# Weather and Operational Parameters

Limit parameters define the environmental and atmospheric conditions under which an operation can safely take place. They are used in **limit sets** to automatically evaluate weather conditions and determine whether a mission can be executed safely.

Two types of limit sets exist:

<table><thead><tr><th width="140">Limit set type</th><th>Description</th></tr></thead><tbody><tr><td><strong>Aircraft type limit set</strong></td><td>Defines the <strong>technical and physical limitations of the aircraft</strong> itself. These limits typically come from manufacturer specifications or certification documents.</td></tr><tr><td><strong>Operational limit set</strong></td><td>Defines <strong>mission-specific operational rules</strong>. These limits may come from regulations, company procedures, payload constraints, or risk assessments such as SORA.</td></tr></tbody></table>

Some parameters can be used in **both** types of limit sets, while others are only relevant for **operational rules**.

## Wind

| Parameter   | Description                                      | Aircraft type limit set | Operational limit set |
| ----------- | ------------------------------------------------ | :---------------------: | :-------------------: |
| Wind speed  | Mean wind speed over a 1 hour interval           |            ✓            |           ✓           |
| Wind gusts  | Maximum wind gusts within a 1 hour interval      |            ✓            |           ✓           |
| Gust factor | Difference between peak gust and mean wind speed |            ✓            |           ✓           |

## Temperature & Humidity

| Parameter               | Description                                              | Aircraft type limit set | Operational limit set |
| ----------------------- | -------------------------------------------------------- | :---------------------: | :-------------------: |
| Outside air temperature | Mean outside air temperature over a 1 hour interval      |            ✓            |           ✓           |
| Dew point               | Mean dew point temperature                               |            ✓            |           ✓           |
| Relative humidity       | Mean relative humidity within a 1 hour interval          |                         |           ✓           |
| Spread                  | Difference between outside air temperature and dew point |            ✓            |           ✓           |

## Clouds & Visibility

| Parameter          | Description                                                         | Aircraft type limit set | Operational limit set |
| ------------------ | ------------------------------------------------------------------- | :---------------------: | :-------------------: |
| Visibility         | Horizontal visibility at ground level                               |                         |           ✓           |
| Cloud ceiling      | Height of the lowest cloud layer covering more than half of the sky |                         |           ✓           |
| Cloud base         | Lowest altitude of the visible portion of a cloud                   |                         |           ✓           |
| Cloud cover low    | Cloud coverage between 0–2 km above ground level                    |                         |           ✓           |
| Cloud cover medium | Cloud coverage between 2–7 km above ground level                    |                         |           ✓           |
| Cloud cover high   | Cloud coverage between 7–10 km above ground level                   |                         |           ✓           |
| Cloud cover total  | Fraction of the sky covered by all clouds                           |                         |           ✓           |

## Precipitation & Snow

| Parameter            | Description                                           | Aircraft type limit set | Operational limit set |
| -------------------- | ----------------------------------------------------- | :---------------------: | :-------------------: |
| Precipitation        | Accumulated precipitation over a 1 hour interval      |            ✓            |           ✓           |
| Precipitation prob.  | Probability of precipitation during a 1 hour interval |            ✓            |           ✓           |
| Snow depth           | Depth of snow on the ground                           |            ✓            |           ✓           |
| Snowfall probability | Probability of snowfall                               |            ✓            |           ✓           |
| Fresh snow 24h       | Accumulated fresh snow within the last 24 hours       |            ✓            |           ✓           |

## Atmospheric Stability

| Parameter          | Description                                                                    | Aircraft type limit set | Operational limit set |
| ------------------ | ------------------------------------------------------------------------------ | :---------------------: | :-------------------: |
| CAPE index         | Convective Available Potential Energy index indicating atmospheric instability |            ✓            |           ✓           |
| Lifted index       | Atmospheric instability indicator based on parcel lifting                      |            ✓            |           ✓           |
| Thunderstorm prob. | Probability of thunderstorms within a 1 hour interval                          |                         |           ✓           |

## Icing & Radiation

| Parameter        | Description                                                               | Aircraft type limit set | Operational limit set |
| ---------------- | ------------------------------------------------------------------------- | :---------------------: | :-------------------: |
| General icing    | Indicator for possible icing conditions based on temperature and humidity |            ✓            |           ✓           |
| Icing potential  | Forecast probability and intensity of icing conditions                    |            ✓            |           ✓           |
| Global radiation | Total solar radiation at ground level                                     |            ✓            |           ✓           |

## Space Weather

| Parameter | Description                                                | Aircraft type limit set | Operational limit set |
| --------- | ---------------------------------------------------------- | :---------------------: | :-------------------: |
| KP index  | Geomagnetic disturbance index that may affect GNSS signals |            ✓            |           ✓           |


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