Modern tools can lead to modern problems. While cathode-ray tubes, multi-function displays, and liquid-crystal displays have replaced the gyroscope and vacuum-powered avionics of yesteryear, pilots today need to be adaptable when the screens of information that make up the ‘glass cockpit’ of their modern airliners go dark. Thanks to the evolution of instruments that now provide pilots with enhanced situational awareness about both the progression of precision flight and technological health of their aircraft, aircrew of the 21st century need to be prepared to fly when information on their screens is absent during failures of avionics. Abdelmagid Bouzougarh, Chief Executive Officer of Aerviva, an international aviation recruitment consultancy, explains how sophisticated flight systems require training to ensure crew confidence during complex avionics failures.

According to Bouzougarh, the flight deck layout consists of multiple displays, each supported by redundant systems. For example, the primary flight display receives data from the Air Data Attitude Reference System (ADAHRS), which uses various subsystems to generate the information shown on the screen. While each aircraft may differ slightly, an ADAHRS typically gathers data from pitot-static ports and angle of attack sensors, which is processed by an Air Data Computer (ADC) to provide airspeed and attitude readings. Each display, along with its systems and subsystems, has potential failure points and corresponding procedures to handle such issues.

“Every aircraft will feature redundancy of vital systems as a part of its design, and certified avionics will have features to prevent a total loss of information given to the aircrew, which makes failures that result in screens going blank are extremely rare,” Bouzougarh says. “However, given the level of complexity of these systems, a failure of any one part of the systems that compose avionics can create unique situations that require a specific response depending on the failure that the crew diagnose and train for.”

In the example of altitude or airspeed, aircrew will be able to resolve issues by switching from one ADAHRS to the other, or to the ADC to recover those functions. However, each aircraft will have differences in its systems.  For example, on the Boeing 787, the primary flight display can change from pitot/static sources for airspeed and altimeter to angle of attack and GPS sources, which allows entirely different sensors to provide information should one sensor fail.

While advancements in technology over the past 20 years mean that the flight deck of the most popular aircraft types have become primarily electronic screens displaying a breathtaking amount of information and situational awareness, the opposite holds true when these systems fail. When the computer systems managing avionics fail, the screens go dark, leaving pilots without the information on which they depend to fly their aircraft. Bouzougarh notes air traffic control can assist by providing directional guidance when aircrew lose flight management computers.

“If an aircrew loses both flight management computers which feed the desired flight path to the aircraft’s navigation systems, radar-vectoring from air traffic control can offer directional guidance,” he says. “Regardless of the technology and aircraft type where the avionics failure occurs, crewmember ability to confront these problems will depend upon their level of education on aircraft systems, practical experience, licenses, medical certificate, flight hours, simulator training.”

Bouzougarh added that regulators such as the European Union Aviation Safety Agency (EASA) creates syllabuses for avionic failure study. Adherence to the training syllabus will change depending on flight center, and the aviation safety experts are continuously changing regulations and reviewing case-studies on their failures to refine the training required to qualify pilots.

However, certain situations do require more training to ensure that if avionics failures were to happen, there are checklists in the quick reference handbooks that guide pilots through the appropriate actions. Such reference books and checklists will need to be run through while pilots fly on less capable standby instruments that provide redundancy at the cost of taking up less space or being less user friendly.

During these failures, crews will need to have good checklist use and CRM during simulator practice to demonstrate capability to their airlines and regulators. “Annual recurrent training includes practicing with standby instruments during failures,” Bouzougarh says. “Simulator time allows students to use diminished capability standby instruments to practice diverting, should that occur in flight.”

Bouzougarh explains that pilots need to be able to fly precisely, using a certain set of instrument landing approach procedures, on a 3“ square standby display.

“These events are rare, but they have been known to take place on almost every airline and aircraft type,” he says. “While the debate over the reliability of new technology is well established, the design of aircraft to feature increasingly sophisticated systems changes how pilots interact with avionics failures.“