ACARS: Timeless tech for the connected aircraft age

ACARS: Timeless tech for the connected aircraft age Since 1978, ACARS the Aircraft Communications Addressing and Reporting System has been an invaluable primary aircraft data messaging system for airlines, supporting their safe, secure and efficient operation, while meeting aviation regulations. In this white paper we explore how ACARS is evolving in the connected aircraft age and why it will remain the aviation industry s trusted and reliable network in the years to come. Contributors: Paul Gibson: SITAONAIR Portfolio Director, AIRCOM Euan Mitchell: SITAONAIR Datalink Product Manager

The evolution of ACARS When ACARS technology first came into use in 1978, it relied exclusively on Very High Frequency (VHF) radio channels. On its first day of operation, around 4,000 messages were sent across the ACARS network, with adoption steadily increasing until it became widespread from the 1980s. Today, SITAONAIR operates over 1,700 radios around the world, supporting more than 16,000 aircraft in their daily operations. The intervening years have seen a sharp increase in the demand for air travel and the steady addition of alternative means of transmitting aircraft data. These new technologies have enhanced the geographical coverage of ACARS and developed its capability for automatic and manual messaging. Paul Gibson, Portfolio Director, AIRCOM at SITAONAIR, explains: Today, ACARS continues to evolve from its VHF origins, with satellite services, higher speed VHF Digital Link (VDL) introduced at various stages, to deal with the steady rise in air traffic. As various forms of Internet Protocol (IP) links become available to aircraft, we have been taking strides to ensure ACARS evolves to further enable message transmission over IP. This increasing demand for air travel, and ongoing technological advances, mean that ACARS has never been more valuable to the modern air transport industry, delivering the safest, most reliable technology for pilot-to-atc communications.

What is ACARS? ACARS (Aircraft Communication Reporting and Addressing System) is a datalink system used for the transmission of messages between the pilot and ground stations. These messages can be sent using a variety of communication methods, including VHF and HF (High Frequency) radio channels, or via satellite. The term, ACARS, refers to the complete system that enables ground-to-air aircraft data message communications. This system includes the service provider as well as the equipment in the air and on the ground. Typically, ACARS messages conform to one of three main types: Air Traffic Control (ATC), Aeronautical Operational Control (AOC) or Airline Administrative Control (AAC). ATC messages include aircraft requests for departure or oceanic clearances, as well as any other instructions from ATC to the aircraft. For AOC purposes, the majority of ACARS data is used for operational and administrative purposes and is integral to a wide range of airline process and information exchanges. These include communications on connecting gates, updated arrival times, aircraft weight and balance, and aircraft and engine health monitoring.

The value of ACARS to the industry Since the late 1970s, ACARS technology has become ingrained in global airline flight operations underlined by the fact that its capabilities are linefit as standard across airline fleets around the world. Today ACARS is part of the fabric of most airlines, many of whom build their entire operational processes around the system. ACARS ubiquity across the industry stems from the safety, cost and operational benefits that the technology can bring. Through ACARS, data ranging from maintenance and aircraft health information, through to the granting of departure clearance and instructions on changing flight levels, can be sent. The only single global service for aviation ops communications In the decades since its inception, SITA, now SITAONAIR, engineers have continued to fully integrate technologies emerging onto the aircraft data messaging market within the central ACARS system. These technologies have included the addition of satellite networks and, more recently, the exploration of culture-shifting communication links such as Internet Protocol (IP), or ACARS over IP, including the use of ground-based terrestrial cellular networks for data exchanges while the aircraft is on the ground. For airlines, the benefits are huge, as ACARS maintains its traditional reliability and efficiency, while embracing continued technological advancement in the connected aviation environment. Supporting ATC communications, navigation and surveillance With the IATA (International Air Transport Association) projecting that a staggering 7.2 billion passengers are set to take flight in 2035, SITAONAIR s collaborative action to incorporate emerging technology and innovation has been invaluable. According to a recent Inmarsat study, conducted by aviation consultant Helios, satellite communication alone saved the airline industry $3 billion between 2001 and 2016. When expanded to consider the operational efficiencies from the use of VHF and VDL during the aircraft turnaround process and gate-to-gate, the operational savings would be considerably higher. As IP networks start to converge around aircraft communications, it is important to identify that some networks are unlikely to be suitable for ATC communications, meaning that a highly integrated approach is required to make datalink services work seamlessly across an increasing number and variety of networks. As Paul Gibson explains: SITAONAIR s position is that, while feasible in principle, not all flavors of communications channel are equal. Traditional ACARS and ACARS over IP both have an important role to play in today s ground-to-air connectivity landscape. Certain critical data is unlikely ever to be sent over some forms of IP. In the rare case that it is, it will almost certainly be on a multi-link basis, in that there is always the ability to fall back to another link.

