A Review of Recommended and Required BizAv Avionics

Ken Elliott provides an overview for owners and operators needing to know more about recommended and required avionics for their business aircraft today.

Ken Elliott  |  30th May 2022
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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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    Private jet cockpit with snow-covered mountains outside window

    When considering the ‘recommended’ and ‘required’ avionics for business airplanes, it’s important to understand that ‘required’ can have different connotations based on which aircraft you own, or where and how you operate. Similarly, ‘recommended’ can have a different emphasis for different aircraft owners, based on individual priorities, both as a corporation and a flight department.

    Knowing what you need, why, and how, can be very confusing, and the issue of complexity arises both in the avionics themselves, and the differing applications of aircraft integration, only adding to the confusion.

    The Complexity Issue and Solutions

    The last significant requirement for aircraft was ADS-B Out. It impacted most aircraft across most of the planet. There were regional differences in both technical (ADS-B Out Version 1 and 2) and operational (aircraft and airspace application) requirements.

    In most cases, the requirement itself was straightforward, and flight departments quickly grasped the need to comply by a mandated deadline. However, for each aircraft, there was the possibility of complexity to creep into the installation, and this is where things became interesting.

    ADS-B Out relies heavily on transponders and flight management systems. These products needed to be at a certain level of capability to handle the function of automatic dependent surveillance, and many that were in operation were far from it. For numerous aircraft owners it was a surprise to discover their aircraft equipment needed to be upgraded or replaced to enable ADS-B Out operation.

    Creative solutions for older business jets and turboprops emerged from unlikely places, and one – CMD Flight Solutions – stands out. CMD developed a long list of AML STCs (Approved Model List, Supplemental Type Certificates), enabling a specific solution to be applied to multiple models of aircraft.

    Furthermore, the STC could be purchased and installed by competing facilities. The example of ADS-B Out is very important to this article as it sheds light into the complexity of avionics upgrades, as mandated, required, recommended, or simply desired.

    The creativity of the solution emerges from a need to marry a new technology to existing technology, without replacing everything. It also reveals itself in the application of one solution across many different aircraft, sharing and reducing the non-recoverable engineering (NRE) cost.

    This same creativity throughout the avionics industry provides multiple solutions for the same upgrade across various avionics systems. Owners of pre-owned business jets and turboprops may find an answer to their dilemma of ‘cost versus benefit’, or ‘return on investment’ (ROI), in searching for, and locating, a creative and sometimes alternate solution to the one being promoted by the Original Equipment Manufacturer (OEM).

    So, as a useful tip, when researching and preparing for any avionics change, always ask your avionics shop for the complete range of options available to you. Familiarize yourself with terms such as:

    • Third party solutions
    • STCs and AML STCs
    • Software and hardware versions of avionics equipment (boxes, modules, cards)
    • Exchanges, loaners and factory modifications.

    Some solutions are new and novel, and will require shopping around to locate. But, when the next mandate or recommendation comes along, there should be a solution to fit your budget somewhere.

    Mandates, Requirements and Recommendations

    When airworthiness authorities issue equipage requirements for aircraft, they are commonly referred to as mandates. Typically, the authority will prepare the infrastructure and operating parameters, and then settle on a rule(s) with a deadline(s), to apply to all the affected aircraft.

    However, for operators, mandates are only part of how they experience requirements. An average flight department also needs to consider where they are operating, ownership needs, passenger needs, and maintaining aircraft currency. In a sense these can all be considered requirements or, at the very least, recommendations.

    Mandated: Since about 1998 the business aircraft industry has faced several mandates, many of which applied to most operators. Following are the primary mandates for avionics equipage on a typical corporate aircraft:

    1. 1.    8.33 KHz Communications and FM immunity for Navigation equipment
      2.    Terrain Awareness Warning Systems (TAWS), including Honeywell trademarked EGPWS
      3.    Traffic Collision Avoidance System (TCAS). Versions included TAS, TCAS 1, and TCAS II (with its latest version being 7.1)
      4.    Emergency Locator Transmitter (ELT), including versions with 406MHz capability
      5.    Reduced Vertical Separation Minimums (RVSM)
      6.    Automatic Dependent Surveillance – Broadcast, Out (ADS-B Out). This is required to be Version 2 for most regions.

