Who is this article for?

Users managing GIS layers and blocks.

Access to the GIS layers tab is required.

The feature manager contains the GIS Layers tab, which allows you to control all elements associated with OPAS functionality, including airport polygon maps and block statistics.

1. Understanding GIS layers and block data

OPAS requires a detailed polygon map of the airport, specifically all areas where aircraft land, taxi, depart and embark/disembark. Once the polygon is established, it is broken into many discrete blocks and data can be collected about aircraft transiting the blocks and the time spent in each.

This block data is different from the segment data, which identifies taxi phases of aircraft. The calculated block data allows for processing and viewing Block Statistics, and the metrics can be summarised in various ways.

The GIS layer for the airport is enabled by default in the GIS Layers tab. Generally it will be called 'Airport Blocks'. Other map objects can be controlled here also.

Note: Block statistic calculation is a processor-intensive task as it occurs client-side for each new dataset loaded. By default the functionality is disabled in the Tools > Options > General panel. Statistics are calculated for each new dataset loaded into the browser.

2. Enabling block statistics

To enable block statistics, follow these steps:

1. Go to the Tools menu.
2. Select Options.
3. On the General panel, locate the checkbox at the bottom to enable/disable the functionality.

Important: If the client PC is seeing noticeable performance issues, it is suggested the functionality be disabled.

3. Using layer controls

The Airport Blocks layer should be enabled by default. It is a critical component of the OPAS system. Be aware that the polygon layer is quite detailed and may not immediately appear on starting up the OPAS client.

The GIS Layers tab controls the appearance of any element that is related to OPAS functionality and also will open the Style Editor where visual appearance and counts can be modified.

To control layer visibility and display options:

• Click the 'eyeball' icon to make the feature visible/not visible on the map
• Click the 'legend' icon to make the map legend visible/not visible
• Click the 'A-z' icon to show/hide layer annotations on the map
• Use the dropdown menu to select how the element is displayed

4. Configuring block styles

The Style column holds a dropdown selection menu to choose how the block colouring is displayed. Each of the statistics are calculated from the current operation data in the Ops and Segment browsers. Block Statistics must be enabled from the Options panel. Limits and ranges are recalculated every time a new dataset is loaded.

There are metrics for both 'overall' and Replay states. This is because the count ranges for replay must be assessed in a different way and greatly reduced for more meaningful review.

A block that will be coloured red after 50 operations cross it for the whole day will not turn red on a replay with the same count limit. It is more meaningful to colour it red if, for example, five operations cross it in a five-minute period. This is why the Styles have been duplicated into Replay and non-Replay metrics.

Note: The thresholds for styles are not configurable, and will actively alter depending on the current dataset in the browser. Future OPAS enhancements may give you the ability to configure them.

5. Understanding block style metrics

Average Stationary Duration: OPAS assesses all the currently loaded stationary sections in any block and colours them by duration in seconds. Blocks with no stationary sections will remain the default colour. For example, a block may be coloured red if average stationary time exceeded 60 seconds.

Average Time in Block: This statistic counts the entire time operations spent in a block, both stationary and moving, and displays an average time in seconds. This should colour more blocks than the previous setting. It will also highlight unused blocks for the time period selected. For example, a block may be coloured red if average time exceeded 120 seconds.

Total MLW (Maximum Landing Weight): This statistic retrieves the Maximum Landing Weight from each Operation's registry data and sums it to result in a total weight in kilograms. This shows how much weight has 'rolled across' each block for the period selected in the browser. It is potentially a useful metric for determining wear and tear on the ground surfaces at the airport.

Note: Not all aircraft will have MLW listed in their registry entry and these statistics cannot be relied on for complete accuracy unless you are confident that registry data is comprehensive or complete. The calculation is only as good as the source data.

Total MTOW (Maximum Take Off Weight): This metric is similar to the previous, where MTOW is retrieved from each Operation's registry entry, and the total is summed to provide a weight in kilograms that 'passed over' each zone for the period selected in the browser. It may be used to indicate overall wear and tear on airport surfaces and can validate decisions on replacement or refurbishment. It is dependent on the registry data actually containing an MTOW entry for each operation, so may not be completely accurate.

Transit Count: This metric sums transits through the block for the period selected. It is simply a count for how many aircraft passed through. It would be expected that most runways would be red, as well as busy taxiways. It is a straightforward metric that shows areas of high and low traffic and could be used to identify congested areas.

Unknown MLW: This metric is a count for operations that crossed a block where no Maximum Landing Weight was found in the registry for that operation.

Unknown MTOW: This metric is a count for operations that crossed a block where no Maximum Take Off Weight was found in the registry for that operation.

Replay Styles: Each of the styles has been duplicated as a Replay version for reasons stated above. The counts and ranges will be lowered so as to show a more meaningful replay.

For each Style chosen, if the map legend is enabled, the legend will change to reflect the style currently on display.

The Operational Segments style can also be changed here; descriptions of the styles have been covered in a previous section.