Of the 10. September should be the acid test for warning civilians in the event of a disaster. Sirens should sound nationwide, warning signs should light up and smartphones should sound the alarm. At exactly 11 o’clock the spectacle should begin, the all-clear was for 11: 11 clock set.

Warning apps that push messages to users have now become an important component of civil protection. However, the well-prepared test failed completely surprisingly and drastically, because many smartphones did not issue an alarm message.

That would not be so fatal if Germany had not decided after the end of the Cold War to dismantle the warning sirens that were permanently installed in many places. Only a few municipalities still maintain a siren network that could alert the population promptly in an emergency. Modern technical solutions should have taken their place for a long time, but they do not work as they should.

That is why today in many places there are still warnings like many decades ago: if an urgent emergency suddenly arises, the police are put on the march with loudspeaker vans. However, there are major differences in how the states and municipalities approach the topic: Hamburg, for example, which is always threatened by storm surges, still maintains a functioning siren network and warns of impending storm surges in the port area with gunfire.

Important wake-up effect Warning apps are an important component because they make a noise in the middle of the night even when the mobile phone is muted, for example because of windows must be closed in the event of a fire or there is a risk of flooding The wake-up effect is very important, especially at night; Announcements on the radio or warnings on display boards do not reach anyone who is currently in bed. However, the effectiveness of the warning apps depends on the fact that as many users as possible also install them and configure them correctly.

There are many ideas on how to send wake-up calls in other ways in an emergency. For example, one day the horns of smart cars or networked smoke alarms in households could wake those affected from sleep. Since smart city applications are not yet really widespread in Germany and there are often no standardized interfaces to such systems, it will be many years before this can be implemented in practice.

The warning apps are also a smart city application in the broader sense. They work location-based and deliver the warnings in a targeted manner – that’s why they need access to the location data of the smartphone in order to warn dynamically for the respective location. For most users, it would make sense to also enter the coordinates of their place of residence or work in order to receive warnings for this if they are currently traveling elsewhere.

Central warning system The warning messages from the disaster control authorities in the districts and urban districts as well as the situation centers of the federal states and the federal government are centrally stored in the MoWaS (modular warning system) of the Federal Office for Civil protection and disaster relief (BBK) triggered and distributed. Warnings are only issued for a limited period of time and in a precisely defined area. Nationwide alarms such as the test alarm on warning day were recorded in practice for the first time during the corona pandemic.

In Germany, three established warning apps are currently being launched: Nina, Katwarn and Biwapp. All three have been exchanging messages with each other since February 2019. In this way, all messages, regardless of how they got into one of the systems, reach all affected users of all three apps.

The systems behind the warning apps have interfaces through which they record warning messages directly and can process, for example from authorities and weather services. Katwarn has an editorial service that looks after these entries and supervises the system.

The warning apps are always working location-based and only send the messages specifically to those affected.

If you want to be on the safe side, you should still find out on the website of your district or city administration with which of the three warning apps it is exchanging data directly and installing this app. This increases the likelihood that warnings for the respective location will be delivered promptly and reliably.

This is exactly what made the decisive difference on the warning day: For example, anyone who was in a circle using Katwarn, and Katwarn used as a warning app, received the alarm message in the worst case with a few minutes delay. Others waited a long time for the alarm message – if it occurred at all.

Mobile networks load-proof In any case, it was not down to the cellular networks: Even if warnings are sent to numerous users within a very short time, 3G and 4G cellular cells can shoulder the necessary data volumes without any problems. It could only become tight after the successful delivery, when such startled users respond to the alarm simultaneously and in large numbers and, for example, pick up the phone or access data on the Internet.

Katwarn is a project of the public insurer, the Programming is at the Fraunhofer Institute for Open Communication Systems, in short Focus. In an interview with ct, project manager Daniel Faust explained why not all warnings were received for a long time: “Numerous municipalities are directly connected to our system. Numerous reports came in on the warning day, all of which we delivered within minutes. However, the nationwide MoWaS system handed over its Alerts only partially sent to Katwarn. That is why many users received no or late warnings, although our system was working properly. ”

” Der Failed warning day is not related to the warning app Nina ” The spokesman for the Federal Ministry of the Interior, Björn Grünwälder, confirmed that the problems were due to MoWaS. who is also responsible for the warning app Nina of the Federal Office for Civil Protection and Disaster Aid (BBK): “The failed nationwide warning day on 10. 9. 2020 is not related to the warning app Nina. ”

Problems with Nina only occurred on the first warning day 2018 in North Rhine-Westphalia. “Weaknesses in coping with load peaks” were revealed. That was fixed immediately, on the warning day, which is also still limited to NRW 2019, the app was able to handle the peak load without any problems. The app is currently used by an estimated 9.2 million users, but the capacity is sufficient for 40 million.

The warning app Biwapp processes Not only warning messages, but also service messages from the municipalities such as traffic information or school dropouts.

The reason for the current problems is a design error in the programming of MoWaS. Grünwälder explains: “According to the information provided by the service provider for the operation of the modular warning system, a high volume of simultaneous database queries from the users led to the system overload that was the cause of the delayed message processing.” After the warning from MoWaS was delayed, Nina delivered the warnings within a few seconds.

Apparently, the situation then developed a fatal momentum of its own: When those responsible in disaster control realized that their reports had not been received, Some media reported that some of them sent further messages afterwards to be on the safe side, which exacerbated the acute load problem.

Alternative to the app -The solution are cell broadcasts A stable alternative to an app solution would be cell broadcasts, as used in other EU countries, such as the Netherlands or Romania. Such messages are broadcast for all participants in a radio cell. But this only works for the current