**2. Life Cycle Cost**

As with every technical system, a military aircraft is designed, and expected to be operated, over a specified life cycle. An operator needs to ensure that the aircraft fleet remains healthy (airworthy) and operationally capable throughout its life. Complex maintenance and sustainment activities are performed to ensure that the aircraft systems operate reliably, structural integrity is assured and upgrades allow it to offer value to the operational capabilities of the defence force. The cost associated with maintenance and sustainment is continuously evolving, and it is generally expected to increase over time. The focus of the discussion is not how this cost evolves but the indirect costs associated with the ownership of military aircraft and particularly military transport aircraft (airlifters).

Military operators may set a lower (start) point and an upper (cut-off) point for the operating cost, both for monitoring/managemen<sup>t</sup> and decision-making purposes. These two points define the acceptable operating margins for an aircraft fleet. The life cycle can be segmented, in broad terms, into four phases: the initial investment, the learning and maturing phase, the maturity phase and the end of life (disposal) of the aircraft (Figure 2).

**Figure 2.** Life cycle, in phases, of military aircraft.

Entry to service requires an initial investment, which accompanies/stems from the procurement contract for new systems. The level of initial investment defines the start point in the cost curve, with costs in this phase associated with:

• Technical training for the engineering and technical staff;


The next phase in the life of aircraft, which may be the most challenging in terms of managing some uncertainty around the performance of a new system, is that of learning and maturing. Inexperienced/smaller operators with fewer resources than larger defence forces may face additional challenges. For example, small operators typically do not have a su fficient level of depth in engineering expertise or in-house technical resources which would help them in resolving early-life challenges. In this phase, the operator needs to:


The maturity phase may need more attention than the learning and maturing phase. As the technical system (aircraft) ages, it can become more resilient or predictable, but the ageing e ffects will start to have an impact on integrity or reliability at the same time. This can be a very interesting period for engineers, since older aircraft o ffer new challenges. Typically, this phase includes:


When the upper (cut-o ff) point is reached (or exceeded in some cases), the decision-makers may place the aircraft at the of end-of-life phase, leading to disposal, storage or decommissioning. Often, these decisions are made on the basis of operational and/or political reasons.
