Our eyes and ears can provide some basic useful lightning ranging information. These common sense detectors should not be ignored, especially under field conditions. However, relying on them exclusively in an explosives environment is not recommended. Count the time in seconds from seeing lightning's flash to hearing the associated thunder or bang. For each five seconds, lightning is about one mile away.
Thunder is heard from the associated lightning when it is within our audible range.
That acoustic distance can extend beyond 6 miles. When thunder is heard, a heightened lightning safety status should be enacted. However, explosives or volatile fuels operations, for example, may require more time for operations shutdown. We recommend waiting to resume activities for 30 minutes after the last observed lightning or thunder. A LWS by itself does not constitute satisfactory lightning protection, however, it is very useful as a part of an overall safety plan dealing with the lightning hazard.