The hangar deck is where a battlestar's fighters and support ships, such as Vipers and Raptors, are stored and maintained between missions. The hangar deck is located under the landing bays of each flight pod.
Munitions for the Vipers and equipment for the Raptors are also kept on the hangar deck. Basic repairs take place on the hangar deck. During Condition One alerts, pilots scramble to their fighters. The deck crew pushes their fighters out into the launch tubes, which are accessible through doors of the hangar deck.
If a launch is aborted, the deck crew is caled upon to pull the fighter out of the tube for quick repair. The hangar deck is basically as well-manned as the deck of any aircraft carrier.
Chief Tyrol is in charge of the repairs and other work done on the hangar deck.
Other special space fighters, such as captured Cylon Raiders, Heavy Raiders, and the experimental Blackbird are stored away in the hangar deck as well.