All systems under control

How to make sure avionics devices and systems meet the strictest requirements

By Claire Marchand

Avionics - a term coined from the merging of aviation and electronics - deals with all electronic devices and systems that perform specific individual functions on aircraft, satellites and spacecraft.

Spitfire cockpit Analog dials and gauges in the cockpit of a Spitfire, a fighter aircraft used by the Royal Air Force and Allied countries during WW II (Spit 'n Bailing Wire Blog)

From WW II fighter planes to state of the art aircraft

Modern avionics systems have their origin in World War II technological advances. This is the case for autopilot systems, for instance, which today equip any type of aircraft, from the smallest to the biggest passenger or cargo plane, and were developed during the war to help bomber planes fly steadily enough at high altitudes to hit their targets with precision. The radar was another engineering development of that era. 

Post-WW II developments often continue to have their origin in the military, where a fair portion of the spending is allocated to avionics. In addition to benefitting from the new technologies trickling down from the defense industry, civil aviation has also seen a growing part of its R&D budget devoted to aircraft control systems and the like. 

The second half of the 20th century saw very important breakthroughs in the electronics industry. These in turn had a major impact on the avionics sector which grew at a rapid pace. While new developments were usually made for the military and/or the space industry, they soon made their way into civil and commercial aviation as well. 

In addition, the democratization of consumer flying followed by the emergence of low-cost airlines increased air traffic, tighter airspaces and, consequently, the need for more sophisticated methods of controlling and ensuring aircraft and passenger safety. 

The cockpit, a concentration of avionics

The cockpit of an aircraft is a typical location for avionic equipment that consists of control, monitoring, communication, navigation, weather, and anti-collision systems. They include: 

  • Automatic control
    Automatic flight control systems lighten the pilots’ workload, especially at crucial times such as landing or when hovering, and help eliminate human errors that might otherwise prove fatal.
  • Monitoring
    Display systems provide sensor data that allow the pilots to monitor flight parameters at all times and thus to fly the aircraft safely. Most of the information that used to be displayed on mechanical gauges in older aircraft now appears on electronic displays.
  • Communications
    Communications connect the flight deck to the ground and to the passengers. On-board communications are provided by public address systems and aircraft intercoms.
  • Navigation
    Navigation is the determination of position and heading (direction) on or above the surface of the earth. Avionics can use satellite-based systems, ground-based systems, or any combination of the two. Navigation systems calculate the position automatically and display it to the flight crew on moving map displays.
  • Anti-collision systems
    As a complement to air traffic control, most large transport aircraft and many smaller ones use a traffic alert and collision avoidance system (TCAS), which can detect the location of nearby aircraft and provide instructions for avoiding a mid-air collision. Smaller aircraft may use simpler traffic alert systems which are passive and do not provide information for resolving potential problems. To help avoid collision with terrain, aircraft have systems such as ground-proximity warning systems (GPWS), of which radar altimeters are a key element.
  • Weather
    Weather instrumentation, such as radar and lightning detectors, is important for aircraft which fly at night or in meteorological conditions in which pilots cannot see the weather ahead. Heavy precipitation (as sensed by radar) or severe turbulence (as sensed by lightning activity) are indicators of severe disturbances, and these weather instruments allow pilots to deviate around such areas.
  • Aircraft management systems
    The trend today is to have centralized control of the multiple complex systems fitted to aircraft, including engine monitoring and management.

Specific requirements for avionics

While in the early days, a whole branch of the electronics sector designed and manufactured electronic components specifically for the aerospace/military industry, avionics today is mainly dependent on commercial off-the-shelf (COTS) electronic components. These are principally mainstream products, designed for all industries including consumer goods. But avionics has to meet its own requirements in terms of performance and durability. 

IEC International Standards...

Although they may be subjected to severe conditions such as the possible negative effects of atmospheric radiation at high altitude, or temperatures that may be outside the range specified for semiconductor devices by their manufacturers, avionics products must still perform reliably and safely during their working life. 

IEC Technical Committee (TC) 107 develops process management Standards for these and other issues. Avionics original equipment manufacturers (OEMs) use increasing volumes of COTS electronic components, equipment and systems designed and manufactured for other industries in which they have limited control. 

Many countries and regions are adopting legislation that restricts or eliminates the use of substances containing lead in most electrical and electronic equipment. As the avionics industry relies on COTS components, TC 107 provides a lead-free control plan that allows manufacturers to check the reliability of the components they use. 

TC 107 also provides guidance for the avoidance, detection and mitigation of counterfeit electronic parts in avionics applications. 

Other IEC TCs, such as TC 47: Semiconductor devices, or TC 110: Electronic display devices, prepare International Standards for components used in avionics applications. 

...and certification crucial for avionics

IECQ, the IEC Quality Assessment System for Electronic Components, takes it one step further, testing and certifying the widest variety of electronic components. In addition, IECQ has a programme specifically designed for avionics, the IECQ Avionics Scheme

The IECQ avionics parts and assembly management requirements are designed to evaluate commercial, military and aerospace equipment manufacturers’ and related organizations’ processes for compliance with the following Standards:

  • IEC TS 62239-1, Process management for avionics – Management plan – Part 1: Preparation and maintenance of an electronic components management plan, developed by TC 107, and/or
  • GEIA/ANSI 4899, Requirements for an Electronic Components Management Plan 

Organizations holding IECQ avionics certification demonstrate that their organization and facilities comply with the requirements of the IECQ System and either IEC TS 62239-1 or GEIA/ANSI 4899 for their scope of activity. 

Meeting all challenges

Electronic component manufacturers have other IECQ Schemes at their disposal to address counterfeit and hazardous substance issues.

IECQ has a Counterfeit Avoidance Programme (IECQ CAP) which ensures that equipment manufacturers or subcontractors used by an organization have processes for managing counterfeit avoidance in the selection and use of components according to IECQ CAP technical and quality management system requirements. 

The IECQ Hazardous Substance Process Management (HSPM) Scheme is a technically based management systems approach to implementing and maintaining hazardous substance free products and production processes. IECQ HSPM was developed in response to component manufacturers’ needs to give suppliers the means of demonstrating, through third-party assessment, that their electrical and electronic components and assemblies meet specific hazardous substance- free local, national and international requirements. 

For more information on IECQ and its Schemes www.iecq.org

Gallery
Airbus A380 cockpit The flight deck of an Airbus A380 (Photo: Naddsy/Wikimedia Commons)
Spitfire cockpit Analog dials and gauges in the cockpit of a Spitfire, a fighter aircraft used by the Royal Air Force and Allied countries during WW II (Spit 'n Bailing Wire Blog)
ULA Vulcan Centaur rocket United Launch Alliance (ULA)’s Vulcan Centaur rocket with a complete avionics package developed by L3. (Photo rendering: ULA/Business Wire)