Airlines Turn To ACARS Over IP To Keep Data Moving

Modern commercial aircraft are in effect flying databases, generating ever more detailed data on aircraft and engine performance.

Using Aircraft Communications Addressing and Reporting System (ACARS) technology, airliners have been transmitting aircraft health and maintenance information since the mid-1980s, with the aim of giving maintenance personnel a heads up on what work is needed so planes and helicopters can be turned around more quickly.

The newest aircraft produce as much as 75% more ACARS data than previous generation aircraft, according to Collins Aerospace. That means the way in which ACARS data has been traditionally transmitted—using VHF, HF, and narrowband safety services satellite communications networks (SATCOM)—is no longer sufficient.

The solution that Collins, other aviation technology providers, and airlines are gravitating to is ACARS over internet protocol (IP), which utilizes a commercially or publicly available broadband alternative to transmit much of the data.

“ACARS over IP is one of the key technologies that is driving the ability to get large amounts of data and messaging off the aircraft using modern communications methods,” Philippe Rouquiere, Collins’ product marketing lead for enablement products, told Avionics International.

Not all data would be transmitted via an IP datalink. Dispatch-critical or Air Traffic Service (ATS) ACARS data would still be sent over VHF and narrow band safety services SATCOM. But ACARS data that is not safety critical would be moved to IP transmission.

“There will be continued stress on VHF ACARS capacity without any change,” Rouquiere said.“With the newest generation of aircraft having the capability to generate ACARS data at a rate that is multiples of earlier generation aircraft, these aircraft and other newer generation aircraft collectively are demanding more and more ACARS capacity to support the growing volume of traffic.”

“One particular value of ACARS over IP is the ability to offload the growing volume of aircraft operations ACARS information from VHF, HF and narrow band safety services SATCOM to a broadband connectivity, such as cellular or IP capable SATCOM,” Rouquiere added. “These airline operations ACARS messages do not need the network performance requirements as safety critical ATS ACARS data. Therefore, a commercially or publicly available broadband alternative connectivity is suitable.”

To be equipped for ACARS over IP, according to Rouquiere, an aircraft needs an Aircraft Interface Device (AID) connected to the aircraft’s ACARS management unit.

It also needs an AID that is capable of encapsulating ACARS 618 messages into an IP format ready for transmission, and doing the reverse for received messages. A high degree of security, such as a Virtual Private Network (VPN), is also necessary, he said.

Finally, a ground system is needed to convert the ACARS over IP messages sent from the aircraft into a format to be forwarded to relevant end users, such as an airline or an aircraft manufacturer.

“Newly delivered aircraft have an AID fitted as basic, but there is also a retrofit option,” Rouquiere said. “For example, the ground Flight Operations and Maintenance Exchanger (FOMAX) AID [produced by Collins in conjunction with Airbus] that is delivered on all new A320 and A330 aircraft includes integration with the air traffic service unit (ATSU), as well as optional broadband cellular and satellite capabilities to enable ACARS over IP. The FOMAX AID is connected to a ground-based application that receives and processes ACARS over IP-based messages that are fully interoperable with the legacy ACARS network.”

Other aircraft, such as the Airbus A350, have similar linefit capabilities with many more having retrofit options, Rouquiere said. This has increased the adoption of ACARS over IP dramatically over the last couple of years and has provided the airline industry with considerable opportunities to use this data, especially if delivered in real time and en-route, for driving efficiencies throughout the airline operation, he said.

Since late 2021, Kuwait Airways has been using Collins’ Ground FOMAX system, enabling two of the carrier’s Airbus A330neos “to uplink and downlink non-critical and non-air traffic control messages via IP link,” according to Collins.

Ground FOMAX utilizes a VPN-secured IP connection between the aircraft and the ground. Collins said the equipped Kuwait Airways aircraft are able to send nearly 80% of their ACARS data through an IP connection.

ACARS is widely deployed in the airline industry.

“Hundreds of applications that utilize ACARS data exist today to serve not only airline operations and air traffic services, but also to support in-flight passenger services,” Rouquiere said. “In addition, aircraft increasingly send a wide range of performance data from aircraft systems. The growth of aircraft operations data caused the next jump in the need for capacity.

Activating ACARS over IP puts the airline in the right position strategically to easily adopt developing applications to enhance the aircraft maintenance and operations, combating costly delays and cancellations, and to improve real-time flight data accessibility and seamless data sharing within the aviation ecosystem.”

Cebu Pacific, A Philippines-based low-cost carrier, utilizes SITA FOR AIRCRAFT’s ACARS over IP solution on its Airbus fleet. In a video presentation detailing why the airline chose SITA’s product, Mark Angelo Banting, who oversees aircraft communications and operations support at Cebu, said the carrier was seeking “a comprehensive new service plan that enabled us to transfer data through both conventional and new data channels. But at the same time, we also wanted to save on operating costs and increase our data transfer capability.”

Using ACARS over IP, “we were able to transfer [aircraft and engine health] reports on the ground much faster and more cost-effectively than with conventional datalink,” Banting added. “Secondly, a number of the domestic airports we fly to are surrounded by high terrain and, while they aren't able to have VHF ground stations due to infrastructure limitations, they do have 3G connectivity. ACARS over IP using terrestrial cellular networks enables us to share our [data] instead of having to wait until a VHF ground station is in reach.”

He said Cebu has transferred 30% of its ACARS data traffic to SITA’s ACARS over IP solution.

ACARS over IP can help carriers meet their cost-reduction and sustainability goals, according to Rouquiere.

“Amidst the escalating pressure on airlines to achieve higher profitability and sustainability, all while enhancing passenger satisfaction, the significance of connectivity within the aviation ecosystem has grown enormously,” he explained. “It has evolved into seeking ways to improve real-time flight data accessibility and seamless data sharing within the aviation ecosystem. This information will facilitate better decision-making processes, enabling the airline to proactively identify potential issues, mitigate risks and optimize operational efficiency.”

Rouquiere added that ACARS over IP enables improved data collection, integration of data with maintenance applications, reduced paperwork, increased situational awareness, and real-time flight performance tracking.

ACARS over IP “facilitates collective problem-solving and the establishment of industry-wide best practices, ultimately benefiting both the airline and the entire aviation ecosystem,” he explained. “The potential operational savings of all of these elements put together is hard to quantify, but is undoubtedly significant.”