The Blue Alarm (or code Blue) is triggered by the commander or computer of a spaceship when the ship is preparing for a landing. Blue alert level is used when Intrepid-class ships are about to land on a planet. In addition, it is used on ships of the Prometheus class when the ship splits to go into attack position, in addition, it is used when the life support on a deck is about to fail.
It can also be triggered automatically by the computer to warn of a failure of the life support system on one or more decks. However, the alarm is limited to the affected area. In this case, it must be evacuated immediately. (TNG: The Unequal Brothers)
Shields and weapons are usually deactivated during a landing or docking process. Intrepid-class ships, such as the USS Voyager, turn off the warp core when landing on a planet and also blow the plasma out of the warp nacelles. (VOY: The 37s)
Tuvok calls out the blue alarm on Voyager when you land on a Class Y planet. (VOY: Demon)
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