A system that just works In an environment where critical data is transmitted across multiple communication channels, it is vital that the system inspires industry-wide confidence. There needs to be certainty that data is delivered in a consistent and seamless manner across all platforms. As Euan Mitchell, Datalink Product Manager at SITAONAIR, elaborates: Given the absolute importance of this to both safety and efficient airline operations, most airlines would not be willing to accept a reality where they would rely on a single link capability without automatic failover to an alternative. the industry s operations. Given today s crowded skies and runways, it is ACARS ability to integrate modern technology reliably and across all regions that has maintained its central role. As one of the major ACARS service providers, SITAONAIR continues to play a leading role in supporting airline value, safety and aviation regulations. Far from resting on ACARS position as the ubiquitous ground-to-air datalink system, SITAONAIR is central in ACARS evolution in the connected aircraft age. It is this ability to adapt and evolve that means more than 220 airlines now rely on SITAONAIR ACARS technology. What s more, from an airline perspective, Euan continues, any digital data system for the transmission of messages between ground and air simply has to work, as dispatching an aircraft using manual processes is immensely challenging. It is our role as a datalink service provider to ensure this critical communications system functions effectively, reducing airline workload. This fundamental requirement means that airlines ultimately require faultless reliability from the technology, which is precisely what makes ACARS and SITAONAIR so successful and integral to SITAONAIR s role in the evolution of ACARS SITAONAIR does more than simply implement ACARS protocol; it remains a core service provider for airlines around the world. Central to SITAONAIR s position is its ability to integrate multiple networks, both proprietary and third party. In addition, SITAONAIR provides one of the largest secure private ground networks anywhere in the world, with the capability to link ATC, airlines, airports and OEMs. Combined with 24/7 support and dedicated airline customer support representatives, SITAONAIR provides industrialized levels of service, ensuring high availability, resilience and redundancy. SITAONAIR is also independent and agnostic, separate from OEMs and specific satellite network providers. These capabilities ensure that SITAONAIR s value as a service provider is to support airlines in managing the transition required to reap the benefits of new technology, without causing any major disruption. Ultimately, SITAONAIR is managing the complexity of ACARS, so airlines don t have to.

