# 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 |            ✓            |           ✓           |
Limit set type	Description
Aircraft type limit set	Defines the technical and physical limitations of the aircraft itself. These limits typically come from manufacturer specifications or certification documents.
Operational limit set	Defines mission-specific operational rules. These limits may come from regulations, company procedures, payload constraints, or risk assessments such as SORA.