Alerts show small triangle icons on the right of the quickbar and play a sound unless muted. Warning icons are shown directly on a given entity. Alerts globally inform the player of the status of the factory, including missing construction material or entities being destroyed, warning icons show the status of a given entity, such as low power or ammunition.
Alerts last 10 seconds and can be clicked to show the position of the entity which caused the alert on the map. Hovering over an alert enlarges the associated alert icons on the map and shows arrows on the screen edges that point to the positions of the entities that caused the alert.
Configuration of alerts
Alerts can be turned on and off, and muted/unmuted using the /alerts command in the console. This command does not disable achievements. The syntax is
/alerts <enable/disable/mute/unmute> <alert type>
Available alert types are: entity_destroyed, entity_under_attack, not_enough_construction_robots, no_material_for_construction, not_enough_repair_packs, turret_fire, no_storage, train_out_of_fuel, fluid_mixing and custom.
Custom alerts are alerts that are displayed using the programmable speaker.