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An IPS Roadmap for Aeronautical Safety Services

The world’s two largest commercial airframe OEMs are evaluating the inclusion of Internet Protocol Suite (IPS) technology as a line-fit solution on their aircraft once standards for a new IP-based network infrastructure arise. These are the latest developments around how civil aviation regulators, avionics suppliers, air-to-ground data link equipment providers, and more are in the earliest stages of developing IPS for air-to-ground, safety services data communications.

A new network infrastructure based on internet protocol that promises to use commercial-off-the-shelf (COTS) products to support air-to-ground aeronautical safety services communications is in its earliest stages of development, with a targeted operational date of 2024-2028.

ARINC Project Paper 658, first released in mid-2016 by the Airlines Electronic Engineering Committee (AEEC), provides the initial roadmap for establishing an Internet Protocol Suite (IPS) for aeronautical safety services. It defines considerations such as the avionics architectures of the 2000s and 2010s, integration of IP into ARINC 429 data bus and ARINC 664 avionics architectures as well as harmonization on sub-network data link usage internationally. It also addresses equipment used on aircraft by OEMs and on the ground by air navigation service providers (ANSPs), air traffic controllers, and data communications service providers.

While IP is already used for ground-to-ground sharing of packets of data about safety-critical information (like positioning, speed, and altitude), the air-to-ground portion of modern aircraft data communications is mostly unique to aviation.

The thinking behind IPS is that it can foster the move toward broad use of multiple data links on aircraft to support sharing of communications, navigation, and surveillance information under Air Traffic Management (ATM) modernization programs like the FAA’s NextGen program, Europe’s Single European Sky ATM Research (SESAR) program and Japan’s Collaborative Actions for Renovation of Air Traffic Systems (CARATS) program. Middle Eastern ANSPs have also held meetings with ICAO in recent years to discuss how they can upgrade their ATM infrastructure.

ICAO’s 20-year Aviation System Block Upgrades (ASBU) plan focuses on four main areas: airport operations, globally interoperable systems and data, optimum capacity and flexible flights, and efficient flight paths. IPS is being discussed as a way to offer a new sub-network for the exchange of safety-critical data and flight information between aircraft and ground automation systems, as well as to expand the bandwidth, spectrum and sub-network multi-link availability needed to support future air traffic growth projections.

Avionics and Air-to-Ground Data Links

Regarding the ground systems and air-to-ground data link communications portion of IPS, the ARINC project paper refers to the Aeronautical Communications, Addressing, and Reporting System (ACARS) global, digital air-to-ground communications system that supports transmission of short messages between aircraft and ground stations via airband radio or satellite on a subscription basis for commercial airlines. It says ACARS supports an air-to-ground communications protocol per ARINC 618 that can exchange messages no larger than 3.5 kilobytes, although the system has evolved to support multiple sub-networks, such as Very-High-Definition Data Link Mode 2 (VDL Mode 2), satcom and high-frequency data link.

“When IPS is deployed, it may be necessary for aircraft equipage to support both networks (“dual-stack”), similar to current equipage with ACARS and Open System Interconnection (OSI), since ACARS use is expected to continue beyond 2025,” the project paper says.

Furthermore, the roadmap foresees aircraft radios and routers evolving to support air-to-ground data link messages that are larger than 3.5 kilobytes so that ATM can move to time-based operations and Performance-Based Navigation (PBN) and Global Navigation Satellite System (GNSS) procedures can occur with more precision, allowing such advanced concepts as aircraft effectively landing themselves on curved approaches.

On the ground-to-ground side, though, ground automation technology that captures the bytes of data sent in packets by aircraft routers and radios is already using IP, according to Joel Otto, vice president of strategy and business development, for the Information Management Solutions (IMS) division of Rockwell Collins.

“When we think of IPS, we think of it as that next natural step in evolution in increment to what’s already being done for those safety services,” Otto says. “We don’t necessarily see it as something that is really all that new and different. Our networks today use IP for the ground-to-ground segments and deliver the traffic to the ANSPs. Having the air-to-ground segment move to IP and adding the suites and services on top of it, for us, is something that we think we’re going to be really well positioned to accommodate in the 2024-2028 timeframe, depending on who decides to implement it when.”

IPS concept of operations. Courtesy of Rockwell Collins.

Rockwell Collins holds a unique position in terms of IPS because of its acquisition of the ARINC global aeronautical services infrastructure in 2013. It also manufactures aircraft radio and router equipment, as well as flight management systems, touchscreen cockpit displays and other current and next-generation flight deck hardware and software. Otto said he believes that IP can be leveraged in aeronautical safety services in the same way that has made it ubiquitous in all commercial industries’ use of information services technology.

