Schedules

Introduction

A schedule is a description of a series of discrete time periods, which occur within the overall validity time of an Event. Some examples of schedules are:

• daily from 09:00 to 17:00;
• every Monday from 13:00 to sunset;
• every week from Friday 17:00 till Monday 07:00;
• etc.

AIXM supports the encoding of schedules that contain both repetitive time periods and occasional occurrences. The coding guidelines for the ICAO Data Sets include general coding rules for Schedules [PWS]. These are also applicable to Digital NOTAM Events. However, more restrictive rules apply to NOTAM schedules, such as excluding the possibility to use 'HOL' and other special dates. These limitations lead to a smaller number of coding patterns for Digital NOTAM Event schedules, which are presented in this section.

Limitations

Supported schedules

There are three types of schedules supported for Digital NOTAM Events:

• daily schedules;
  e.g. "daily from 09:00 to 17:00";
• date based schedules, including "on date" and "date range" options;
  e.g. "1/10 09:00-15:00 and on 3/10 10:00-12:00";
• days of the week based schedules, including "on weekday", or "from weekday...to weekday" options;
  e.g. "every Monday from 13:00 to sunset".

Not supported schedules

Combining different schedule types in a single NOTAM is forbidden. It is considered that such combined schedules could become too complex for being understood and would have a high potential for providing conflicting information. For example, "daily 0900-1700 and each MON 1900-2300" would not have a clear meaning. Is the schedule for Mondays just 1900-2300, or is it both 0900-1700 and 1900-2300? Therefore, such combined schedules are not supported.

Note that the concept of "weekday ranges" (such as "MON-WED") is also not supported in this specification. However, the automatic NOTAM generation rules for item D ensure that a set of consecutive weekdays with a similar start/end time will generate a "weekday range", according to the OPADD recommendations. This does not exclude implementing an HMI that allows the input of weekday ranges, for efficiency reasons. They will have to be converted into individual weekday records in AIXM.

In addition, according to the OPADD, item D is not allowed to exceed 200 characters. The application interface should check the length of the item D that results from the schedule encoding and invite the operator to split the NOTAM into two separate events in case this limit is exceeded. The HMI should allow copying a draft event into a second draft event.

UML class diagrams representation

The limitations identified above correspond to a subset of the general AIXM model for schedules. In the following diagram, classes and properties highlighted with orange color identify the part of the AIXM UML model which may be used for Digital NOTAM coding:

The data type or the list of allowable values associated with each Timesheet attribute in a Digital NOTAM encoding are marked in orange in the following diagram: 

Tempdelta - additional versus complete hours

As explained in the general coding rules for schedules - Relation with TimeSlice validity, a TEMPDELTA shall contain a complete description of the operating times. 

Schedules are usually used when encoding availability or activation information, such as in the SAA.ACT, RTE.CLS, AD.CLS, etc. scenarios. In this situation, it is recommended that the input interface provides a "calendar/level" view of the activation/availability, enabling the operator to graphically visualise the status of the feature different times and levels (if applicable), such as in the example below:

In the calendar view, the BASELINE information that remains valid during the Event validity time shall be visibly identified from the information that is specific to the Event, for example by using a different color and fill pattern.

The TEMPDELTA shall contain the complete definition of the activity times, including any eventual time ranges that are recuperated from the BASELINE schedules. Note that according to the OPADD, notification of a schedule modification by NOTAM shall be done by including the new schedule in item E, not in item D. Therefore, the list of Event Scenarios has to include separate scenarios for such situations.

Common coding patterns

The Common coding patterns apply also for Digital NOTAM Event schedules, but with the limitations specified below.

"Daily" and "date" based schedules

Refer to the Common coding patterns "Daily" schedules diagram.The following additional coding rules apply:

• each use of "daily", "on date", "date range", "on weekday", or "from weekday...to weekday" shall be encoded as a single Timesheet, according to the [TSH] and [/TSH] indications in the diagrams;

• "on date" needs to be coded with both startDate and endDate having the same value, unless there is a full day (00:00 to 24:00) in which case the convention for "end of day' needs to be applied and the endDate gets the value of the next date after the startDate.

• if "excluded date" is used, then it shall be encoded as one Timesheet that has excluded='YES',  startDate the value of the excluded date, startTime='00:00', endDate the value of the date that follows the excluded date and endTime='00:00'. Note that this applies also the convention for "end of day" being coded as "00:00 of next day".

"Days of the week" based schedules

Refer to the Common coding patterns "Days of the week" schedules diagram.

Data verification rules

The data verification rules provided in this section shall be followed in order to ensure the harmonisation of the digital encodings provided by different sources. These rules shall be used as complementing the General coding rules for Schedules defined in AIXM Coding Overview - Common Coding Rules - Common coding patterns. In case of contradiction, the rules described below are superseding the general ones.