    Regional Required: While you still need to comply with all the mandates, there are secondary required avionics, based on where you intend to operate. This may be specified by region or by airspace limits, such as altitude or flight tracks.

    1. Controller Pilot Data Link Communications – VHF Data Link Mode 2 (CPDLC-VDL Mode 2) in Europe.
    2. Controller Pilot Data Link Communications – Future Air Navigation System (FANS) Oceanic and Remote. FANS impacts several avionics systems, including data capability on your existing cockpit voice recorder. It also may involve considerable expense, such as adding a compatible Satcom.
    3. Flight Data Recorder (FDR). Even though you may have one, it may not have sufficient or required data labels from across your aircraft systems.

    Optional Required: Then there are the optional required avionics that will enable fuel savings, performance improvements, greater access, and all-weather operations. What dictates ‘optional required’ is that you can choose to do without them, but if you want to operate in certain advantageous ways you will need to equip. Examples include:

    1. Departure Clearance (DCL): Being embraced by commercial operators at specific airports and runways, and utilized by business and other aircraft too, in the long-term data will replace voice everywhere.
    2. Wide Area Augmentation System- Lateral Path or Lateral Path Vertical (WAAS-LP/LPV): Optional navigational approaches, or actual approaches, at specific runways. LP is equivalent to a Localizer only, and LPV is equivalent to both Localizer and Glidepath.
    3. Quick Access Recorders: For data recording to meet monitoring requirements and engine manufacturer support programs.
    4. Enhanced Flight Vision Systems – EFVS (requiring both a Head-Up Display and EVS): Enables operations to lower minimums in degraded visibility (runway visual range-RVR). Expect EFVS to be expanded, to include Synthetic Vision Systems (SVS).

    In summary, there are mandated, required to operate and optional required avionics for operators to consider. Typically, ‘optional required’ implies that popular alternate means of operating on that specific leg of the flight still exist.

    Beyond ‘mandated’ and ‘required’ are the ‘electable’, or recommended. Those avionic systems may be elected for all sorts of reasons, but are not specifically required to operate in an individual region, airspace or airport.

    Examples include ADS-B In, Electronics Flight Bags (EFB), Moving Maps-Electronic Charts, Air-to-Ground Internet and Satellite Internet.

    Current and Upcoming Avionics Requirements

    Requirements for avionics equipage and upgrades are forever evolving, and deadline dates will often shift to the right. With that in mind, there are several current and upcoming requirements to consider.

    Table A (below) is a quick reference guide to ‘requirements’, and separates the different interpretations of ‘required’. The table mostly uses acronyms and is designed as a checklist to check against your aircraft equipage, and for consultation with your preferred avionics shop. Keep in mind that there are regional applications of these requirements such as with ADS-B Out, or with CVR-FDR. A good source for checking mandate requirements is the National Business Aviation Association (NBAA) or EASA (for Europe) and ICAO (worldwide).

    Avionics Requirements: Take Note

    The following information is worth taking note of, regarding requirements that apply to avionics in business jets and turboprops...

    Repair versus Replacement

    Although not a requirement for avionics from a flight department perspective, there will be some incidents where a decision to replace an instrument may be a necessity, and therefore a requirement.

    Repairs always involve some measure of hassle, such as the loss of valuable time while the logistics are taken care of. It could be that a ‘loaner’ item of avionics is required, or an exchange that may have more flight hours than the failed unit had.

    Repairs can be frustrating not only because of the cost, but also the frequency. Repeated activity due to the same fault reoccurring will increase downtime and operating costs. And repeated removal and reinstallation of interiors for access to faulty avionics is another factor that adds to wear and tear on the aircraft.

    All the issues around repairs feed into a decision to replace. The replacement is usually a form of upgrade, and may add new features into the cockpit or cabin. Flight departments can do due diligence on repair versus replacement decisions, but keep in mind there are some less obvious factors that may impact resale, either negatively or positively.

    One negative could be repeated repair entries in logbooks, causing buyers to become suspicious. Conversely, upgraded avionics could be the differentiator between two offerings of the same aircraft type.

    Radio Altimeters and 5G Signals

    The situation regarding the use of existing radio altimeters at 87 US airport regions where 5G internet is being deployed ‘is in development’.

