CNN recently been reported that “the Philippines closed the whole country’s airspace for 6 hours in May to replace malfunctioning electrical equipment.” The shutdown was necessary because there have been a number of breakdowns in the air system which led to thousands of passengers being stranded.
The difference between preventive maintenance and breakdown maintenance is described in Chapter 17 of your Heizer/Render/Munson textbook. Preventive maintenance involves monitoring equipment and facilities along with performing routine inspections and service to keep equipment and facilities reliable. Breakdown maintenance occurs when preventive maintenance fails and equipment/facilities must be repaired on an emergency or priority basis.
Of course, many companies employ both types of maintenance. For example, Suncor refinery in Colorado is currently undergoing planned maintenance of one of its plants. But last December breakdown maintenance was necessitated by a fire on Christmas eve. The Philippines maintenance is more or less a hybrid of the two types of maintenance described in the textbook. It is not breakdown maintenance because there is not a current failure in the system. It is not preventive maintenance in that they are not performing routine inspections and service although it is like preventive maintenance in that it will be scheduled ahead of time rather than occurring during a breakdown.
Planned maintenance provides several advantages. It offers the possibility to account for an expected drop in supply. For example, airlines going to and from the Philippines have the opportunity to adjust their schedules to avoid or minimize the effects of the shutdown. Similarly, Russia provides 4 days of planned maintenance on one of its pipelines. Citizens still have fuel because the stockpiled inventory will be used.
Planned maintenance also provides the opportunity to inform customers or neighbors about possible side effects such as noise or odors from the maintenance, fires flaring from stacks, and, of course, possible service disruptions. The City of Bakkerskloof, South Africa, had time to warn residents about water discoloration after the maintenance of its water unit and to tell residents that trucks would be coming around with water during the maintenance period. Frontier Communications in Beckley WV had time to warn residents that 911 service would be shut down on land lines for 4 hours during preventive maintenance and that customers should use their cellphones during that period for 911 calls.