant war, but the government is striving to keep the populace uninformed. At the end of the novel, it is the bombers of the enemy which destroy the city; no matter how many bombers fly over every day, they are powerless to defend the city, and it is unknown if the government entity survived the attack.