    In a nutshell, one the frequencies used in 5G deployment can potentially interfere with radio altimeters on aircraft. Because these altimeters are so integrated with primary aircraft systems, such as TCAS, TAWS, Autopilots, ILS, Autoland and HUDs, there are obvious concerns about any possibility for interference.

    Unlike altimeters that are based on sea level and barometric pressure, radio altimeters measure height above terrain (HAT) or above ground level (AGL), and function from 2,500ft down. This implies their use in critical flight locations, such as around airports, or close to mountains.

    When radio altimeters were designed in the 1900s, and even when standards were revised in 2012, the frequency band they used was not adjacent to any other in wide use. 5G changed that.

    Because solutions are in work, one can only speculate on new standards being developed (via RTCA SAC239 and EUROCAE WG119), new or modified radio altimeters, or the installation of inline filters.

    There is likely to be some requirement for most corporate operators, even if they are unlikely to operate in and out of the current 87 sources of potential 5G interference. Meanwhile the FAA has issued ADs and other communications (see faa.org/5G), including AD 2021-23-12 (transport aircraft), and AD 2021-23-13 (helicopters), to facilitate the ongoing situation.

    DME as the GPS Back-up

    For some time, the aviation industry has been concerned with the vulnerability of GPS, used for navigation and position data in ELTs, ADS-B Out and other systems. This concern has taken on new meaning, and has strengthened due to recent conflicts.

    Having some form of reliable and existing back-up for GPS is essential in today’s environment, and the only accurate and available alternate technology is Distance Measuring Equipment (DME). Laseref gyros, as inertial navigation, are accurate over time and distance, and also can be employed as a backup navigation source for long flights when GPS is denied.

    By having multiple DME stations providing position information, an aircraft can determine a precise moving location and navigate. The legacy VOR-DME provides Rho-Theta navigation, while DME-DME provides Rho-Rho with less error. DME-DME can be used to bring the aircraft close into the airport, and throughout short flights.

    Look out for some recommendations involving improved DME that, apart from more ground stations, will upgrade the current dual systems installed in corporate aircraft today.

    Anti-Jamming and Interference

    Equipping aircraft with interference protection is often talked about but not acted upon. Most attention will focus on satellite and other infrastructure protection, but avionics can still have their own vulnerabilities to jamming, hacking, or interfering.

    Expect to see various novel solutions being required or recommended for business aircraft avionics over the next decade. Product manufacturers, both aircraft and equipment, will develop software, filtering, and hardware protective circuitry as upgrades to existing equipment, wiring, antennas, and accessories.

    Aircraft Tracking

    Aircraft are reliably tracked over continents and regular air corridors, but should they stray from the route there is less automated tracking available. Some systems are available to install, and they provide real-time position data to flight departments and could be useful in an emergency.

    Several different solutions are meeting ‘in the middle’ to address around-the-clock ‘anywhere’ aircraft tracking, not least satellite-based ADS-B from providers such as Aireon. Today this capability is optional, but it may become a requirement – or just evolve as a natural popular service – in the future.

    In Summary

    The purpose of this article was to address recommended and required avionics. It has been shown that apart from mandates that apply to widespread airspace users, what is merely recommended for one operator may be conceived as required by another.

    It is also apparent that optional avionics can suddenly become a requirement for a specific operator who needs to fly within a classified regional airspace.

    Knowing that, operators should always be vigilant across the complete avionics spectrum, where changes occur regularly. They can also have comfort in knowing that even if their aircraft is a vintage pre-owned model, someone, somewhere, will have created a solution just for them. Situations like obsolescence and repeat repairs can shift an optional upgrade to a required one, so it will be prudent for flight departments and owners to remain current on available products in general, and their own aircraft avionics in particular.

    As the world situation shifts like sand beneath our feet, it is likely that changes to avionics, that we cannot accurately foresee, may occur. Some of the noteworthy requirement commentary alludes to future changes that, in the end, may turn out to be very different to that shown.

    Avionics shops, major MROs, the leading aviation associations, and others are keen to support this evolving industry at all levels. Always consult with others while completing due diligence, before making a final decision on meeting avionics mandates, requirements, recommendation, or ‘a compelling option’.

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