Guide · Signalling

Using a signal mirror

On a sunny day, a flash from a mirror can be seen many kilometres away — often much further than a person, a fire or a bright jacket. It weighs almost nothing and needs no battery.

What you can use

• A purpose-made signal mirror with a sighting hole is best.
• Any shiny, flat surface can work: a small mirror, a phone screen, a CD, a metal lid, a polished tin or a piece of foil smoothed over card.

Aiming a mirror with a sighting hole

1. Hold the mirror close to your eye and look through the hole at your target.
2. Hold your other hand out in front, so sunlight passing through the hole makes a bright spot on your hand.
3. Slowly tilt the mirror while still looking through the hole. You'll see a bright dot of light in the sight.
4. Move the mirror until that dot sits on the aircraft, boat or person you want to reach.

Aiming any mirror: the V method

1. Stretch one arm out towards your target and make a V with two fingers, with the target sitting in the gap.
2. Hold the mirror near your face with your other hand.
3. Tilt the mirror so the reflected sunlight lands on your fingers.
4. Rock it gently so the light flashes up through the V towards the target.

How to signal

• Sweep the flash slowly back and forth across the target. This makes it easier to hit and catches the eye.
• Flash in groups of three, which is a common distress pattern.
• Keep scanning the horizon even when you can't see anyone. Pilots and walkers may notice a flash before you notice them.
• Once a pilot has clearly seen you — for example by rocking their wings, changing course or flashing lights — stop flashing directly at the cockpit, as the glare can dazzle them. Flash occasionally to help them keep track of you.

When the sun is behind you

It's harder to aim when the sun is behind you. Try standing side-on or angling your body. If the sun is very low behind you, move to a spot where you can catch it at a better angle.

Cloudy days

A mirror works best in full sun, but even weak sunlight through thin cloud can produce a visible flash. On dull days, rely on bright colours, ground signals, a whistle and a torch instead.

Keep it ready

Keep your mirror somewhere quick to reach, such as a chest pocket. Aircraft pass quickly and you may only have seconds.

This article is in the Grid Survivor app, searchable with no signal. Get the app · £4.99