Expert system scheduler and scheduling method

What is claimed is:

1. An expert system scheduler for flexibly scheduling training events at a plurality of training sites notwithstanding the occurrence of resource conflicts, each training site comprises one of a plurality of distributed computers that are interconnected by means of an interconnecting link, the plurality of distributed computers interconnected to a central processor including a database, and wherein the remainder of the computers comprise remote processors, and wherein the database comprises: (1) a list of students input from the plurality of remote computers, (2) a list of instructors, and (3) a list of available flight training events, and wherein the availability of the students, the instructors and the available training events vary over time, and wherein the expert system scheduler comprises processing means that are disposed on each of the remote processors, said expert system scheduler comprising:

means for selectively generating a master plan in response to training requests supplied by users, which master plan provides an event flow that specifies target dates for each training event, but does not specify the exact time or resources and does not take into account whether sufficient resources are available on a target date, which training requests inform the scheduler that a specific number of users should be scheduled for a particular training event, and stipulate required starting and ending dates for the events, the master plan providing users with a preview of the proposed event sequence and an overview of all events which are targeted for the same date;

means for adjusting the master plan so that users may adjust starting, interim and ending training dates in order to express preferred scheduling constraints;

means for selectively generating a master schedule in response to training requests and the users preferred scheduling constraints which reserves specific dates, times, locations and resources for each training event to fulfill scheduled training requests;

means for generating conflict alerts to notify users if conflicts with the master schedule exist;

means for generating revised training requests in response to conflict alerts; and

means for automatically generating schedule revision options in response to the revised training requests which appropriately reschedule the sites in view of conflicts;

wherein the expert system scheduler flexibly schedules and reschedules training events at each of the sites notwithstanding resource conflicts, and wherein schedules are automatically generated and conflicts resolved.

2. The expert system scheduler of claim 1 which further comprises:

means for selectively generating schedules indexed on user, instructor, resource, and event in response to user requests.

3. The expert system scheduler of claim 1 which further comprises:

means for displaying the master plan to provide facilities for users to review and revise the master plan.

4. The expert system scheduler of claim 1 which further comprises:

means for initializing a workshift calendar and a scheduling parameters database that stipulate general scheduling constraints, which parameters are used by the scheduler to restrict the dates and times during which resources may be used and to establish priorities by which resources are allocated.

5. An expert system scheduler for flexibly scheduling training events at a plurality of training sites notwithstanding the occurrence of resource conflicts, each training site comprises one of a plurality of distributed computers that are interconnected by means of an interconnecting link, the plurality of distributed computers interconnected to a central processor including a database, and wherein the remainder of the computers comprise remote processors, and wherein the database comprises: (1) a list of students input from the plurality of remote computers, (2) a list of instructors, and (3) a list of available flight training events, and wherein the availability of the students, the instructors and the available training events vary over time, and wherein the expert system scheduler comprises processing means that are disposed on each of the remote processors, said expert system scheduler comprising:

means for selectively generating a master plan in response to training requests supplied by users, which master plan provides an event flow that specifies target dates for each training event, but does not specify the exact time or resources and does not take into account whether sufficient resources are available on a target date, which training requests inform the scheduler that a specific number of users should be scheduled for a particular training event, and stipulate required starting and ending dates for the events, the master plan providing users with a preview of the proposed event sequence and an overview of all events which are targeted for the same date;

means for users to adjust the starting, interim and ending training dates in order to select preferred scheduling times;

means for selectively generating a master schedule in response to training requests which reserves specific dates, times, locations and resources for each training event to fulfill scheduled training requests;

means for selectively generating schedules indexed on user, instructor, resource, and event in response to user requests;

means for generating conflict alerts to notify users if conflicts with the master schedule exist;

means for generating revised training requests in response to conflict alerts; and

means for automatically generating schedule revision options in response to the revised training requests which appropriately reschedule the sites in view of conflicts;

wherein the expert system scheduler flexibly schedules and reschedules training events at each of the sites notwithstanding resource conflicts, and wherein schedules are automatically generated and conflicts resolved.

6. The expert system scheduler of claim 5 which further comprises:

means for displaying the master plan to provide facilities for users to review and revise the master plan.