ACARS in the connected aircraft age With the IATA expecting airlines to have operated 38.4 million flights in 2017 (up 4.9% on 2016), and with SITAONAIR estimating around 10 million ACARS messages exchanged daily, ACARS is still the primary means of communication to ATC and airline operations. Indeed, ACARS remains the backbone of aviation communications, empowering airlines and ANSPs to deliver safe, consistent and reliable pilot-to-atc communications. Paul explains: ACARS has proven its ability to work alongside more modern methods of groundto-air communication, avoiding the traps that have snared alternatives by working seamlessly across all aircraft types and all regions. There is no one-size-fits-all approach when it comes to effective ground-to-air communication. Each airline needs to consider its own requirements and adopt the most suitable ACARS innovations and methods. For an airline operating in a particularly busy airspace or airport, or those operating in regions where there is only very limited VHF coverage, a mixture of approaches is often the most appropriate. SITAONAIR and Teledyne cockpit comms cellular service SITAONAIR and Teledyne have announced a partnership to deliver the aviation industry s first ever airline-integrated ACARS datalink terrestrial cellular service, illustrating the role the technology continues to play in the modern connectivity era. The partnership marks an important evolution in airline and aircraft communications. Building on the datalink services chiefly provided by using VHF/VDL radio frequencies, the agreement enables SITAONAIR to integrate terrestrial cellular services into its core datalink network. The result is that airlines gain the flexibility of another transmission channel for aircraft communications. By enabling the datalink service over 3G/4G, the airline community can benefit from increased capacity for message transmission. At the same time, the partnership helps to relieve traditional datalink networks in congested airports, by freeing up important capacity for essential ATC communications while also supplementing traditional VHF datalink ground coverage in sparse areas. This is a prime example of the role ACARS still plays, adapting to and complementing new innovations in airline and aircraft communications. Inmarsat SwiftBroadband-Safety Inmarsat SwiftBroadband-Safety (SB-S) is a next-generation flight deck communications platform that enlists ACARS technology to offer a global, secure and high speed IP connectivity for the cockpit. It delivers faster communications, alongside a dedicated IP connection to the cockpit, paving the way for both airline operational applications and future new generation safety applications.sb-s is well positioned to be the primary operational cockpit link with the aircraft, with VHF networks becoming a required back-up. As a sign of the technology s success, and ACARS crucial role within that, several airlines, including United Airlines, are to participate in a technology evaluation of SB-S. The technology is being assessed on four Boeing 767 aircraft as part of the airline s commitment to operational, safety and service improvements. SB-S will deliver flexible communications with realtime flight information that can serve to enhance both airline security and safety. It supports this through continual positional awareness flight tracking, and the dedicated IP connection to the cockpit, which supports flight data streaming and real-time EFB applications, including weather awareness. SB-S, as a future standard for aircraft communication, illustrates the ongoing evolution of ACARS and the key role it continues to play in innovative and market leading ground-to-air communications technology. Backbone of efficient airline operations

New gen European ATC-airline communications network In a live demonstration of the continued evolution of air-to-ground communication capabilities, Europe s primary ATC-airline communications network has been upgraded by SITAONAIR, delivering Europe s first Multi-Frequency (MF) Very High Frequency Digital Link mode 2 (VDLm2) infrastructure. VDLm2 provides the capacity required to support both ACARS and Aeronautical Telecommunication Network (ATN) messaging. The MF-VDLm2 infrastructure has been delivered on behalf of subscribing Air Navigation Service Providers (ANSPs) and will serve 85% of all Europe-based ATC-airline communications. It is supporting the use of CPDLC (Controller Pilot Data Link Communications), as mandated by the European Commission. The MF-VDLm2 infrastructure has been deployed to resolve the ATC-airline communications frequency capacity issues that have impacted the single-frequency VDLm2 network since 2015. Prior to using CPDLC, airlines within European airspace used voice messaging over VHF to communicate with ATC. Under CPDLC, however, communications rely on the automated messaging capabilities of digital link. This improves the accuracy, efficiency and consistency of routine ATC procedures. The MF-VDLm2 infrastructure under deployment by SITAONAIR offers more capacity throughout Europe, and will support the performances required by the CPDLC mandate. The implementation, together with the ATN routing protocols, allows a wider range of information to be transmitted and a much faster connection. The nature of these evolving air-to-ground communication technologies again demonstrates ACARS technological adaptability in managing the growth of air and communications traffic. Prague s VHF/VDL ATC communications gateway VHF, VDL and legacy networks will continue to work in parallel with IP networks, with the two technologies complementing one another. While IP certainly brings great opportunity, it also needs to be grounded in clear and valuegenerating use cases, fully considering the impact of safety and the levels of aircraft integration required. For many, the value and safety assurances delivered by existing ACARS media remains the best, most secure, and most flexible option. Indeed, airline operators, air navigation service providers (ANSPs) and airports continue to rely on traditional ACARS networks and SITAONAIR as their trusted partner for ground-to-air messaging. As a case in point, the Czech Republic s ANSP, ANS CR, has enlisted SITAONAIR to deliver a communication gateway to Prague Airport through its ACARS network, with the ambition to roll it out to other Czech airports in the future. SITAONAIR s communication gateway will enable the Air Navigation Service of the Czech Republic (ANS CR) to support the sending of terminal information (D-ATIS) to arriving aircraft and departure clearances (DCL) to departing aircraft. By replacing routine messages carried over congested voice frequencies with standardized digital messages, these ATC datalink applications are minimizing the risk of misunderstandings and confusion. Examples like Prague illustrate SITAONAIR s continued investment into VHF and VDL networks, and strong belief that these, alongside other networks, will continue to work in parallel with newer generation technologies.

