What’s New in Cockpit Avionics Safety?

What are the significant developments in avionics systems guiding aircraft? How does an assumption of safety underline these? Ken Elliott reviews...

Ken Elliott  |  03rd November 2017
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    Ken Elliott
    Ken Elliott

    Ken Elliott is a veteran with 52 years of aviation experience, focussed on avionics in General and Business...

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    Business Aircraft Avionics

    Advanced and Future Technology for Business Aviation, Part 1

    Ken Elliott examines significant developments in systems guiding aircraft from airport to airport, or on their missions. Behind each development is the baseline assumption of safety, underlining everything from design to full integration.

    Most of the NextGen advances under discussion are maturing today and could be implemented within a decade. Safety, however, and all that it influences will likely extend the migration of technology to over two decades. This assertion applies to both manned and unmanned platforms.

    There are three other factors impacting the timely introduction of advanced aviation technology. One is the enabled airspace, including ground and satellite infrastructure. A second is convincing investors to invest, and a third is reluctance to be an early adopter, for all sorts of good reasons.

    With reference to enabling airspace, there are four plans to help, including:

    • ICAO ASBU (Aviation System Block Upgrades)
    • Eurocontrol SESAR ATM (Air Traffic Management Master Plan)
    • FAA NextGen NSIP (NextGen Segmented Implementation Plan), and
    • FAA Drone Advisory Council (NASA-UTM & Centers of Excellence).

    A Different Perspective

    Today, in Business and General Aviation fixed wing operations we think of flying point-to-point. We measure an aircraft’s overall performance based on limitations of payload, range and time taken along a specific 3D path.

    Tomorrow, we will measure an aircraft’s overall performance, based on meeting assigned 4D predictability within payload, range and endurance limitations. 

    All airspace operations will be interdependent and fully integrated. They will include point-to-point and out-and-back flights, using manned, remote pilot and fully-autonomous operations, including within assigned classes of airspace, personal and for hire aircars.

    What enables all of this is:

    • Safety assessed and satisfied
    • 4D predictability
    • Total situational awareness
    • Alternative enduring propulsion
    • On-board systems moved to iCloud
    • Connectivity
    • Privacy and Security addressed
    • All-weather operations
    • Economical and user-adopted
    • An ability to recover.

    While a tall order, many of these areas are already being addressed at an exponential rate, in line with social and technological changes that are ongoing elsewhere in our lives.

    For Business and General Aviation, technology being developed for an improved flying experience should provide: 

    • Access and Predictability
    • An ability to fly operations as planned
    • A favorable ROI for mandated upgrades
    • An atmosphere of ‘do no harm’.

    Advanced Technologies

    For this article and its Part 2 follow-up, we will cover groups of advanced technology. Much of the equipment required for a planned future airspace is already in design or even being built. We can, in fact, assume that the technology is somewhat mature for most requirements, out to 2025. 

    Although the technology may be available, equipage rates are currently low. Even the upcoming requirement of ADS-B Out has had a slow uptake. For example, various versions of Performance Based Navigation (PBN) approaches (such as ‘RNP AR with RF legs’) cannot be flown by several air carrier aircraft because they lack the necessary equipment even though the procedures themselves are enabled.

    Most of the advanced technology to be covered—developments likely brewing in the ‘skunkworks’ department of product manufacturers today—apply to programs needed beyond 2025.

    Big Data

    As the title suggests, for big data think ‘Internet of Things’ (IoT) and iCloud computing. Figure A (below) depicts the five elements of ‘big data’ for aviation, which we will discuss more fully here. 

    01. Datalink:Controller Pilot Datalink Control (CPDLC) is the overall data link method, best articulated in ICAO’s Global Operational Datalink (GODL) manual. CPDLC applies to:

    • US digital departure clearances
    • Oceanic operations with FANS, including FANS Over Iridium
    • Europe’s delayed VDL Mode 2-Link 2000+
    • Other specific regional air traffic services. 

    As time progresses, these will blend into a truly global digital Air Traffic Network (ATN). In the US this is being evolved as ATN-B2 Data Comm.