7. The expert system scheduler of claim 5 which further comprises:

means for initializing a workshift calendar and a scheduling parameters database that stipulate general scheduling constraints, which parameters are used by the scheduler to restrict the dates and times during which resources may be used and to establish priorities by which resources are allocated.

8. A method of flexibly scheduling training events at a plurality of training sites notwithstanding the occurrence of resource conflicts, each training site comprises one of a plurality of distributed computers that are interconnected by means of an interconnecting link, the plurality of distributed computers interconnected to a central processor including a database, and wherein the remainder of the computers comprise remote processors, and wherein the database comprises: (1) a list of students input from the plurality of remote computers, (2) a list of instructors, and (3) a list of available flight training events, and wherein the availability of the students, the instructors and the available training events vary over time, and wherein the expert system scheduler comprises processing means that are disposed on each of the remote processors, said method comprising the steps of:

selectively generating a master plan in response to training requests supplied by users, which master plan provides an event flow that specifies target dates for each training event, but does not specify the exact time or resources and does not take into account whether sufficient resources are available on a target date, which training requests inform the scheduler that a specific number of users should be scheduled for a particular training event, and stipulate required starting and ending dates for the events, the master plan providing users with a preview of the proposed event sequence and an overview of all events which are targeted for the same date;

adjusting the master plan so that users may adjust starting, interim and ending training dates in order to express preferred scheduling constraints;

selectively generating a master schedule in response to training requests and the users preferred scheduling constraints which reserves specific dates, times, locations and resources for each training event to fulfill scheduled training requests;

generating conflict alerts to notify users if conflicts with the master schedule exist;

generating revised training requests in response to conflict alerts; and

automatically generating schedule revision options in response to the revised training requests which appropriately reschedule the sites in view of conflicts;

wherein the method flexibly schedules and reschedules training events at each of the sites notwithstanding resource conflicts, and wherein schedules are automatically generated and conflicts resolved.

9. The method of claim 8 which further comprises the step of:

displaying the master plan to provide facilities for users to review and revise the master plan.

10. The method of claim 8 which further comprises the step of:

selectively generating schedules indexed on user, instructor, resource, and event in response to user requests.

11. The method of claim 8 which further comprises the step of:

initializing a workshift calendar and a scheduling parameters database that stipulate general scheduling constraints, which parameters are used by the scheduler to restrict the dates and times during which resources may be used and to establish priorities by which resources are allocated.

12. A method of flexibly scheduling training events at a plurality of training sites notwithstanding the occurrence of resource conflicts, each training site comprises one of a plurality of distributed computers that are interconnected by means of an interconnecting link, the plurality of distributed computers interconnected to a central processor including a database, and wherein the remainder of the computers comprise remote processors, and wherein the database comprises: (1) a list of students input from the plurality of remote computers, (2) a list of instructors, and (3) a list of available flight training events, and wherein the availability of the students, the instructors and the available training events vary over time, and wherein the expert system scheduler comprises processing means that are disposed on each of the remote processors, said expert system scheduler comprising:

selectively generating a master plan in response to training requests supplied by users, which master plan provides an event flow that specifies target dates for each training event, but does not specify the exact time or resources and does not take into account whether sufficient resources are available on a target date, which training requests inform the scheduler that a specific number of users should be scheduled for a particular training event, and stipulate required starting and ending dates for the events, the master plan providing users with a preview of the proposed event sequence and an overview of all events which are targeted for the same date;

displaying the master plan to provide facilities for users to review and revise the master plan;

adjusting the starting, interim and ending training dates in order to select preferred scheduling times;

selectively generating a master schedule in response to training requests which reserves specific dates, times, locations and resources for each training event to fulfill scheduled training requests;

selectively generating schedules indexed on user, instructor, resource, and event in response to user requests;

generating conflict alerts to notify users if conflicts with the master schedule exist;

generating revised training requests in response to conflict alerts; and

automatically generating schedule revision options in response to the revised training requests which appropriately reschedule the sites in view of conflicts;

wherein the expert system scheduler flexibly schedules and reschedules training events at each of the sites notwithstanding resource conflicts, and wherein schedules are automatically generated and conflicts resolved.

13. The method of claim 12 which further comprises the step of:

selectively generating schedules indexed on user, instructor, resource, and event in response to user requests.

