If a warning message via a specific warning medium (such as television, radio or smartphone) is not perceived by a person in the danger environment, or if a warning medium fails, warnings are issued simultaneously via a variety of other warning media (such as city information boards, warning apps, loudspeaker trucks and websites). The more warning means that are included in the warning means mix, the greater the probability that a warning message will reach people in Bavaria.
In addition, the mix of warning means makes it possible to transmit warning messages in different ways. Used together, the individual warning means complement each other. For example, a siren can spread a warning loudly, but only single signal sequences are possible. The information content of a message in a warning app or on the radio, on the other hand, is significantly higher. It is precisely the important initial recommendations for action, such as how those affected can protect themselves from a danger in the first moment, that can only be presented in these ways. And finally, warnings can be disseminated by acoustic, visual and haptic means (e.g., the vibration alarm of a smartphone).
For the general warning of the population, the security and disaster control authorities resort in particular to the following means:
- Official danger announcements and danger notifications via radio,
- Sirens, which can also be used to broadcast the signal "Switch on radio and listen for announcement",
- Cell Broadcast,
- Warning apps.
In the event of disasters, other damage events below the disaster threshold and large-scale hazard situations, as well as in the event of siren false alarms, it may be necessary to warn and inform the population on a supra-local basis. For this reason, the security and disaster control authorities as well as the Bavarian police can arrange for announcements to be made via radio using a defined procedure; subtitling on television is also possible.
In the case of radio announcements, a distinction is made between official danger announcements, which are broadcast immediately and in full by the radio stations, and danger announcements, which provide information at the next possible opportunity (e.g. in the news) about expected dangers, damage situations and, if applicable, expected consequences.
Official danger announcements or danger messages can be transmitted by the safety and disaster control authorities - if necessary with the involvement of the integrated control centers - via the Modular Warning System of the Federal Government (MoWaS) and via the operations centers of the Bavarian police to the radio stations connected to the traffic warning service. If the warnings are for forest fires or severe weather, the German Meteorological Service sends them directly to the radio stations.
Sirens are also used to warn the population, primarily in areas or in the vicinity of facilities with a particular risk potential.
Bavaria has defined the meaning of the siren signals used in Bavaria with the Ordinance on Public Acoustic Signals. The most important siren signals are
- the alarm in case of fire and other emergencies, which serves to alert the emergency forces of the fire departments.
Signal: three times in the height constant tone (continuous tone) of twelve seconds duration, with twelve seconds pause between each tone.
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- the alarm intended to prompt the population to pay attention to radio announcements on the occasion of serious threats to public safety.
Signal: rising and falling wailing tone of one minute duration.
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In areas where sirens are available to warn the population, the public is usually informed from time to time about the siren signals and their meaning in brochures or on the Internet sites of the competent authorities. In addition, there is an annual nationwide test alarm in the first half of the year (second Thursday in March) and the nationwide warning day in the second half of the year (second Thursday in September), in which every municipality that has appropriate sirens can participate. These test alarms serve not only to
The purpose of these test alarms is not only to test the function of the sirens, but also to inform the population about the importance of warning messages in general, and of the siren signal in particular, in preparation for broadcast announcements.
With Cell Broadcast, the signaling channels of the cellular network are used for message transmission. Individual addressing is not necessary. Alerts are sent from the antenna like a broadcast signal to all devices logged into the cell and received by them. With cell broadcast, the wake-up effect is significantly increased. A warning message of warning level 1 (highest danger) triggers a perceptible signal tone even on smartphones that are set to silent in order to respond to a warning message.
The advantage here is that all persons in an area who are carrying a mobile radio terminal set up for this purpose and ready to receive can be reached anonymously as recipients of a warning message. In the event of a hazard, all persons within the affected radio cell who are carrying a mobile communications terminal that has been preconfigured and is ready to receive a warning will receive a warning in the form of a cell broadcast message on their mobile communications terminal (see: related links).
In addition to radio announcements and sirens, loudspeaker vehicles, digital city information boards, passenger information systems and smartphone apps are also used to warn the population.