NORRBOTTEN
PROTOCOL

Pre-Flight (Indoor, Heated) — Arctic Protocol

Implementation

# Norrbotten Arctic Pre-Flight Checklist
import subprocess, sys

def arctic_preflight(ambient_temp_c, kp_index):
    """Arctic-specific pre-flight checks."""
    checks = []
    
    # Battery temperature
    if ambient_temp_c < -20:
        checks.append(("BATTERY", "Pre-heat 30min required", "MANDATORY"))
    
    # Compass (aurora)
    if kp_index >= 5:
        checks.append(("COMPASS", "DISABLE — set COMPASS_USE=0", "MANDATORY"))
        subprocess.run(["mavproxy", "--cmd", "param set COMPASS_USE 0"])
    elif kp_index >= 3:
        checks.append(("COMPASS", "Monitor EKF innovations", "WARNING"))
    
    # Propellers
    checks.append(("PROPELLERS", "Carbon fiber ONLY below -15°C", 
                    "MANDATORY" if ambient_temp_c < -15 else "RECOMMENDED"))
    
    # Flight time
    endurance_factor = max(0.3, 1.0 + (ambient_temp_c * 0.02))  # -2% per °C
    checks.append(("ENDURANCE", f"Plan for {endurance_factor:.0%} of nominal", "INFO"))
    
    # Gloves
    if ambient_temp_c < -10:
        checks.append(("GLOVES", "Touch-screen gloves required", "MANDATORY"))
    
    for check, note, level in checks:
        symbol = "❌" if level == "MANDATORY" else "⚠" if level == "WARNING" else "ℹ"
        print(f"  {symbol} {check}: {note}")
    
    return all(level != "MANDATORY" for _, _, level in checks)

During Flight

Monitor battery voltage continuously. At -30°C, expect 20% less total capacity than the label says. Set RTL (Return To Launch) battery threshold 30% higher than normal: if you normally RTL at 20%, set it to 30% in arctic conditions. Fly aggressively for the first 30 seconds — the motors generate heat that warms the battery from the inside. A gentle hover in cold air is actually more dangerous than aggressive flying because the battery stays cold.

Optical flow sensors (PMW3901) may fail over uniform white snow — no visual features to track. Fallback: barometric altitude + pilot visual navigation only. Disable optical flow if readings are erratic: FLOW_TYPE=0.

The Norrbotten arctic protocol defines every step of drone operations above the Arctic Circle. Norrbotten winter conditions at minus thirty degrees require modifications to batteries, propellers, navigation, and operator equipment. The protocol is compiled from published arctic-UAS research, equipment manufacturer specifications, and public-source winter exercise reports from NATO allies — FSG-A has not yet conducted its own winter exercises at Norrbotten regiment.

Training Calendar

The Norrbotten arctic protocol requires annual revalidation: one week of winter exercises at Norrbotten regiment between January and March when temperatures reliably reach -25°C or below. Day 1-2: classroom refresher on all 15 arctic failure modes and mitigations. Day 3-4: outdoor battery pre-heating drills, compass disable procedures, carbon propeller verification, dismount drills at temperature. Day 5: full-day ISR mission with Fischer 26 in arctic conditions — measure actual endurance versus calculated, verify thermal camera performance against cold targets, test MANET relay at range with atmospheric ducting effects. Day 6-7: AAR and protocol update. Any new failure mode discovered during the exercise is documented and added to the next protocol revision.

Equipment Modifications for Arctic

Beyond procedural changes, the Norrbotten protocol specifies physical modifications to equipment. Carbon fiber propellers replace polycarbonate on all drones (€15 per set, mandatory below -15°C). Silicone conformal coating (€8, MG Chemicals 422B) applied to exposed circuit board traces on the flight controller prevents moisture intrusion during temperature cycling. XT60 connectors replaced with XT90 on Fischer 26 (lower contact resistance at high current reduces voltage sag in cold conditions). FPV camera lens anti-fog treatment (Cat Crap anti-fog paste, €5) prevents condensation on the lens during rapid temperature transitions. All modifications are performed once at the beginning of winter season and remain for the duration of arctic operations.

Documentation and Revision Process

The Norrbotten arctic protocol is a living document revised annually based on winter exercise findings. Version control follows semantic versioning: major version increments when fundamental procedures change (new equipment type, revised temperature thresholds), minor version when corrections are added (updated battery chemistry data, new supplier for carbon propellers). Every revision includes the specific finding that prompted the change, traced to the AAR record from the exercise where it was discovered. This traceability ensures the protocol remains evidence-based rather than opinion-based.

Related Chapters

Sources

Mathematically verified estimates. LiPo capacity degradation of 40–60% at −30 °C is validated in provable_claims.py under LIPO_CAPACITY_MINUS15 and LIPO_CAPACITY_MINUS20. The "−2% per °C below zero" endurance factor is a linear approximation from public LiPo datasheets over a narrow range; outside −20 °C the model degrades, and FSG-A uses discrete values in code.

Parameter sources. Kp-index and aurora forecasts — NOAA Space Weather Prediction Center. Norrbotten climate (−30 to −40 °C, 0–4 hours of light in December) — public SMHI data. Krytox GPL-205 characteristics (operating down to −60 °C) — Chemours datasheet. MG Chemicals 422B silicone coating specifications — manufacturer datasheet. Fatshark HDO3 OLED specifications — manufacturer datasheet. ArduPilot parameters (COMPASS_USE, FLOW_TYPE) — ArduPilot documentation. Magnetic deviations of up to 10° during aurora — public geomagnetic disturbance research.

Operational estimates — not validated by FSG-A in the field. The "number one cause of arctic drone loss" claim is a qualitative assessment based on public reporting of drone operation in arctic conditions, not FSG-A statistics. The "3 minutes at −30 °C vs 8 minutes warm" figures are illustrative values for typical FPV drones; actual numbers depend on platform. The €350 Fatshark HDO3 price is a 2024 retail figure. €5 plywood / €15 dedicated pad costs are market estimates. The 7-day exercise cycle is a protocol design goal, not yet tested.

External standards and references. Norrbotten climate data (SMHI). Geomagnetic Kp-index (NOAA Space Weather Prediction Center). Public reports on arctic military exercises (Cold Response, Nordic Response). ArduPilot documentation for cold-weather parameters. Public datasheets of LiPo batteries (Tattu, GNB, CNHL). FSG-A has no arctic flight data — the protocol is compiled from public sources and technical specifications.