14. The method of claim 12 which further comprises the steps of:

initializing a workshift calendar and a scheduling parameters database that stipulate general scheduling constraints, which parameters are used by the scheduler to restrict the dates and times during which resources may be used and to establish priorities by which resources are allocated.

Description Submit all comments and votes

BACKGROUND

The present invention relates generally to scheduling of training resources, and more particularly, to an expert system scheduler that performs administrative and managerial functions necessary for operating, managing and revising of the schedules for training systems.

Currently, the scheduling of Air Force flight training classes (events) at a plurality of training sites is accomplished using a plurality of interconnected, distributed computers that are interconnected to a central database. The database generally comprises, among other things, a list of students input from the plurality of distributed computers, a list of instructors, and a list of available flight training events. However, schedules are apt to vary over time, since necessary resources are not always available at the time they are required, and since conflicts are apt to arise from time to time.

Consequently, it would be an improvement in the art to provide for a scheduler and scheduling method that is flexible in that it is capable of dynamically rescheduling users and resources in order to adjust for conflicts that arise.

SUMMARY OF THE INVENTION

In order to overcome the limitations of conventional scheduling systems and methods, the present invention is an expert system scheduler for flexibly scheduling training events at a plurality of training sites notwithstanding the occurrence of resource conflicts. Each training site comprises one of a plurality of distributed computers that are interconnected by means of an interconnecting link. The distributed computers are interconnected to a central processor that includes a database. The database at least comprises a list of students input from the plurality of remote computers, a list of instructors, and a list of available flight training events. The availability of the students, the instructors and the available training events vary over time.

The expert system scheduler generally comprises a computer processor that is disposed at each of the remote sites. Each expert system scheduler comprises means for selectively generating a master plan in response to training requests supplied by users. The master plan provides an event flow that specifies target dates for each training event, but does not specify the exact time or resources and does not take into account whether sufficient resources are available on a target date. The training requests inform the scheduler that a specific number of users should be scheduled for a particular training event, and stipulate required starting and ending dates for the events. The master plan provides users with a preview of the proposed event sequence and an overview of all events which are targeted for the same date.

The scheduler also comprises means for adjusting the master plan so that users may adjust starting, interim and ending training dates in order to express preferred scheduling constraints. The scheduler also comprises means for selectively generating a master schedule in response to training requests and the users preferred scheduling constraints which reserves specific dates, times, locations and resources for each training event to fulfill scheduled training requests. Furthermore, the scheduler comprises means for generating conflict alerts to notify users if conflicts with the master schedule exist. Means are provided for generating revised training requests in response to conflict alerts. Means are provided for automatically generating schedule revision options in response to the revised training requests which appropriately reschedule the sites in view of conflicts.

In operation, the expert system scheduler flexibly schedules and reschedules training events at each of the sites notwithstanding resource conflicts, and wherein schedules are automatically generated and conflicts resolved.

The expert system scheduler and scheduling method in accordance with the present invention provides administrative and managerial resources necessary for the day-to-day operating, managing, and revising of training, user, instructor and resource schedules. The expert system scheduler comprises an integrated system of hardware and software that provides schedule generation required for management of the training system. The expert scheduler includes capabilities not currently available in existing scheduling systems. These capabilities include: expert system scheduling capability comprising an unlimited number of students, resources and instructors; schedules generated for a full year to the 15 minute interval level with all priorities satisfied and conflicts resolved or identified; seamless interfacing of commercial software packages and custom software into the system; and software that is readily adaptable to a variety of hardware platforms.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of the present invention may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:

FIG. 1A is a block diagram illustrating the basic organizational concept of a system that uses an expert scheduler in accordance with the present invention;

FIG. 1B is a block diagram illustrating process flow details of the expert scheduler in accordance with the present invention that is employed in the system of FIG. 1A;

FIG. 2 is a functional diagram showing the operation of the expert scheduler of the present invention as applied to an exemplary embodiment in an aircrew training system;

FIG. 3 is a diagram giving the transactional perspective of the training system incorporating the invention as diagrammed in FIG. 2;

FIG. 4 is a diagram giving the service perspective of the training system incorporating the expert scheduler as diagrammed in FIGS. 2 and 3;

FIG. 5 is a diagram giving the data flow perspective of the training system incorporating the invention as diagrammed in FIGS. 2-4;

FIGS. 6A and 6B are a diagram giving the object perspective of the training system incorporating the invention as diagrammed in FIGS. 2-5;

FIGS. 7A and 7B are a diagram giving the student state perspective of the training system incorporating the invention of FIGS. 2-6;

FIGS. 8A and 8B are a diagram giving the resource state perspective of the training system incorporating the invention of FIGS. 2-7; and

FIGS. 4A and 4B are a diagram giving the training event state perspective of the training system incorporating the invention of FIGS. 2-8.

