Signal flare

The Signal Flare is a common tool used in the Military by the Garrison and the Survey Corps. The signal flare has a variety of uses depending on the mission.

Uses
While the Signal Flare has many uses, its main purpose is long distance communication. The Garrison uses it as a way to inform the higher-ranking officers how their mission is going while the Survey Corps uses it as a way to communicate (often in the presence of Titans) to the rest of the legion.

Ammo
The ammo used depends on the mission at hand. The ammo the Garrison uses is the following:
 * Green - Mission started.
 * Red - Mission failed. (Unless Yellow Flare is spotted some time after Red)
 * Yellow - Mission successful.

The ammo the Survey Corps uses for the 57th expedition beyond the Walls is the following:


 * Red - Titan spotted.
 * Black - Deviant Type Titan spotted.
 * Purple - An emergency of some kind.
 * Blue - An order to retreat.
 * Green - Change direction of the formation: Fired by the commander in one direction to indicate a change in the direction, and then repeated by the relay soldiers.
 * Yellow - This lets everyone know that the mission has been terminated, be it successfully or failed.
 * While leading the Female Titan through the Forest of Giant Trees, Levi used a special shell that emitted a high-pitched noise.