    In the long term, Datalink will universally replace voice, an appropriate move, as we shift over to autonomy in aircraft platforms. 

    02. High Speed:Using 5G in our mobile networks, with an aircraft data transfer rate anticipated at 1G, aviation will slowly edge toward ground data transfer rates. Meanwhile in 2018 and for the US, SmartSky’s delayed 4G Air-to-Ground (ATG) network will provide up to 100Mbps speeds, above 10,000 ft. altitude.

    Satellite services, with global coverage, are creeping closer to these ATG rates as new platforms are launched. Inmarsat’s Jet ConneX provides up to 50Mbps (typically 15Mbps). 

    A bigger concern, especially for satellites, because of their distance from earth, is latency. This is the delay in data transfer that can represent an issue for users. Another concern is that of bandwidth limitation, controlling the amount of data you can cram into the frequency space allocated.

    Simply put, greater speed, wider bandwidth, reduced latency and affordability will advance the uptake of high speed data systems. 

    03. Different Methods:Data can be transferred between aircraft, and to and from the ground by several different methods. Based on the bandwidth and speed required, various methods include:

    • HF Datalink (HDL)
    • VHF Datalink (VDL)
    • Air to Ground LTE
    • Iridium low-earth orbit satellites
    • Inmarsat, ViaSat, and other high-earth orbit satellites.

    04. Aircraft Status:Monitoring and assessing the real-time status of aircraft is an exciting new field already established in Air Carrier aircraft and moving to Business Aviation. Flight departments are realizing the benefits and savings from the acquisition of virtual live streamed information from the aircraft. 

    Within the aircraft themselves, new devices are being developed to tap and send the information via Bluetooth nodes to a central server. The server streams the data to the ground via Satellite or ATG. Known as Wireless Avionics Intra Communications (WAIC), this technology is rapidly maturing as it is enabled by faster data transfer rates. 

    05. Flying Cabin:Initially, future aircraft platforms may emerge without windshields and later without cockpits. As virtual flying cabins, their data needs will be cabin centric for passenger flight. For passenger, freight and mission platforms alike, commands and ‘control loop feedback’ will be directed via iCloud to on-board flight control sensors and actuators. 

    In some ways the demands for data using iCloud will be much less, because most of the processing will be conducted off the aircraft itself.


    Best described as total situational awareness, surveillance addresses the need of the on-board crew, air traffic control and other aircraft to see and avoid. It includes tracking, recording and live display of aircraft position and trajectory, in relation to earth and other aircraft in its vicinity. Following, and illustrated in Figure B, we discuss six elements of surveillance for aviation… 

    01. ADS: Automatic Dependent Surveillance (ADS) comes in two versions, soon to be three, including: 

    • Broadcast (ADS-B), both Out and In
    • Contract (ADS-C) with FANS
    • Satellite (ADS-B) global coverage on the way.

    ADS is expanding into many more uses, including as a candidate for the unmanned ID solution being currently explored by the FAA’s Drone Advisory Council. 

    Aircraft will be tracked and identified wherever they are, for safety and recovery reasons, eventually mothballing the need for ELTs and Recorder beacons. ADS is also being demonstrated as a viable backup for some RVSM requirements, especially for compliance monitoring. As ADS-B, it is being used for In-Trail procedures.

    02. TCAS:Traffic Collision and Avoidance System (TCAS), has now evolved to level 7.1. It will continue to adapt further as aircraft operate simultaneously into parallel runways, and as more platforms enter the airspace.

    Eventually, TCAS will be a fully integrated subset of the upcoming Integrated Surveillance Solution (ISS). 

    03. TAWS:Terrain Awareness Warning System (TAWS) includes approach, runway and ground awareness. Increasingly embedded (along with map-based programs) in avionics display suites, TAWS will also become an integral part of ISS.

    04. Surface:Airborne systems using Personal Electronic Devices and moving map displays show the aircraft position on runways and taxi-ways for pilots. Meanwhile, ground-based systems provide air traffic controllers with an airport’s full situational awareness, including the movement of ground vehicles. 

    In the future, both in-air and ground awareness will be totally integrated, allowing users to select and focus on specific data needed to safely traverse the airport or manage aircraft movement.

