Unification of Military and Civil Aircraft Certification Procedure

Unification of Military and Civil Aircraft Certification Procedures

Airworthiness and Type Certification 

‘Airworthiness’ is defined as the demonstrated capability of an aircraft to satisfactorily fulfill the mission requirements with acceptable level of safety and reliability. Airworthiness does not guarantee an ‘absolute safety’ rather an ‘acceptable level’ of safety which is decided as mutually agreed among designer, manufacturer and the user on one side and the state or regulator on the other side. The foundation for this is the acceptability from safety consideration on one hand and the practicability form the point of technical feasibility and cost of compliance towards design and manufacture. The ‘Type Certification’ on the other hand is a legal declaration by a competent authority that the product has been designed, developed, evaluated and productionised in such a manner that its quality, reliability and integrity meets or exceeds the specified requirements.

Flight Safety and Risk Threshold

         ‘Safety’ of any flight would depend primarily upon, whether we are operating below or above the ‘Risk Threshold’. The basic tenet of flight safety is to ensure that the chances of achieving the tasks should be optimal while risks are minimal. The ‘flight safety directorate’ is to ensure that in peace time high level of risks is avoided. This is because the accidents have very deleterious effects on the morale of the flier. During the war time, however, task achievement is paramount and high degree of risk may have to be taken. Safety levels are quantified as ‘Casualties per Ton Kilometer of transportation (CTK)’ for civil aircraft while for military aircraft; it is ‘Accidents Rate’ per 10,000 hours of flight.

Military and Civil Aircraft Design Procedures

           While, commercial aircraft has a single mission of safe and comfortable ferrying of passenger and cargo, the military aircraft have to perform far more varied and different missions with each requiring different design requirements to be satisfied. Further, commercial aircraft uses only proven technologies, military aircraft design, to get an edge over the contemporaries, exploits latest but not fully qualified ‘developments in technologies’.  The new technologies also get certified along with the military aircraft certification. An aircraft design is a ‘trade off’ amongst diversified requirements. The ‘trade off criteria’ is different for commercial and military aircraft. For example: while performance and stealth are high priority for combat fleet, flying qualities and safety is most desirable for commercial aircraft.

     

         To maintain international safety of air transportation, ICAO has imposed that every member country should have a Civil Aviation Authority (CAA) empowered by the statutory rules of the country to impose regulations to maintain air safety. Certification is to be accorded by these CAAs only (for example: FAA (in USA) and EASA (European countries)) on compliance to the regulations. The military aircraft being ‘state owned’ undergoes government ‘self certification’ as per Mil–Std 516B (USA), JAP-100 (UK), DDPMAS -2002 (India).

System Safety: Military and Civil Aircraft

       System safety of military aircraft design is as per Mil-Std-882 while for civil aircraft FAR 25.1309 and SAE-ARP 4761 are followed. Mil 882 uses improbable (<10^-7) and ARP 4761 considers extremely remote (< 10^-9) as the limiting values. This is because military aircraft design accepts a higher risk for mission accomplishment. However both the designs follow the basic tenet of airworthiness, i.e. there should exist an inverse relation between the probability of occurrence of an event and the degree of hazard inherent in its effect. 

Inter-Operability of Civil and Military aircraft in the International/National Air Space

         The commercial aircraft need to comply with ICAO requirements of communication, navigation and surveillance (CNS) and Air Traffic Management (ATM). The latest ICAO decision mandated use of GNSS (Global Navigation Satellite System) and ADS-B (Automatic Dependence Surveillance Broadcast). With airspace becoming congested, dedicated airspace for military operation has become an issue. Therefore, optimum utilization of airspace has become essential. Further, when military aircraft flies in the national air space, it would share the airspace with national and international traffic, therefore, the military aircraft also is required to comply with the same requirement of CNS, ATM and TCAS. Thus for the interoperability of the two aircraft a common frame of rules are to be formulated.   The concept ‘Performance Based certification’ (PBC) has been proposed by Euro Control for the military systems to meet civil CNS/ATM requirement so as to fly in common air space.

Civil Certification of Military Aircraft

        Airbus military A400M Transport aircraft has been type certified by EASA following CS-25 and Initial Operational Clearance accorded on compliance to the additional military requirement indicated by the French Air Force. Lockheed martin has notified FAA for type certification of L-382J Hercules (civil variant of C-130J Super Hercules) to be marketed as LM-100J. In India Advanced Light Helicopter, Dhruv designed to meet UK MOD Def-Stan-00-970 was type certified by military airworthiness authority CEMILAC, DRDO. The same helicopter was later accorded type certification for civil use by DGCA, Min of Civil Aviation, Gov. of India, based on the tests earlier conducted. US military operates FAA certified aircraft as military commercial derivative aircraft (MCDA). FAA has released an Advisory Circular AC–20-169 and created a Military Certification Office to provide certification and continued airworthiness of MCDA. Sweden has also harmonized civil and military certification procedure considering cost of testing and certification of the same product more than once to satisfy two different authorities and applications.

        

Unified Procedure – Recommendation

         For criticality of application of military combat aircraft, it is recommended to continue the military certification of combat aircraft. However, considering the enormous cost and effort required for certification, it is advisable to have unified certification for the transport category aircraft for use in civil and military application. A unified approach is recommended for the certification of non combat aircraft as follows:

a)      Design and Production Organisation approval (DOA and POA) to be accorded following             international norms as per ICAO Airworthiness Manual. The design codes to be followed are as         per appropriate FAR category.

b)      The basic aircraft (green aircraft) can be certified on compliance to FAR requirements. The                 additional military staff requirements are to be marked as ‘Critical Review Item’ (CRI).

c)      While worldwide, the civil certification authorities have wider expertise in aircraft certification           and therefore, are entrusted for military aircraft certification also. In India, DGCA are not                   considered to possess requisite manpower and expertise to take up aircraft certification.                       Considering the availability of manpower and other infrastructure, CEMILAC, DRDO is                     recommended to take up the certification activity. 

d)      However, ICAO recognises only DGCA and not CEMILAC. Thus the type certification for civil         application has to be endorsed by DGCA. Thus it is required to have a close co-ordination                   between CEMILAC and DGAQA at all stages of aircraft certification. 

e)      It is recommended to from an apex organisation (Aerospace Commission) for overseeing these       two organisations and provides directions so that duplication of certification effort is avoided.  

f)       The apex organisation will give direction towards acceptance of all CRIs based on the military           compliance and accord operational clearance for service induction of the aircraft.

g )    To provide interoperability in the national airspace, performance based certification and                      unification of CNS/ATM to be implemented. 

Conclusion
        Certification is a costly and time consuming activity. Besides it is a specialised and a different task compared to design and manufacturing. Safety is a concern for both civil and military authorities. It therefore does not make sense to spend time and effort to certify the same aircraft twice just to satisfy two different regulatory autheirites.