*3.1. Diverse and Non-Typical Operations*

The nature of the military aircraft operations is dictating or imposing diverse and often non-typical (when comparing to civil transport aircraft) mission profiles and operating environment. This, in turn, has an e ffect on the cost of sustainment, since the maintenance programme needs to capture proactively any problems that may reduce the reliability of the aircraft systems.

### *3.2. Reliance on O*ff*shore Maintenance Services*

Heavy (depot-level) maintenance and, in some cases, intermediate-level maintenance, may have to be performed at overseas maintenance centres. This is the case when such capability has not been developed in-house (within the defence force organisation or at in-country aircraft maintenance organisations). Military operators have to rely on this set of services, which, in the long term, can have a substantial impact on sustainment cost. This includes out of country capabilities, o ffered by commercial entities. An example of specialised maintenance providers for airlifters is the Marshall Aerospace and Defence Group in the United Kingdom, which has extensive maintenance capabilities on the Lockheed Martin C-130 aircraft platform [2].

### *3.3. Disconnect between Military and Civil Airworthiness Requirements*

Civil and military aviation are, by default, not aligned or consistent with each other, in terms of both regulations and practice. There are good reasons for this di fferent treatment, primarily attributed to the nature of the operation of the military transport aircraft. This disconnect creates complexities and imposes defence-specific requirements for the preservation of the continuing airworthiness of the aircraft, even when the same aircraft type has dual (civil–military) certification. For example, military transport aircraft may have to be retrofitted with defence-specific equipment, such as cha ff and flare dispensers (for self-protection purposes). This equipment cannot be certified under a civil regulatory framework and this activity adds cost for the military aircraft owner/operator.

### *3.4. Lack of Civil Type Certificate*

Type certification of some airlifters does adhere to civil (i.e., the European Aviation Safety Agency, EASA, or the Federal Aviation Authority, FAA) regulations. The Airbus A400 M is a relatively recent example of a civil (EASA) certified airlifter [3]. However, for most types, this is not the case. This may have a smaller impact on cost, though modern safety regulations (and certification standards) for civil aircraft have progressively evolved to become more user-friendly, meaning higher e fficiencies and improved reliability, resulting in lower long-term sustainment costs.