    05. Single ISS:A single Integrated Surveillance System is on its way combining and back-checking multiple sensor inputs, while providing a single composite view to the pilot. Data provided will be live, dynamic and trajectory-based, allowing for satisfactory see and avoid, at a level suitable for unmanned see and avoid capability.

    ISS will grow to be concurrent with the integration of new aircraft platforms into the airspace.

    06. See, Avoid & Recover:See and avoid becomes more critical as technology compliments and supports the pilot. Today, a pilot’s responsibility is to see and avoid. Tomorrow, technology will assume that function to the extent it will command the aircraft to avoid other aircraft, terrain and obstacles. 

    Pilots today recover aircraft from uncommanded movement, but future generation aircraft will automatically attempt to recover via sensing, actuation and feedback mechanisms. 

    Time-Based Projection

    Providing for predictability, time-based projection ensures aircraft arrive at a fixed point in space (3D) at a specific time (4D). The speed, route and flight attitude of the aircraft are adjusted to ensure this requirement is met. Also known as metering, it ensures spacing, prevents bunching and dramatically improves traffic flow management (TFM). Five elements of time-based projection (see Figure C) are discussed here.

    01. PBN:Performance Based Navigation (PBN) allows the operator to select sensors and seek their specific operational approval to meet a navigation performance requirement. PBN routes are lateral deviation and no longer angular-based. Routes designed for PBN avoid noise sensitive areas and may allow a curved flight path as an aircraft approaches the airport. A Required Navigation Performance (RNP) limitation is specified to provide lateral tolerances, anywhere from 10nm down to 0.1nm of acceptable deviation off track.

    Advanced PBN will continue to accommodate more of the 4D aspects of navigation during all phases of flight. 

    02. Optimizing Flight Path: A flight path can be optimized by the aircraft’s ability to seamlessly transition between each phase of flight using procedures such as optimal profile descent (OPD), curved PBN approaches and ‘Established on RNP’ (EoR). However, we are still segmenting optimization at runways, terminal areas and en route.

    Eventually optimization will simultaneously accommodate multiple users between multiple airports, where despite some compromise everyone will benefit in some way. 

    03. Generating Trajectory:Generating a trajectory implies predictive flight and is a prerequisite for 4D navigation. There are many inputs to defining a trajectory as it integrates all airspace users within the immediate vicinity of each operator. Eventually, predictive trajectory must be consistently reliable and always precise.

    04. Time at Point: As depicted in Diagram A, reaching a point in space at a specific time, while accommodating multiple user platforms, can be a real challenge. It requires careful metering and almost demands total automation of air traffic control. Deliberate human responses may simply be too slow. 

    Multiple mission types and a higher count of aircraft operating in the same airspace, equates to more control needed to maintain flexibility. This includes accommodating sudden, but necessary, changes of flight plans.

    05. Tactical Adjustment:Ultimately, operating the optimum aircraft trajectory within regulated airspace will require moment-by-moment fine tuning. Each aircraft will require an autonomous and continuous adjustment of speed, position and its trajectory to safely fly with reliable predictability. The future cloud, or whatever it becomes, will manage all of that…but it is a long way off. 

    Flight Execution

    Put another way, flying the flight plan as filed is satisfactory flight execution. However, several factors influence an ability to complete a flight as planned, including: 

    • Weather
    • Routing
    • Clearance delays
    • SUAs, including TFRs
    • Not equipped or operating MEL’d items
    • Personal delays and change of circumstance.

    These will be addressed by the introduction of advanced technologies, providing any solution is economical and readily embraced. Following we’ll discuss the five phases of flight execution, as represented by Figure D. 

    01. Taxi:A predictable execution of uninterrupted taxiing at major airports will require some finessing. Manually accomplished today, it will need to be automated tomorrow. There will always be construction, storms and icy surfaces to hamper ground operations, but airports are advancing rapidly regarding technology. 

    It should always be borne in mind that realizing a satisfactory flight begins and ends at the ramp—not at the runway end—especially at busy commercial airports. 

