# The lights exist for someone just passing through > Obstruction lights on a radio mast are aimed entirely at pilots passing overhead — a warning kept lit all night for an audience the people maintaining it don't meet. August 19, 2026 · https://justog.club/stories/radio-mast-warning-lights A radio mast, barely there — a faint dark lattice against black. Up its height, five red lights sit at even spacing, the topmost a little larger than the rest. Nothing else in the frame is lit. The mast isn't really the subject. The lights are, because they're the one part of this structure built to be seen by anyone at all. ## What's actually printed on this shirt? Five obstruction lights and the faint outline of the mast that carries them, with nothing brighter than the lights themselves. The mast is drawn dark against dark deliberately — a lattice structure is mostly air, and from any distance it disappears into the sky behind it long before the lights do. Evenly spaced up the height and one size larger at the top, the five lights are doing the actual communicating; the structure is just what they're bolted to. ## Why are the lights aimed at the sky and not at anyone on the ground? Because obstruction lighting exists for aircraft, and a mast tall enough to need it is usually well clear of anyone at ground level to warn. The lights mark the structure's height and outline for a pilot who might otherwise fly into it in poor visibility or after dark — spaced evenly up the shaft so the whole silhouette registers rather than just its base, with a larger light at the top because the summit is the point that has to clear a flight path. Nobody on the road below the mast is the intended audience; the design is aimed upward, at somebody just passing through, not based here. ## What makes a good print of an obstruction light, rather than just a red dot? Letting the mast stay nearly invisible so the lights do all the visual work, the way they actually do at night. A version that drew the mast in full, bright detail would be showing something a real observer mostly doesn't see after dark — the lattice work is picked out by daylight, not by the lighting system, so keeping it as a faint trace and putting all the ink's weight into the five red points matches what the structure is actually doing between dusk and dawn. ## Can I put a real broadcaster's name or a specific mast's location on this? Yes, with the broadcaster's or site owner's permission — the mast shape and the lighting pattern belong to nobody. A lattice structure with evenly spaced obstruction lighting describes a widely used design, free to draw the way any generic structure is. A specific transmitter's call sign, a named broadcaster's branding, or an exact grid reference identifies a real, working site, and using any of those is a permission worth having if a particular mast is genuinely what the shirt is about. ## Does the "lit for strangers" idea work for something other than a radio mast? Yes — anything whose signal is built entirely for people passing through, rather than for anyone local, tells the same story. [A lighthouse's characteristic — its particular pattern of flashes — exists to be read by a ship unlikely to come this way again](/stories/lighthouse-characteristic), and [a shipping forecast is broadcast for boats out on the water rather than for anyone listening at home](/stories/shipping-forecast-areas). Different mechanisms, the same audience: whoever's just passing through, once. ## Isn't a mast that's barely visible a strange thing to put on a shirt? No — the near-invisibility is accurate, and it's what makes the five lights the actual subject. A mast drawn in full would be a picture of a structure; a mast drawn faint, with just its lights showing clearly, is a picture of what the structure is actually for after dark, which is the more honest and more specific image. Losing the lattice to the black is the print doing the same thing the night does. ## Does it print well? Yes — one deep red on near-black is a high-contrast, low-detail combination that holds up small. Five flat points of colour, evenly spaced, survive the fabric far better than any gradient glow or a lens flare around each light, and near-black lets the faint mast lines sit at just enough contrast to register without competing with the red. One ink is enough; the lights don't need to look like they're shining — just that they're on. ## How do I get one made? Describe your own structure and its lights at [JustOG](/) — how many, how spaced, how faint the frame around them stays. Pick a direction, drag the crop frame, see it composited on the real garment, and it's made to order and shipped. Designs other people have published are in the [shop](/shop). Five red lights, evenly spaced, still on at four in the morning for a pilot who isn't from round here.