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On-board equipment is the collection of appliances, systems and devices which enables:

aircraft control, including aircraft attitude and its movement pattern control during transportation and combat missions;

• aircraft power supply;

• crew and passengers life support.
  

Equipment designed for different aircraft appliances control, aircraft connection with ATM systems and surveillance on air & ground situation is named as on-board electronic equipment (OBE) or avionics. Equipment that provides power supply (hydraulic systems, power supply systems), life support (air conditioning systems) and also land gear actuation, braking acquisition during landing and rejected takeoff is named as general aircraft equipment (GAE).

On-board equipment development determines the aviation development process in a great measure.

Aircraft evolution

Fig. 1.1. Aircraft evolution in the last 100 years.
The maiden controlled flight on a vehicle heavier than air was carried out in 1903. Since then aeronautics improved from the simplest flying machines, which where only designed for demonstration of the possibility to fly in aerial domain, up to the specialized multifunctional aircraft performing passenger and cargo carriage, combat and special missions.

There were about one thousand aircraft in 1912, by 2012 there were about 28000 aircraft.

Aviation development initial period was connected with global problems solving of aerodynamics, construction materials and engine power up. Hereafter, particular during the switching to jet thrust and supersonic flight, the role of the on-board equipment significantly has increased. The 21st century aviation is oriented for the revolution changes in the on-board equipment. It is connected, in the first place, with the fast development of electronics and innovation processes in informational systems. >>>

Fig. 1.2. Cockpit evolution in the last half a century.

>>> Cockpit evolution

With the development of aviation the human factor become more influencing at the flight safety.

The full and in-time awareness on flight conditions and aircraft status is a basic principle for the flight safety. An interface between the crew and complicated on-board equipment complex states the evolution of aircraft control and navigation instrumentation.

In XX century: there were electromechanical displays in 1940-1970x, certain electronic indicators appear in 1980x.

In XXI century: beginning of 2000x years — electronic indicators (glass cockpit), 2020-2040x — integrated electronic indication with 3D synthetic indication system of the «real» situation.

On-board equipment evolution

The growing number of parts and functions complexity of the on-board equipment has become a reason of certain appliances and devices transition to the on-board equipment complex, which is based on on-board computational systems.

The transition form the simplest analog computers to the on-board digital computational systems opened the wide road to the processes of on-board equipment and control functions integration that in turn provided the growth of equipment robustness despite the growth of complexity. >>>

Fig. 1.3. On-board complex evolution — from the separated devices to the IMA architecture.

>>> The Integrated modular avionics (IMA) allowed carrying over all the functions of management to the level of software. It supported the reverse engineering of computational system in a form of a standard modules limited number set.

In turn, implementation of real-time operation systems allowed building up software in a form of separate functional-programmable modules.

Hardware and software modularity is a key to the unification, standardization and as a result it reduces efforts in the development and production.

The simplest control circuit of the aircraft was presented by a compilation of drawing bars and walking beams which directly transmitted the deviation of control levers on the control surfaces of the aircraft. Electromechanical devices allowed tracking of the aircraft spatial position.

Fig. 1.4. Absence of the on-board equipment complex and the human dominant role in the aircraft control in the cockpit evolution early stages.

Partial automation of the piloting was achieved by introducing the simplest autopilot, which performed the altitude stabilization and improved the controllability of the aircraft.

Nevertheless, the dominant role of the human was saved in the piloting, flight management was conducted by the certain devices and the on-board equipment was not yet been formed at this stage. >>>

>>> The emergence of on-board equipment complex was connected with to the introduction of the special computer which formed the flight path and allowed solving tasks of the aircraft control on the path (flight management system — FMS).

The set of the controlling computer, devices and systems, united by a common purpose — aircraft control, became to be specified as the on-board equipment set (avionics).

Fig. 1.5. The growing role of the on-board equipment set in the aircraft control during the evolution from the centralized analogue to the federative digital on-board equipment set.

The first on-board sets had only one computational machine and were built on the centralized principle, based on the analogue computer.

Later, the set became based on a federal principle having several separated specialized computers. In addition, each control function was implemented in separate unit with a unified Electronic Flight Information System (EFIS).

The first federal on-board equipment sets were hybrid, because they contained both analogue and digital computational machines.

Subsequently, analogue calculators were completely replaced by digital one, using communication interface on the A-429 standard.

On-board equipment set having huge computational resources started the solving not only the control and indication tasks, but also tasks of the engine indication and crew alerting system (EICAS). The on-board equipment set role became the dominant in the flight management. >>>

Fig. 1.6. Upcoming issues of the federal on-board equipment set due to the quantity growing of digital units.

>>> The evolution of the federal on-board equipment set led to the fact that digital units installed on aircraft board has increased by 5 times for 20 years.

At the same time the software became more complicated. It caused the issues in software development and debugging.

The next issue was related with the different equipment integration into the single set. The «Electronic board» of each aircraft became the unique product which requires advanced system integration technologies.

Any expansion of control functions required the duplication of the system integration processes and system certification as all-in-all.

As a result of this approach all on-board equipment became more expensive, development time increased, complex reliability reduced, safety level lowered. >>>

Fig. 1.7. The foreign experience on the on-board equipment development in the last semi centenary.

>>> Foreign experience on on-board equipment set design

Specific span time analysis on AC design showed that 60% of time is spent for equipment development, although this parameter was about 20-30% in the middle of the last century.

As a result, the cost structure on software has changed and now is about 80% of on-board equipment set cost.

Now there is a growing need of the revolutionary change in the on-board equipment architecture.

Integrated Modular Avionics philosophy is believed to be a solution for this issue.