Signal Ranges Reference
Different signaling methods have vastly different effective ranges. Understanding these helps you choose the right method for your situation and set realistic expectations for rescue.
Signal Fire (Smoke)
Daytime signal fires with green wood produce white smoke visible up to 20-30km in clear conditions from elevated positions. Darkness increases contrast, making smoke visible further. Aircraft typically spot signal fires from 5-15km in good conditions. Wet or smoky materials produce dark smoke — less visible from air but still detectable.
Signal Mirror
A standard signal mirror (3x5 inches) can produce a flash visible to the naked eye at distances exceeding 30km in clear conditions with precise aiming. The flash can be seen from aircraft at 10-20km. The key is accurate aiming — the mirror must reflect sunlight directly toward the target. In poor light or fog, mirror effectiveness drops dramatically.
Flares
Handheld parachute flares burn for 30-60 seconds at 15,000-20,000 candela. Visible from aircraft at up to 50km in clear conditions, but only a few kilometers in haze. Distress flares are visible from ground level at 5-10km in clear conditions.