DETAILED DESCRIPTION

The present invention is a scheduling system for use with training systems. It should be clearly understood that the expert scheduler of the present invention finds utility in any kind of training system that provides training for any purpose. In the description that follows hereinafter, the invention will be described in relation to the training of aircrews for the operation of aircraft. For purposes of explanation, an exemplary embodiment of the invention in a military environment is shown, but it should be clearly understood that the invention also has utility in a civilian setting.

Referring now to FIG. 1A, the exemplary embodiment of the scheduler of the present invention is incorporated into an aircrew training system 10 for a military aircraft identified as the C-141. The aircrew training system 10 involves the use of academic media such as classrooms, training devices such as ground-based flight simulation trainers, and training flights in the air. In addition, it involves a computer network having terminals located at a central site 11, and at a plurality of training sites 12. In addition, other locations (not shown) may be tied into the aircrew training system 10, such as reserve bases, Air National Guard bases, and the like. The computer data base for the aircrew training system 10 is located at the central site 11, and the training facilities are located at the training sites 12. Computer terminals at the central site 11 and at the training sites 12 are connected together in a computer network by means of telephone lines. In addition, remote computer terminals may also be tied into the network from various additional locations such as reserve bases and Air National Guard bases. Typically, the computer network is interconnected by both dedicated and dial-up telephone lines, and typically the network may employ Intel 80386 machines running UNIX V, release 3.2. The scheduler of the present invention comprises an integrated system of hardware and software which provides scheduling of students, resources and instructors. The students may be studying for the position of pilot, co-pilot, flight engineer, air refueling engineer, weapons engineer, and etc. The resources may include flight bases, formal school, seminars, and simulator trainers including cockpit procedures trainers, weapon system trainers, air refueling part task trainers, load master part task trainers, and the like.

The purpose of the scheduling system of the present invention is to perform all administrative and managerial functions necessary for operating, managing and revising of the schedules for the aircrew training system 10. It is to be understood that the expert scheduler of the present invention is to be integrated into the already existing aircrew training system 10. The expert scheduler of the present invention is embedded as a software subsystem in the aircrew training system 10, and is delivered on a 80386 based computer element at each training site 12. The expert scheduler of the present invention is implemented as a demand driven, priority constraint based scheduling system. In response to user's training requests, the expert scheduler delivers earliest opportunity schedules which satisfy allocation policies under limited resource availability.

The primary purpose of the expert scheduler of the present invention is to facilitate orderly scheduling of training events. Key features of the expert scheduler include automatic schedule generation, objective, consistent and valid schedules, the issuance of schedule conflict alerts, flexible scheduling control policies, and effective scheduling refinement options.

Referring now to FIG. 1B, the expert scheduler of the present invention located at one of the remote sites 12 operates generally as follows. The remote site 12 is linked to the central data base 11. During system installation, users input initial constraints into a computer 20. These relate to a workshift calendar and a scheduling parameters database which stipulate general scheduling constraints 21. These parameters are used by the scheduler of the present invention to restrict the dates and times during which resources may be used and to establish priorities by which resources are allocated. Users input training requests 22 to inform the scheduler that a particular course or training event must be held for a specified number of students. These requests also stipulate required starting and ending dates for the courses. On request, the scheduler produces a master plan 23. The master plan 23 lays out course flows which accommodate the training requests 22 at a gross level. It specifies the target date for holding each course training event, but does not specify the exact time or resources. Nor does it take into account whether or not sufficient resources are available during the target date. This master plan 23 provides users with a preview of the proposed event sequence and an overview of all events which are targeted for the same date. Users review and revise the master plan 23. If appropriate, users manually adjust the starting, interim or ending training dates 24 to express preferred scheduling constraints. Upon user request, the scheduler generates a master schedule 25 which reserves specific dates, times, locations and resources for each event as necessary to fulfill the training requests. The workshift calendar, scheduling parameters, training requests 22 and master plan 23 are used to constrain and guide the scheduling process. Upon user request, the scheduler publishes a master calendar 26 and schedules per course, crew, student, instructor, resource and event. The scheduler also generates conflict alerts 27 to notify users if constraints are violated, e.g. scheduled date is beyond planned target date. When exception conditions occur, e.g. a class is cancelled due to device failure, users will submit a revision request 28. In response, the scheduler offers automatic or manual schedule revision options 30 including utilities to identify alternative resources and subsequent opportunities.

