What does the Flash-to-Bang method determine?

• A. Time of day
• B. Wind direction
• C. Distance to an explosion or enemy fire
• D. Terrain type

Answer: (C)

This method estimates how far away an explosion or enemy fire is by using the delay between seeing the flash and hearing the sound. Light arrives essentially instantly, while sound travels through air at about 343 meters per second under typical conditions. So, the time you count between the flash and the bang, multiplied by that speed of sound, gives you the distance to the source. For example, a 3-second delay corresponds to roughly 1,000 meters (about 0.6 miles). A handy rule of thumb is about 5 seconds per mile. Remember that temperature, wind, humidity, and terrain can affect sound travel, so the estimate isn’t exact. This method is specifically about locating how far away the event is, not about time of day, wind direction, or terrain type.