    02. Departure: With Datalink departure clearance at major US commercial airports, we are on the way to fully automated departures everywhere a clearance is required. Metered taxi and take-off on parallel runways is also in work.

    03. Cruise: Predicting arrivals at designated points in space will ensure reliable en route traffic flow. Routes are becoming more direct and better able to accommodate requests to operate at fuel efficient flight levels.

    04. Arrival: Arrival improvements, from a navigational perspective, have been huge for Business and General Aviation. Today, this community is predominantly equipped for WAAS-LPV approaches, where satellites guide an aircraft down to relatively low minimum decision altitudes. Now, with multiple choices for approaches into runways at ILS and non-ILS airports alike, there is a greater likelihood of flying as filed. 

    05. Land (and Taxi): If you can’t land, you may as well not take off! Complying with the last part of an approach to land where rules for visual cues apply can be a challenge in low visibility conditions. Current and future solutions, using GPS-Based Approach Systems (GBAS) and On-Board Enhanced Flight Vision Systems (EFVS) are expensive to employ.

    Because of advancing technology, costs are now tumbling down, at least for EFVS where new rules are performance-based and equipage needs met using small, light HUDs and multi-spectral cameras.

    The goal of the FAA’s new FAR Part 91-176 rule is to provide an ability to operate as virtual VFR, using eye equivalent technology during zero RVR, and zero height above the runway, to land during low visibility conditions. This ultimate goal is several years away. Certified technology still needs to catch up to the rule. 


    The introduction of new aviation technology will not advance if redundancy is not adequately built in and assured. This becomes increasingly relevant as remote pilot and autonomous operations emerge. Following, we discuss the six elements of technology redundancy in aircraft, as represented in Figure E.

    01. Duplication:A common practice for aviation equipage is duplication, where safety and reliability of flight is paramount. There are usually two communication transceivers, two navigation transceivers and so on. Even as we transition from on-board hardware to ‘processing in the cloud’, duplication will still be necessary and yet easier to accomplish.

    02. Alternate:Instead of (or as well as) duplication there are alternates in equipment necessary to safely and reliably execute flights. An example is the ability to use DME-DME (Rho-Rho) for dedicated approaches that do not employ the aircraft’s navigation transceivers.

    DME is a secure alternate to vulnerable GPS. Equally, HF communication may still be used in place of Satcom for Oceanic communication. As with duplication, the future will be no different in concept regarding alternate means of compliance. 

    03. Single Point of Failure:Regulators look closely at aircraft during certifications to check there is no single point of failure that can be considered catastrophic. Risk mitigation in the design of an aircraft and its systems is paramount to safety and will never be compromised as technology advances, including remote pilot and autonomous flight.

    04. Loss of Lock:This is all about control. The specific term “lock” is currently applied to unmanned, remotely piloted operations, where the signal between the pilot on the ground and the drone in the sky must remain continuously locked on. However, if an on-board flight crew lose the ability to control a fixed or rotary wing aircraft, it can also be construed as a version of loss of lock.

    Losing lock is also tied to recovery, where the aircraft must re-engage its intended attitude and flight track. The ability of future air vehicles to be allowed to operate in regulated airspace is fully dependent on reliably maintaining signal lock. 

    05. Virtual: A duplicate virtual aircraft is a future redundancy capability that performs like an aircraft in a simulator, functioning with realistic versions of the environment, including weather. It also implies that the aircraft equipage (as sensors, processors and transmitters) is existing and operating in a Cloud.

    The Cloud, in turn, commands multiple actuators in the aircraft to alter the vehicle’s movement, as a redundancy back-up to a primary system failure. The same ‘cloud-aircraft’ also records historical performance and trajectory. 

    06. Ground & Air:Of course, improvements in technology apply equally to both air and ground functionality. Aircraft, space and ground technology should all advance in step. An outdated air traffic system is not conducive to the future of aviation. Equally, air traffic control needs to be user-agnostic and not operated by those with special interests. 

    The complexity of air traffic to come requires an independent, equitable and “best-equipped, best-served approach”, to match the rapid advances taking place in the aircraft themselves.

    We will continue our discussion of Future and Advanced avionics technology in the December edition of AvBuyer. Stay tuned!

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