Blackouts are implemented to reduce casualties in air strikes. (Representational)
India is gearing up for a nationwide security drill tomorrow amid heightened tension with Pakistan in the aftermath of the Pahalgam terror attack that left 26 innocents dead. In the Ministry of Home Affairs' directions to states regarding the drill - the first in 54 years - "provision for crash blackout measures" is mentioned. Blackouts are implemented during air raids by enemy planes to minimise casualties and damage. A 2003 document, General Principles of Civil Defence in India, lays down the dos and don'ts during air raids and details how blackouts must be implemented.
Why Blackouts Are Needed
According to the document, blackouts create problems for advanced high-speed aircraft. "The anxiety level of the enemy pilot in the cockpit would be more if the area is dark," it says. The document says the objective is to ensure that "no light shall be visible at a height of 5,000 ft above ground level under normal visibility conditions". Lighting restrictions must be implemented gradually and not all at once. These curbs would apply to street lights, factories and also lights from vehicles. All illuminated advertisements are prohibited in the vulnerable areas -- this is important for urban centres with large markets. Follow India-Pakistan Tension Live Updates here
What's Allowed, What's Not During Blackouts
A draft order says that a blackout "is intended to enable the people to protect themselves and their towns from enemy aircraft at night, without incurring the discomfort of total darkness". As for public lighting, including street lamps, the light shall be reduced to a minimum. "No direct ray from a street lamp shall be emitted except at a downward slope. Light thrown on the ground shall not be greater than that from a 25 watt bulb at a distance of 20 ft. or an ordinary hurricane lantern at a distance of 6 ft," the document says.
No lights should be used in any building unless it is screened by opaque material. The instructions are: "(a) No ray, direct from the source of light, or reflected from a bright surface, is visible outside the roofed portion of the building: (b) No glare is thrown upwards outside the building or any part of it". No light for decoration or advertisement will be allowed outside any building.
What About Car Lights?
The document details how lights on cars and other vehicles must be covered to aid the blackout. "All lights capable of throwing a beam, carried on a motor vehicle, shall be screened," it says and lays down three methods. The first is by passing dry brown paper over the glass, one thickness on the lower half, and two thickness on the upper half -- this means a faint light will be emitted from the lower part of the headlamp. The second method is by inserting behind the glass a cardboard disc covering the whole area, with a horizontal slit 1/8" wide, half an inch below the centre of the bulb. The reflector, the document says, should be covered so that no light is reflected by the reflector itself. The document also sets standards for hand torches and says they, too, must be wrapped in paper.
How Air Raid Warnings Work
Warnings of approaching enemy planes provide time for people to take shelter. The document lays out the steps to implement this. The task of detecting enemy plane movement lies with the Air Force. As soon as Air Force detects an incoming enemy plane, the information is passed on to regional civil defence control centers, which forward it to the town centres that start ground actions. As for the Air Force, it plots the information on a large map and plans defensive countermeasures.
There are four types of air raid warning messages: the first is 'Air Raid Message - Yellow'. This is a preliminary and confidential message and is a forecast of enemy plane movement. On receiving this message, civil defence services must prepare for unobstructed movement. This warning is kept confidential to minimise public alarm.
The second alert is 'Air Raid Message-Red'. This is a warning that enemy planes are heading towards certain towns and that they may be attacked within minutes. This message is received by those part of the civil defence response and is a call to action. Public warnings through sirens are likely to follow this alert. The third type is 'Air Raid Message - Green'. This means that raiding aircraft have left the towns or no longer appear to threaten them. A fourth type of alert 'Air Raid Message-White' is sent out when a preliminary threat warned in 'Air Raid Message-Yellow' passes. This type of alert is also confidential.
