Information Contained Within the Flight Block (sometimes Referred To As A Puk)
Subject to the vendor’s design and the airline’s specifications, the blocks themselves or the surrounding spaces contain sufficient detail to provide Controllers with basic information about a flight. The minimum information will consist of the flight number, scheduled departure time, scheduled arrival time, and passenger load (booked passengers on a flight). The system will also show the ports where the flight is operating to/ from. These may appear as additional information on the blocks themselves or more commonly, to reduce clutter, will appear between the blocks. This information may appear to be static on the block, but with the passage of time, changes occur with the progression of both normal and disrupted operations. Once a flight departs, a number of updates take place. If a flight departs on schedule, an actual departure time either
Figure 4.4 Gantt chart representing domestic or short-haul operations
Figure 4.5 Gantt chart representing flag or international operations updates the scheduled time, or appears as additional information on the block, and (subject to the software) the block or part thereof may change to ‘green’. If the flight were delayed, say 15 minutes, an additional notation such as a +15 may appear on the block. Delays anticipated, or lack of departure information may be represented by an alert colour such as ‘orange’, while a ‘red’ colour may be triggered by a further delay over a certain time. Such display changes are unique to the software and/or airline preference, and accordingly may vary.
Should a flight depart on time, but the estimated arrival time exceed or otherwise differ from the scheduled arrival time, the block may also signify this with a coloured or additional piece of information. Similarly, should an aircraft return to blocks or divert to an airport other than the scheduled destination, the Gantt chart will reflect this activity. Routinely, these changes are automatically updated on the displays either by an aircraft’s messaging system (such as ACARS), or by a port-generated message source, giving the Controller real-time information and reflecting the most accurate condition of flights under watch. However, Controllers also have the ability to alter details manually as the need arises. For example, should a Controller become aware of a delay due to a known maintenance issue, an estimated time of departure can be set for the flight, at which time the flight block concerned, and potentially others, will be updated. Controllers will also alter flight block information should more substantial changes be evident, such as the need to show a flight diversion, cancellation or other event. Figure 4.6 shows an example of the standard information contained on a flight block.
Information Contained (explicitly) in the Gantt chart
One of the competing dilemmas in Gantt displays is, on the one hand, the need to provide as much information as possible to facilitate the task, while, on the other hand, the need to simplify the presentation to the user due to the volume of aircraft and flights needing to be displayed on screen together. Despite this, an extensive amount of complementary
Figure 4.6 Information on a flight block (PUK) information is available. Some of this is explicit (i.e., evident without the need to search). As explained, the flight schedules form the key display but, of course, the space between flight blocks is important as this indicates the times where an aircraft is on the ground. Ground time may range anywhere from the shortest scheduled turnaround time provided by the Scheduling function for the specific aircraft in a specific port (perhaps even down to 15 minutes in some cases), to far longer, where an aircraft may be uncommitted for several hours or more. The significance of these ground times or gaps in the utilisation, seen as blank or white spaces on the Gantt chart, are readily sought after by Controllers, as uncommitted aircraft can provide a valuable source of capability should disruptions occur. The gaps may provide suitable buffers where late-running schedules can be recovered due to the longer ground time, or they may expose opportunities to swap aircraft patterns as one method for containing delays or solving some other problem. Should a minimum turnaround time be compromised (e.g., as a result of a delayed arrival), an alert may be triggered indicating some intervention is necessary.
Another important feature contained in the display is the inclusion of maintenance information. This information can be represented in a number of ways. Should a requirement be for a significant duration, such as maintenance work (e.g., an aircraft wash), a maintenance service (e.g., Check A), or a component change (e.g., an engine, windscreen, carpet), the representation on the Gantt chart is often a long, coloured placard stretching across the day or night, often in a distinguishing ‘red’ or ‘purple’ colour, to avoid similarity with flight blocks, as shown in Figure 4.7.
Maintenance work of a shorter duration may be represented by a smaller placard, again coloured distinctively, and often evidenced by a small icon. Alerts and violation warnings also appear as Maintenance icons, denoting perhaps checks to be performed or time-critical inspections to be carried out, as seen in Figure 4.8.