ances , ▁such ▁as ▁st ov es , ▁o vens , ▁furn aces ▁ ▁Sh ut ▁off ▁val ves ▁for ▁water ▁and ▁natural ▁gas ▁or ▁prop ane , ▁as ▁well ▁as ▁dis connect ▁electric ity ▁ ▁Close ▁black out ▁cur tain s ▁( plain ▁black ▁cur tain s ▁that ▁would ▁block ▁light ▁from ▁coming ▁in ▁or ▁going ▁out ). ▁This ▁step ▁was ▁changed ▁after ▁the ▁atomic ▁age ▁began : ▁where ▁white ▁cur tain s ▁were ▁used ▁to ▁reflect ▁the ▁thermal ▁flash ▁of ▁the ▁bomb , ▁black ▁cur tain s ▁were ▁used ▁in ▁World ▁War ▁II ▁to ▁prevent ▁any ▁air bor ne ▁enemies ▁from ▁seeing ▁light ▁from ▁windows ▁ ▁Get ▁to ▁a ▁public ▁shelter , ▁a ▁fall out ▁or ▁bomb ▁shelter , ▁or ▁the ▁household ▁bas ement , ▁and ▁stay ▁there ▁until ▁the ▁local ▁police ▁or ▁block ▁w arden ▁dismiss ed ▁the ▁black out . ▁ ▁Modern ▁technology ▁The ▁benefits ▁of ▁black outs ▁against ▁air ▁attack ▁are ▁now ▁largely ▁null ified ▁in ▁the ▁face ▁of ▁a ▁techn olog ically ▁s oph istic ated ▁enemy . ▁As ▁early ▁as ▁World ▁War ▁II , ▁aircraft ▁were ▁using ▁radio - be am ▁navigation ▁( see ▁" B attle ▁of ▁the ▁Be ams "), ▁and ▁targets ▁were ▁detected ▁by ▁air - to - ground ▁rad ar , ▁( e . g . ▁H 2 X ). ▁Today , ▁not ▁only ▁are ▁night - vision ▁g og g les ▁readily ▁available ▁to ▁air ▁cre ws , ▁but ▁s oph istic ated ▁satellite - based ▁and ▁in ert ial ▁navigation