Wildfire front observation and crew connectivity.

The mission

A forest fire in hill country. A drone with a thermal camera orbits the front, and its picture is the operation’s single most valuable object: where the line actually is, where it is jumping, which crew is about to have the wind turn on them. The staff sits at a vehicle on a forest road; hose crews and dozer teams work below; an aerial coordinator wants the same feed. The front does not hold still, and neither does anything else.

What breaks

Mountain forest is the textbook coverage void — the villages have cells, the ridgelines and drainages between them do not. Crews a kilometre apart lose each other behind a spur; the staff loses the crews as they advance; and the classical answer, handheld radio relayed by shouting distance and repetition, carries voice but never the picture. When the picture does flow, a second failure appears: three stations watching the same thermal feed classically means three copies on the aircraft’s downlink — the scarcest hop pays the multiplied bill. And the aircraft that provides everything must land to swap batteries every half hour, taking the network down with it unless the swap is engineered.

The architecture on this mission

The aircraft runs a node, and so do the staff vehicle, the crew kits and the coordinator’s station: one mesh, formed on their own radios, owing nothing to the burned-over infrastructure. The aircraft’s orbit gives it line of sight into drainages no ground station has, so crew traffic — positions, voice, orders — routes through it; the class system ranks those above the video, so a narrowing hop thins the picture before it ever touches a position report.

The thermal feed itself uses subscriber-aware multicast: the staff, the coordinator and a sector chief subscribe, and the mesh computes a distribution tree so the shared hops — starting with the aircraft’s own downlink — carry exactly one copy per packet, with copies made only where the watchers’ paths part. Measured on an eight-node rig: five minutes of Full-HD-rate video to three stations, the scarce first hop carrying one copy. A feed nobody subscribes to costs nothing.

The battery swap is a routing event, not an outage: the relief aircraft joins the mesh on climb-out, and when the first aircraft departs, routes re-form on the new topology — self-healing on lost-node detection is roughly a second and a quarter at default settings. Detections and crew status generated during any gap queue store-carry-forward and deliver on reconnection, in priority order.

How the deployment unfolds

1. On scene. The staff vehicle parks on the forest road, the observation aircraft launches, and the crew kits join as the teams deploy — one mesh, formed on the service’s own radios, owing nothing to the burned-over infrastructure.
2. The picture flows. The aircraft settles into its thermal orbit. The staff, the aerial coordinator and a sector chief subscribe to the feed; the mesh computes the distribution tree and the aircraft’s scarce downlink carries exactly one copy.
3. The wind turns. The front jumps a drainage and the crews advance behind a spur that cuts them off from the staff. Their traffic re-routes through the aircraft above them without anyone touching anything — positions, voice and orders ranked ahead of the video.
4. The narrow minute. Smoke and terrain thin a hop. Ordered degradation engages: the thermal picture sheds quality, position reports do not contend, and events generated in any momentary gap queue store-carry-forward and deliver on reconnection.
5. The swap. Half an hour in, the relief aircraft joins the mesh on climb-out and the first one departs to change batteries. Routes re-form on the new topology in about a second and a quarter — a routing event, not an outage.
6. The debrief. The event journal holds the operation’s communications record — who was reachable, when, over what — for the after-action review and the next deployment’s planning.

What each mechanism contributes

• The aircraft as a mesh node — observation platform and relay in one airframe; crews reach the staff through the thing already flying above them. Shipped.
• Subscriber-aware multicast trees — many watchers, one copy on the scarce hops; the tree re-forms as the fleet moves. Shipped, opt-in.
• Class-ordered degradation — positions and orders before pictures, enforced by reserved floors. Shipped, opt-in.
• Self-healing mesh and store-carry-forward — relief swaps and momentary shadowing become delays, not losses. Shipped.

The honest boundary: Atlas contributes the network. The aircraft, their endurance, the crews and the firefighting doctrine are the service’s — and heat, smoke and terrain do to radio what physics says they do; the mechanisms provide alternative paths and a strict order of sacrifice, not immunity.

What a pilot should prove

• Crew-to-staff connectivity through the aircraft across defined dead drainages where the direct path measurably fails.
• Multicast economics: the thermal feed to three watchers with the aircraft’s downlink carrying one copy, from the built-in per-link counters.
• The swap drill: a relief aircraft rotation mid-scenario with the picture and crew links re-forming without operator action.
• A full event journal of the exercise — who was reachable, when, over what — as the after-action communications record.

An exercise burn or a training deployment is the right venue. The evaluation format covers the structure.