Why air raid sirens are sounding again, from Mumbai to Jaisalmer

The sirens in Mumbai, Jaisalmer and Bihar were sounded as planned tests of air raid warning equipment. Mumbai’s civic body specifically told residents not to panic or misunderstand the sound. There was no actual emergency or threat behind the demonstrations.

The tests took place in stages. Jaisalmer held one on September 30, Bihar followed on October 6, and Mumbai sounded sirens in the Fort area on October 8 and 9. Mumbai’s Old Secretariat building hosted the operational trial and field testing.

These demonstrations are part of a broader effort to create one national warning system. Officials are checking sound range, duration, connectivity and local conditions. The goal is to replace inconsistent systems with centrally triggered sirens that can be activated by a targeted cell broadcast message.

An air raid warning siren is a loud public alert used to warn people that an attack or other serious emergency may require attention. The article places it within India’s Civil Defence system. Its purpose is to communicate danger quickly, especially when people may need to respond to an air attack or emergency situation.

The sirens were central to nationwide civil defence mock drills ordered after Operation Sindoor. They were also tested in places including Jaisalmer, Bihar and Mumbai. During those trials, officials listened to the sound and recorded how far it travelled and how long it continued.

The warning system is being modernised because many older sirens had stopped working. The proposed replacement would allow officials to activate sirens from one central system. Geo-fencing could limit the warning to a specific area, rather than sounding sirens across an entire state or country.

India’s recent warning-system effort operated at both national and local scales. On May 7, the Union Home Ministry ordered civil defence mock drills in 244 districts. It was the first nationwide exercise of its kind in decades, and air raid sirens were central to the drills.

Separate equipment trials began in border states such as Rajasthan. Jaisalmer tested its system on September 30, Bihar held a test on October 6, and Mumbai conducted trials in the Fort area on October 8 and 9. Officials also tested the prototype at Mumbai’s Old Secretariat Annexe Building.

The travelling team has now moved from border areas to coastal states such as Maharashtra. Punjab is likely to be tested next month. At each location, officials examine sound range, duration, connectivity, noise type and local needs before finalising a common system.

India began seeking a standardised siren system after Operation Sindoor revealed serious gaps in local warning equipment. During the May 2025 hostilities, Pakistan responded to India’s strikes with drone and missile attacks on border areas. Air raid sirens became central to civil defence drills and public fear of possible attacks.

Many states had stopped using sirens, so older equipment no longer worked. When the threat appeared, states rushed to buy replacements. An official from Maharashtra said they purchased sirens without common specifications, often buying whatever equipment was available.

After the immediate urgency passed, officials focused on uniformity. They wanted a prototype that could define specifications for future purchases. A common system could also support central triggering and geo-targeted alerts, while still allowing local factors, such as Mumbai’s skyscrapers, to shape final installation decisions.

The proposed system uses cell broadcast technology developed by the Centre for Development of Telematics, or C-DOT. A central authority sends a cell broadcast message instead of relying on someone at each siren location to operate it manually. The message acts as the remote trigger.

Geo-fencing supplies the location control. Officials define a particular geographic area, and the system directs the activation only to sirens within that boundary. This means a warning could be limited to one area instead of reaching an entire state or the whole country.

The method was demonstrated during field testing at Mumbai’s Old Secretariat Annexe Building. C-DOT activated the siren multiple times through cell broadcast messages. The trial showed real-time, centralised and geo-targeted dissemination, but the system remains a prototype under testing before final specifications are set.

The Centre for Development of Telematics, or C-DOT, is leading the effort under the Department of Telecommunications. It is working with the Director General, Civil Defence, New Delhi. Civil Defence officials are travelling with the team to observe trials across the country.

The trials began in border states such as Rajasthan and moved to coastal Maharashtra. Officials tested the system in places including Jaisalmer, Bihar and Mumbai. At Mumbai’s Old Secretariat Annexe Building, C-DOT demonstrated centralised, real-time and geo-targeted siren activation through cell broadcast messages.

Observers record how far the sound carries and how long the siren runs. They also examine technical connectivity and the type of noise it produces. Local conditions and installation needs matter too. In Mumbai, for example, skyscrapers can block sound from a siren placed on a lower floor. These observations may lead to prototype changes.

A siren becomes less effective when its sound cannot travel clearly to the people it is meant to warn. Distance, surrounding noise and local geography can affect how well the warning reaches an area. The article says officials are measuring these conditions during trials rather than assuming one arrangement will work everywhere.

Mumbai provides the clearest example. The city has many skyscrapers, and an official said a siren on the third floor may be ineffective because adjacent buildings could block the sound. A warning might therefore fail to reach nearby streets or buildings as intended.

Officials are recording sound range, duration and the type of noise produced. They are also considering each state or city’s unique conditions. The final system may use common technical standards, but installation and placement will need local decisions so warnings remain audible and useful.