Page 99 - Global Project Management Handbook

TOTAL LIFE-CYCLE SYSTEM MANAGEMENT 4-7

MCT = total time − NMCT
Therefore,
total time − NMCT
A =
O
total time
where MCT = mission-capable time
NMCT = non-mission-capable time

FIGURE 4.6 Operational Availability.

NMCT = TCM + TPM + ALDT
NMCT consists of
TCM = total corrective maintenance downtime when the system is
undergoing repair because it failed
TPM = total preventive maintenance downtime when the system is
undergoing scheduled maintenance which renders it NMC
ALDT = administrative or logistics delay time when the system is NMC
because it is awaiting logistics support resources (spares,
personnel, etc.)
FIGURE 4.7 Non-mission-capable time.

number of systems × number of annual missions × mission time
TCM = × M CMT
MTBF

Number of systems = the total number of systems the user can task perform a mission
Number of annual missions = the total number of times that a mission is performed
Mission time = the average time required to perform the mission once

Example: Number of systems (aircraft) = 20 (total number in the operational inventory)
Number of annual missions = 180 (total sorties per year per system)
Mission time = 8 hours
MTBF = 200 hours
M CMT = 4 hours

20 × 180 × 8
TCM = × 4 = 576 hours
200

FIGURE 4.8 Calculating TCM.