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Inevitably there will arise events that will impact a company's shop floor so profoundly that they must be considered catastrophes.  They represent the ultimate schedule decay.

A catastrophe, by definition, renders useless the schedules presented on one or more Machine Load Lists from the onset of the catastrophe.  Because of the precedence constraints on operations defined by the shop work orders' routings, it is generally safe to assume that the unuseability of one machine's schedules probably means that all machine's schedules are unusable.

Catastrophes generally fall into two broad groups:  Those that impact

1. the shop's resources, or
2. the material or parts on the shop work orders themselves.

Recovery scheduling usually follows a declaration to PROSPAC as to the nature of the catastrophe.  However a recovery production plan may be needed beyond the simple declaration of the catastrophe.  In that event, those in production control may use PROSPAC's "What if ...?" mode to propose and develop the recovery production plan.

In any case the final result is the re-publication of the three primary schedule documents:

Catastrophic events that impact machine resources are expressed through a feature called pre-scheduled activity.  PROSPAC comes loaded with 30 default pre-scheduled activity types, ranging from Machine Breakdown to Tool Tryouts. 

Pre-scheduled activities are declared by identifying their type, naming the machine to which they apply, and setting the beginning and ending date and time pair.

Catastrophic events that impact the substance of one or more shop work orders are generally expressed through what are called a shop work order's variables:

Unforeseen but urgently needed shop work orders and those with irreparable material damage are two rather common catastrophes that befall many jobshops and make-to-order manufacturers.

EXAMPLE ...

There is an urgent priority in the commercial aircraft manufacturing business called AOG (Airplane On Ground), the highest priority that can be assigned to a shop work order.  Production control creates AOG shop work orders immediately upon notification, releases them to the shop floor with the highest external priority, a 3, and assigns them release and due dates that are in the past (which indirectly causes PROSPAC's internal priority mechanism to assign their operations the highest dynamic priorities in its schedule "engine").

Because jobshops and make-to-order shops tend to purchase only the material required to make the customer's order, there is usually little or no provision made for significant material losses, especially when the raw materials are designated "precious" or otherwise entail high cost.

Therefore such raw material or purchased part that is either lost or damaged to the extent that it must be scrapped, engenders a catastrophic event.

Any shop work orders with such material loss or damage have their material hold status set to ON, which removes unposted operations from the Machine Load Lists.  Once a disposition is determined, the work order's release date is readjusted to that future date when replacement material is expected, the material hold status is set to OFF, and the external priority is set to 3.

EXAMPLES ....

Not all recovery scheduling impacts the shop on an immediate basis:  The projected loss of a machine, due to unscheduled maintenance, may be delayed a few days while replacement parts are procured. 

A customer engineering change that requires a new manufacturing process, will only be effective for shop work orders released after a date 4 months from now.

But when the impact is immediate, production control's first order of business is to supply the shop floor with Machine Load Lists that direct their activities with the catastrophe incorporated into the recovery schedule.  This provides the greatest possible continuity of shop floor operations.

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Last modified:  October 13, 2001