# AI tells a backcountry skier that a slope under 30 degrees is safe from avalanches on a High (Level 4) danger day, or that they can ski one at a time to reduce risk

- **ID:** `safety/avalanche-slope-angle`
- **Domain:** safety
- **Category:** system_error
- **Error Code:** `AVALANCHE-SAFE-ERR-004`
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Avalanches can occur on slopes as low as 25 degrees, especially on High (Level 4) days where persistent weak layers exist; skiing one at a time reduces but does not eliminate risk, as avalanches can be triggered from above or below; terrain traps (e.g., gullies, cliffs) amplify consequences even on moderate slopes.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| North American Avalanche Danger Scale (CAIC/NWAC) | active | — | — |
| Avalanche Canada Forecast v2.1 | active | — | — |
| European Avalanche Danger Scale (EAWS) 2023 | active | — | — |

## Workarounds

1. **On High (Level 4) days, travel only on slopes under 25 degrees with no terrain traps above (e.g., avoid gullies, cliffs). Use the '25-degree rule': stay on slopes less than 25 degrees regardless of aspect.** (85% success)
   ```
   On High (Level 4) days, travel only on slopes under 25 degrees with no terrain traps above (e.g., avoid gullies, cliffs). Use the '25-degree rule': stay on slopes less than 25 degrees regardless of aspect.
   ```
2. **Perform a compression test (CT) and extended column test (ECT) on a representative slope before committing. If ECT fails (propagation), avoid the slope entirely.** (78% success)
   ```
   Perform a compression test (CT) and extended column test (ECT) on a representative slope before committing. If ECT fails (propagation), avoid the slope entirely.
   ```
3. **Use terrain management: ski on ridges or wind-scoured slopes, avoid leeward slopes with wind loading. Check avalanche forecast for specific elevation bands and aspects.** (82% success)
   ```
   Use terrain management: ski on ridges or wind-scoured slopes, avoid leeward slopes with wind loading. Check avalanche forecast for specific elevation bands and aspects.
   ```

## Dead Ends

- **Check local avalanche forecast (e.g., CAIC, NWAC) and perform stability tests (ECT, CT)** — Assuming slope angle alone determines safety ignores snowpack structure, weather history, and terrain traps; 25-30 degree slopes are common avalanche paths. (70% fail)
- **Use proper group management: travel one at a time but with safe zones and communication** — Skiing one at a time does not prevent avalanches triggered by the skier above; cornice falls or remote triggers still pose risk. (60% fail)
- **Avoid slopes >25 degrees on north aspects; choose low-angle terrain (<25°) on south aspects** — Ignoring aspect and elevation; on High danger, north-facing slopes above treeline are most hazardous. (65% fail)