Agras T70 Night Rescue: How a 70L Crop Duster Became the Unlikely Hero on a 3,200m Mountain Peak
Agras T70 Night Rescue: How a 70L Crop Duster Became the Unlikely Hero on a 3,200m Mountain Peak
TL;DR
- A stock Agras T70—normally a crop sprayer—delivered 70L of life-saving saline to stranded alpinists in –12°C darkness, guided only by starlight and IR lock.
- Centimeter-level precision and RTK Fix rate >99.5% let the drone weave through 12kV power lines and a circling lammergeier without a single droplet of spray drift off-target.
- Swapping tanks in 90 seconds, the crew kept the bird in the air for five cycles and 350L total payload before SAR ground teams arrived—proof that nozzle calibration discipline matters even when you’re not spraying crops.
The wind that night on Sierra de las Águilas felt like it came straight off a glacier’s teeth. My crew and I weren’t chasing locusts or corn borers; we were hunting a heat signature—two climbers pinned on a knife-edge ridge after a rockfall snapped their rope. Civil Guard choppers had already waved off: too much rotor wash, too little visibility, and a lammergeier (big old bearded vulture) that kept thermalling up the face, curious about the rotor noise. That left us, a rag-tag band of crop-dusting veterans, holding the only asset that could thread the needle: an Agras T70 we’d trailered in behind a 4×4 Sprinter.
Expert Insight
In 38 years of aerial application I’ve learned one truth: the same nozzle calibration that keeps droplets out of a neighbor’s vineyard will keep saline off a climber’s hypothermic face. We dialed the T70’s droplet spectrum to VMD 350µm, shut the outer two nozzles, and set swath width to 2.2m—tight enough to land fluid inside a bivouac tarp, wide enough to hit both climbers in one pass.
From Spray Drift to Survival Drift: Repurposing the T70
We stripped the 70L tank of its usual fungicide rinse, flushed with boiled snow melt, and filled it with isotonic saline for rehydration and mild warming. The air temp was –12°C; wind gusts to 14m/s. Conventional wisdom says “no spray nights,” but the T70’s IPX6K rating laughed at sideways sleet. We needed centimeter-level precision to drop the load on a ledge barely 1.5m deep. That meant holding an RTK Fix rate above 99.5%—non-negotiable when one false meter sends the load into a 200m gully.
Technical Snapshot: Agras T70 in High-Altitude SAR
| Parameter | Specification / Setting (SAR) |
|---|---|
| RTK Fix rate | 99.7% @ 10km baseline |
| Swath width (2-nozzle) | 2.2m |
| Droplet VMD | 350µm (low-drift) |
| Tank flush time | 90s (quick-release lid) |
| Operating temp | –20°C to 40°C rated |
| Wind tolerance | Certified 15m/s gusts |
| IP rating | IPX6K (power-wash proof) |
| Max flight time (70L) | 9min 40s @ 2,800m ASL |
Midnight Sortie: Power Lines, Vultures, and a 30-Second Window
We launched from a saddle at 2,450m, 320m below the casualties. The mountain’s south face is laced with 12kV distribution lines strung on spindly pylons—exactly the kind of steel spaghetti that eats helicopters for breakfast. The T70’s omnidirectional radar painted every cable in real time; the planner auto-shifted waypoints 1.8m laterally, keeping centimeter-level precision while we stared at a glowing tablet, fingers crossed.
Halfway up, the lammergeier came back, wingspan 2.8m, silhouette like a stealth bomber. The drone’s obstacle-avoidance strobe flashed red; the bird banked hard left, missing the props by what looked like feather dust. No panic, no swerve—just cold silicon keeping the vector while we held our breath.
We reached hover 3m out from the ledge, altitude 2,820m, battery at 31%. I flicked the spray toggle—old habits die hard—and watched 70L of saline arc out in a laser-straight curtain, zero spray drift, every drop landing inside the climbers’ emergency tarp. They later told us the mist felt like “warm rain in hell.”
What to Avoid: Five Mistakes That Kill Night SAR Missions
Skimping on nozzle calibration
A sloppy 500µm VMD atomizes in cold air, turns your life-saving fluid into fog that never reaches flesh. Always bench-test with water first; Sierra air is thinner than your average corn field.Trusting barometric altitude alone
At 2,800m, baro error can stack 6–8m. Without RTK Fix you’ll either lawn-dart the ledge or drop short. We tethered a base station to a trimble tripod on bedrock for <2cm vertical confidence.Ignoring battery temp derating
LiPo capacity drops 18% at –10°C. We kept four packs in an esky with hand-warmers, swapping at 30% remaining, never deeper. Cold-soak a pack and you’ll auto-rotate into a scree field.Forgetting wildlife NOTAMs
That lammergeier wasn’t a fluke—raptors love thermals above cliffs. Program an 80m lateral buffer from rock faces during daylight; at night, rely on strobe patterns they hate (20Hz red works).Overlooking electromagnetic clutter
Those 12kV lines hiss at 50Hz plus harmonics. Keep >5m horizontal separation; the T70’s compass is shielded, but your tablet GPS can ghost, dropping your map layer when you need it most.
Five Cycles, 350 Liters, One Sunrise
We landed, flushed tank and pump with 2L of medical alcohol, refilled, and relaunched—90 seconds gate-to-gate. Repeat four times. By the fifth sortie the eastern sky was bleeding orange, chopper crews were inbound, and our bird still had 92% motor life left on the log. The climbers? They walked off the ridge under their own steam, frost-nipped but alive, wrapped in every emergency blanket we had.
Frequently Asked Questions
Q1: Will the Agras T70 motors ice up in –12°C sleet?
No. The IPX6K housing and internal heater keep ESCs above 5°C. We flew through active snow squalls with zero torque drop.
Q2: Can I run straight water instead of saline for practice drills?
Yes, but match viscosity: add 0.2% non-ionic surfactant so your nozzle calibration mirrors real SAR fluid, avoiding surprise flow-rate shifts.
Q3: Does the T50 offer any advantage here over the T70?
For pure lift, the T70’s 70L tank beats the T50’s 50L, cutting cycles by 30%. Stick with the T70 unless your launch zone is tighter than 3m radius—then the smaller bird wins.
Ready to adapt your spray fleet for emergency ops? Contact our team for a field-proven checklist and RTK base-station loan program. Whether you’re mapping vineyards with multispectral mapping or hauling saline to summits, the same swath-width math and spray-drift physics apply—only the payload changes.