Limit Set

Description of the "Aircraft type limit set" and "operational limit set".

A limit set is a collection of weather parameters that define the operational boundaries for a mission. The limit sets are the basis for the evaluation of weather parameters within NOVA Now, Aware or Cast.

There are two flavors of limit sets: Aircraft Type Limit Sets and Operational Limit Sets. They have different uses, but the same set-up process.

Limit Set Dialog

You can create or modify limit sets in the corresponding dialog from the NOVA Asset Manager.

Parameters considered in the limit set are shown on the left side of the dialog. A searchable selection of available parameters is given on the right side. You can add parameters to the limit set using the "+" button.

Limit set configuration

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Aircraft Type Limit Set

Defines operational boundaries based on the aircraft's specifications, typically from the aircraft spec sheet. These limits apply to a specific aircraft type (e.g., Airbus A320) and include hardware, weather, and performance-related factors that determine its operational capabilities.

An aircraft type limit set can be added to an aircraft type asset.

Operational Limit Set

Defines boundaries based on operational considerations, typically outlined in the Concept of Operations (ConOps). These limits specify the conditions under which an mission can be performed. While operational limit sets may include the same parameters as the aircraft type limit sets, one can be more restrictive than the other. These cases are handled by the evaluation algorithm in NOVA Now, NOVA Aware, and NOVA Cast.

An operational limit set can be added directly to a mission.

Parameter Thresholds

Each weather parameter can be given thresholds that define nominal, moderate, or severe conditions. Nominal conditions are generally safe for flying. Moderate conditions are intermediate and require further assessment. Severe conditions are those where safe flights are not possible.

The parameter limits can be set using 4 different types of limit thresholds. Thresholds with corresponding units can be set at the transitions between value ranges.

For each parameter, Unisphere provides initial suggestions for the threshold configuration. Make sure to update these values according to your aircraft specifications or concept of operations.

Parameter Altitude

For certain parameters the height at which parameters should be evaluated can also be specified.

Some parameters (e.g., wind speed) can be evaluated at various altitudes. In this case, the altitude can be defined within the limit set. Such altitude definitions are only used in local or multi-location missions. For route missions, altitude-dependent parameters are always evaluated at the flight altitude defined within the route.

You can use the same parameter multiple times e.g. to be aware for wind speeds at different altitudes.

Same parameter used two times at different heights

Flight Phases

You can define different limits for different flight phases. For example, you may want to provide stricter wind speed limits for takeoff and landing than during the cruise phase. A parameter that you add to your limit set can be added for the entire mission or specifically for each phase: takeoff, en-route, and landing by selecting the corresponding tab in the limit set dialog.

Applicable limits per phase of flight