Why is designing for sustainment a critical function in military equipment?

Designing for sustainment is a critical function in military equipment largely because of the long life cycle of such assets. As military equipment is often in service for many decades, the average service life can extend significantly, with projections indicating that it may reach up to 54 years. This longevity means that the equipment must be designed not only for immediate operational effectiveness but also for ease of maintenance, upgrades, and modifications over time.

A focus on sustainment ensures that the equipment remains functional and relevant throughout its entire lifecycle, accommodating different technological advancements and changing mission requirements. Factors such as maintainability, supportability, and logistics are essential to making sure that equipment can be sustained effectively, ultimately leading to better operational readiness and reduced downtime. Thus, option D reflects the necessity to design with this extended lifespan in mind, ensuring that the military can efficiently manage and support its assets over a substantial period.