The expert scheduler of the present invention prints out a large number of documents, including reports, schedules, calendars and plans. An inventory of the documents produced by the scheduler is given in Table I.

TABLE I ______________________________________ Document Inventory. Report Description ______________________________________ Alert Report Detected constraint violations Course Schedule Detailed event schedule per course Crew Schedule Detailed event schedule per crew Date Calendar Standard monthly calendar Event Schedule Detailed event schedule per event Flight Report Scheduled flight events, flight requests Instructor Schedule Detailed event schedule per instructor Location Schedule Detailed event schedule per location Master Plan Course flow, target event dates Master Schedule Detailed event schedule per day Next Opportunity Report Alternative date, time & resource for event Projections Report Potential schedule for modified workshift Resource Option Report Alternative resource for event on date Resource Report Site inventory & resource qualifications Resource Schedule Detailed event schedule per resource Resource Utilization Report Projected resource supply vs demand Scheduling Parameters Scheduling constraints & preferences Student Enrollment Class Roster Student Schedule Detailed event schedule per student Throughput Report Projected number of graduates per type Workshift Calendar Operating Hours per resource ______________________________________

In addition to the documents shown in Table I, the expert scheduler also displays a number of screens that are used in managing and administering the training system. The administrative screens available are shown in Table II.

TABLE II ______________________________________ Administration Screen Inventory. Screen Description ______________________________________ Resource Item Admin. Define resource inventory & workshifts Course Administration Define course syllabi Preference Admin. Define resource allocation preferences Training Administration Request training & schedule revisions Appointment Admin. Override automatic schedule Student Administration Enroll students in training courses ______________________________________

Selectors provide the user options during administration and reporting. The selectors available are listed in Table III, along with a brief description.

TABLE III ______________________________________ Selector Inventory. Screen Description ______________________________________ sel.sub.-- ctype Selects one course type sel.sub.-- ctdr Selects one course type, date range sel.sub.-- cid Selects one course type, course id sel.sub.-- event Selects one course type, event sel.sub.-- event.sub.-- drg Selects one course type, date range sel.sub.-- cid.sub.-- ev Selects one course type, course id, event sel.sub.-- crew Selects one course type, course id, crew sel.sub.-- ev.sub.-- crew Selects one course type, course id, event, crew sel.sub.-- cidst Selects one course type, course id, student id sel.sub.-- ctdrg Selects one course type, date range sel.sub.-- rtype Selects one resource type sel.sub.-- rid Selects one resource type, resource id sel.sub.-- rypedrng Selects one resource type, date range sel.sub.-- res.sub.-- drng Selects one resource type, resource id, date range sel.sub.-- stid Selects one student id sel.sub.-- date Selects one date sel.sub.-- drg Selects one date range (i.e. begin date, end date) sel.sub.-- indr Selects one instructor, date range sel.sub.-- loc.sub.-- drg Selects one location, date range sel.sub.-- month.sub.-- rng Selects start month, year & end month year ______________________________________

The system may display various messages or prompts. These user interface messages are listed in Table IV, along with their meanings.