ANSPs and air traffic control technology companies and organizations are also showing increased interest in IPS, says Santi Ibarz, research and development director for Airtel ATN, a provider of air-to-ground data link servers, front end processors, and ground-to-ground routers for ANSPs. Airtel ATN works with Eurocontrol and European ANSPs like the Danish ANSP Naviair, Nav-Portugal and Italy’s ENAV to implement ground automation systems that will need to adopt new air-to-ground protocols to accommodate IPS. Ibarz says the company already is seeing demand for the technology from ANSPs in Europe.

“Airtel was involved in IPS when the standard was first written and considered for the industry 10-15 years ago,” he says, noting that at that time IPS was never validated in any flight trials or given real consideration for use in air-to-ground data links used for safety-critical aircraft data.

Since then, many considerations have arisen concerning a shift to air-to-ground IPS. These include cybersecurity issues and which protocols and technologies ANSPs can use (and when) that will ensure they can continue supporting links like VDL Mode O/A, and Aeronautical Mobile Airport Communications System (AeroMACS), future satcom systems, and L-band Digital Aeronautical Communications System (LDACS), and possibly VDL Mode 2. It is expected that IPS will also provide backward compatibility with traditional ACARS air traffic services (e.g., Future Air Navigation System) and Aeronautical Operational Control (AOC), such as ARINC 702A flight plans, as well as Link 2000+ (Aeronautical Telecommunication Network B1) and ATN B2 applications.

“Our ground customers, ATC customers are asking us, what about IPS?” says Ibarz. “ANSPs want to know what technology to choose and when to upgrade to IPS, because the ground systems have to accommodate both the legacy and existing air-to-ground data link protocols, equipment and message sets on in-production aircraft for another 20 years. They’ll have to be able to be interoperable with the new aircraft that will eventually have IPS in the future. That’s where the interest from our ground customers comes from. They’re trying to understand and build their own roadmaps as to when they’re going to need to upgrade to this new technology.”

Airbus, Boeing IPS R&D

Airbus and Boeing are both evaluating the prospects of including IPS as a line-fit solution on their aircraft once standards for an IP-based network infrastructure are established. Airbus noted that it has not yet defined its technology roadmap. Boeing told Avionics Magazine that it intends to provide IPS for forward fit on aircraft, although it will look to make any specific decisions after the standards mature.

The long life span of Airbus and Boeing airframes is another element of the commercial air transportation and ATM ecosystem. Both companies have order backlogs that would take their production through 2023-2024.

The way ARINC Project Paper 658 outlines a path to IPS is beneficial to the long life span of airframes, because step 2 specifically states that an ARINC standard is being developed to define the avionics architecture and functions, as well as an IPS profile that will describe implementation options and constraints and higher-level details regarding the accommodation of different applications. Furthermore, the roadmap states that the standard will define the Communications Management Unit’s (CMU) ability to act as an IP router.

“Moving to IPS will simplify avionics by unifying the communication protocols from the current multi-stack architectures,” says Greg Saccone, research and technology senior systems engineer and associate technical fellow at Boeing.

Saccone believes that as ATM modernization programs progress in the U.S., Europe, Japan, and elsewhere, more and more data will be exchanged between the aircraft and ground systems, moving beyond the bandwidth of current communication protocols (which he says do not provide favorable compatibility with broadband applications).

“IPS will accommodate current applications while providing a transition path to more data-intensive applications of the future,” says Saccone. “ICAO, the FAA, and Europe all agree that the end goal is to move to IPS-based services. Boeing thinks that moving towards this end goal now, especially given the long lead time in developing standards, avionics, and ground systems, is a better spend of resources than continuing to try to extend the lifetime of outdated legacy technologies. Boeing is planning its research and product development accordingly.”

Saccone says that research will include more work on flight trials of IPS over VDL Mode 2, extensive satellite performance characterization, and trade studies in areas like mobility, security, and multiple-link support. He says Boeing also will look to expand partnerships for additional research in IPS.

The world’s two largest commercial aviation OEMs work together in many ways. Airbus and Boeing are actively involved in the AEEC IPS subcommittee, one of many on which the two sit together and negotiate over how safety-critical air-to-ground data link communications protocols will be structured. This allows the development of protocols that support competition by enabling installation of equipment on many different aircraft types.

“Airbus IPS product policy is not defined yet, and will be – as for any other data link introduction in the past – also conditioned to the airline business cases at fleet level,” says Luc Emberger, data link expert - Communications R&T projects leader at Airbus.

“Once standardization activities will be completed and resulting standards endorsed by the main suppliers and service providers, IPS to support aeronautical safety services on board Airbus aircraft will be investigated in regards of our industrial roadmap,” he said. “This is a long process as is any new aeronautical activity which implies international standardization bodies.”

Emberger says Airbus sees its first priority as establishing a standardization and regulatory roadmap and making progress on the key topics like cybersecurity aspects, integration of IPS in the current avionics architectures, and the definition of relevant “aeronautical constraints, including software qualification, verification, and validation means,” he says. AVS