Expansion of VHF The longevity of VHF and VDL is underlined by progress in developing parts of the world, where the development of VHF networks remains the primary focus as air traffic and data volumes increase. In 2015, SITAONAIR completed the deployment of a comprehensive VHF and VDL datalink network across more than 50 sites in Brazil. The expanded network delivered full coverage of Brazilian airspace and allowed airspace users to access both the Departure Clearance (DCL) and Digital- Automatic Terminal Information Service (D-ATIS) datalink services that were deployed at 23 control towers across Brazil. The project in Brazil posed particular challenges, including the difficulty of transporting, installing and operating the hardware in environments as harsh as the Amazon jungle. Its completion provided the country with advanced datalink communications, while paving the way for future ATC datalink communication services over the ACARS network. While ACARS is undoubtedly still evolving beyond its VHF origins in some respects, VHF channels will remain essential for ATC communication, particularly in more remote corners of the world. SITAONAIR and the future of ACARS ACARS remains heavily integrated into the ground systems of nearly all airlines for a reason. SITAONAIR s position as datalink service provider ensures the seamless addition of new airline technology into the airline ecosystem giving airlines the confidence that when called upon, the technology simply works. SITAONAIR champions the evolution of nextgeneration connected aircraft and continues to pioneer and innovate. Its vital, aviation authoritycompliant ACARS ecosystem ensures that it remains an industry staple empowering airlines and ANSPs to deliver safe, consistent and reliable ground-to-air communications that are fundamental to their successful operations. Traditional ACARS technologies have been providing reliable ground-to-air communication for more than 30 years. While VHF will continue to have its place, both for reliable and efficient ATC communication, and as a back-up, SITAONAIR s implementation of advances such as ACARS over IP secures its position as the fundamental means of aircraft addressing and reporting. Ultimately, ACARS remains the most reliable, efficient and cost-effective ground-to-air messaging system there is. It has played a fundamental role in the industry for decades, meaning that there are now a countless number of systems relying on it and huge volumes of integrated data coming to and from aircraft via ACARS messaging. Its ubiquity across the industry, and ability to evolve with the connected aircraft era, ensures that ACARS will long retain its position as the foremost tool for aircraft addressing and reporting, and SITAONAIR as its core service provider. WHY SITAONAIR? SITAONAIR is the air travel industry s trusted connected aircraft service expert. With its unrivalled industrybacked heritage, SITAONAIR empowers 400+ airlines and 16,000+ aircraft to navigate the complexity of connectivity and unlock connected aircraft value. We work in partnership with the air travel community, helping support its digital transformation, to unlock the true value of data, grow ancillary revenues, and enhance the passenger experience, operational efficiency and airline safety. Our co-created solutions for passengers, cockpit and cabin crew, and aircraft data management, equip the industry to address the challenges and valuegenerating opportunities it presents. SITAONAIR around the world Atlanta - Brussels - Dubai - Geneva - London - Montreal - Paris - Rio de Janeiro - Singapore Want to find out more? Email us at worldwide@sitaonair.aero or visit sitaonair.aero