TABLE IV ______________________________________ Message Dictionary. Message Text ______________________________________ err.sub.-- backup err.sub.-- cid Invalid course id err.sub.-- config err.sub.-- crew Invalid crew err.sub.-- ctype Invalid course type err.sub.-- date Invalid date err.sub.-- dbeg Invalid start date err.sub.-- delay err.sub.-- dend Invalid end date err.sub.-- dur Invalid time duration err.sub.-- event Invalid event err.sub.-- fclose System error during file close err.sub.-- fcreate System error during file create err.sub.-- ferase System error during file erase err.sub.-- fname System error during file naming err.sub.-- fopen System error during file opening err.sub.-- fread System error during file reading err.sub.-- fseek System error during file searching err.sub.-- fwrite System error during file writing err.sub.-- inprqd Input required to continue err.sub.-- inst Invalid instructor id err.sub.-- loc Invalid location err.sub.-- lp Printer not available err.sub.-- nochoice Choice list not available err.sub.-- nodisksp No disk space available err.sub.-- prereq err.sub.-- restore err.sub.-- rid Invalid resource id err.sub.-- rtype Invalid resource type err.sub.-- stid Invalid student id err.sub.-- tbeg Begin time must be less than end time err.sub.-- time Invalid time pmt.sub.-- cid Please input a course id pmt.sub.-- crew Please input a crew pmt.sub.-- ctype Please input a course type pmt.sub.-- date Please input a date pmt.sub.-- dbeg Please input a start date pmt.sub.-- dend Please input an end date pmt.sub.-- dur Please input a duration for the event pmt.sub.-- event Please input an event pmt.sub.-- inst Please input an instructor id pmt.sub.-- loc Please input a location pmt.sub.-- rid Please input a resource id pmt.sub.-- rtype Please input a resource type pmt.sub.-- stid Please input a student id rpt.sub.-- full Report requests are full - please try later rpt.sub.-- nodata No data to report sos.sub.-- cid A course id identifies a particular course; e.g. 91001 sos.sub.-- crew sos.sub.-- ctype A course type sos.sub.-- date Dates are entered in form: MM-DD-YY; e.g. 12-31-90 sos.sub.-- dbeg Start date is the date of the first training event sos.sub.-- dend End date must be no later than start date sos.sub.-- event An event identifies a training activity; e.g. hydraulics sos.sub.-- inprqd sos.sub.-- inst sos.sub.-- loc sos.sub.-- lp sos.sub.-- nochoice Sorry - no choices available at this point sos.sub.-- nomsg Sorry - no help available at this point sos.sub.-- rid sos.sub.-- rtype sos.sub.-- stid ver.sub.-- del.sub.-- apt ver.sub.-- del.sub.-- cid ver.sub.-- del.sub.-- ctype ver.sub.-- del.sub.-- enrl ver.sub.-- del.sub.-- rid ver.sub.-- del.sub.-- rsv ver.sub.-- del.sub.-- rtype ver.sub.-- del.sub.-- trq ______________________________________

As indicated hereinabove, the scheduler of the present invention provides orderly generation of schedules for the training system. This function incorporates rule based Prolog expert system scheduling algorithms for the production of automated schedules to match student training requirements with available instructors, training resources, and training flights for the production of site-specific schedules for the C-141 aircrew training system (ATS). This function:

(a) provides for long range (one year) predictions of resource requirements as compared to resource availability;

(b) provides for resolution of scheduling conflicts;

(c) schedules training events specified in the course syllabi and/or by instructor/training management system (TMS) recommendations against the site master calendar and available training media and instructors;

(d) schedules training devices for Air Force-requested and conducted training events;

(e) requests flight training to include mission requirements which fulfill student training needs;

(f) considers student availability for training and priority for training in matching students and training events;

(g) provides for on line scheduling in each flying squadron with the capability to update the local training flight and schedule files at least daily for ATS formal school training and continuation training (both flying and ground training events);

(h) provides the capability to generate and update on a daily basis each student's ground and flight training requirements;

(i) stores generated schedules for on line retrieval, modification, and printing;

(j) alerts the scheduler when a training medium or device is in danger of exceeding its normally scheduled capacity, and when it is in danger of exceeding programmed surge capacity; and

(k) provides for assignment of start-of-day time for instructor and student on a daily basis, or allow use of a default time (allows scheduling to the hour versus to the day).

The expert scheduler of the present invention provides prioritization. Prioritization occurs on the following basis. Item (1) has priority over item (2), item (a) over item (b), and so on.

ACADEMIC MEDIA (COMPUTER BASED TRAINING, COCKPIT PROCEDURES TRAINER, PART TASK TRAINER, EXCEPT AIR REFUELING PART TASK TRAINER)

(1) Students enrolled in formal school course.

(a) Within one week of graduation.

(b) Those delayed by 1 day or more.

(2) Students attending in-unit training courses.

(a) Those delayed by 1 day or more.