As new airspace operational mandates loom, and digital technology advances functionality, airlines are making critical decisions with respect to avionics upgrades. Increasingly, that means uploading more capable software.

“Software retrofits are preferred in lieu of wholesale line-replaceable unit (LRU) hardware change-outs, so the OEMs are certifying software product improvements for existing LRUs,” states Mitch Klink, vice chairman of the Avionics Maintenance Conference for Arinc industry activities. “But given the current economic environment at the airlines, any desired software upgrades from the OEMs would have to be justified through strict return on investment (ROI) calculations.”

That being the case, Klink points out that software functionality enhancements pertaining to the NextGen Air Traffic Modernization program are now considered “the biggest bang for the buck.” But the highest priority, he says, are communication and navigation, and flight management systems (FMS) upgrades, since they contribute to fuel-saving, aircraft routing efficiencies.

Mario Araujo, vice president engineering at TAP Maintenance and Engineering in Lisbon, notes that other evolving air traffic management (ATM) systems implemented worldwide, such as the Single European Sky ATM Research (Sesar) program, and Japan's Collaborative Actions for Renovation of Air Traffic Systems (Carats), will mandate new avionics capabilities.

“That will be costly, along with the challenges to getting the parts in a timely manner, and to incorporate the changes in the aircraft without jeopardizing the operation. All the maintenance and operations manuals and certification paperwork will have to be ready in time. That will require considerable synchronization planning across several domains—along with a lubricated logistics scheme.”

Araujo also cited controller-pilot data link communications (CPDLC) requirements for European Union airspace, which mandated CPDLC on new aircraft out of the factory from Jan. 1, 2011, and retrofits by Feb. 15, 2015. The mandate, known as LINK 2000+ impacts all aircraft operating under instrument flight rules (IFR) above Flight Level 285. “This is a major modification in which we are investing around $12 million to bring our European fleet of around 40 short-haul Airbus planes into compliance,” he says.

Compliance will involve a data link utilizing VHF radio that will enable transmission of commands via a textual system, according to Craig Peterson, director of avionics and flight-control systems for Rockwell Collins. The software upgrades required to enable this, he explains, primarily involve the on-board radios and routers, as well as the control display unit that encompasses the keyboards and other interfaces.

“It's safe to assume that anything that has something to do with with the aircraft's communication infrastructure will have to be updated to meet the requirements,” Peterson remarks. “Given the time frame and complexity of the systems involved, LINK 2000+ is probably one of the more invasive mandates we have seen.”

He points out that, depending on the aircraft, a number of issues will be involved on the retrofit side.

“Operators will have to determine the capacity of the LRUs to accept the required, more-powerful software,” Peterson says. “That will depend upon the age of the aircraft. The biggest challenge in doing this will be the certification and approval process that airlines flying older aircraft will have to go through to install updated equipment—hardware and software,” he adds.

Another potentially costly mandate for EU airspace is TCAS 7.1, which must be applied to any aircraft exceeding 5,700 kg (12,566 lb.) maximum certified takeoff weight, or authorized to carry more than 19 passengers. Here, forward fit was effective March 1, 2012, with the retrofit deadline Dec. 1, 2015. According to TAP's Araujo, the TCAS upgrade resolves some safety issues identified in the warning logic within the current TCAS 7.0.

“In more modern aircraft this is going to mean just a software change, with a typical cost of $25,000, and less than two man-hours to achieve, including testing,” he explains. “But older legacy aircraft might require change out of the main TCAS computer, bringing the total cost in the vicinity of $120,000, and five man-hours—if no further changes to the TCAS system installation are required.”

Airlines should consider TCAS 7.1 retrofits as a coming requirement—globally, according to Klink. “I expect the regulatory authorities in other regions of the world to follow the EASA mandate, as currently issued for European airspace,” he says. “This upgrade represents a four-fold increase in safety compared to the previous version for improving the monitoring of pilot responses to a Resolution Advisory (RA), and re-issuing a modified reversal RA command if the aircraft is not responding properly to the original command.”

In 2013, Honeywell will introduce a TCAS 7.1 software upgrade with a certified data loader for on-wing installation, says Dave Luken, Honeywell's vice president of sales-air transport and regional. The on-wing upgrade capability, he said, is generally applicable to most aircraft built within the past 15 years.

Regulatory mandates do not always drive avionics software upgrade programs. Two years ago, Southwest Airlines initiated its “Southwest Aircraft Self-Monitoring Project” for its Boeing 737-700/-800 fleet. The project involves a software upgrade that is focused on the health management and reporting functionality of the aircraft condition monitoring system (ACMS), according to Kirk Majors, the airline's avionics software engineer.

“The goal is to improve or enhance data-gathering and management concerning the aircraft's health status in order to identify any potential problems before the airplane reaches the gate,” he explains. “This includes the digital flight data acquisition system, the communications management unit, the bleed air systems and fuel burn.”

Majors reports that the airline does not anticipate a need for any significant wiring changes or shielding requirements. “In terms of hardware, the components we have on our next generation 737s already have the reporting capacity and capability we need to accommodate the software upgrade.”

The project, expected to begin testing in November 2012—and implementation in 2013—will be coordinated with the FAA, the systems OEMs and Boeing to ensure compliance and compatibility with all of the aircraft systems. Certification would be conducted under a Boeing service bulletin, or a supplemental type certificate.

One of the major tasks, says Majors, is to determine which departments at the airline will have access to the data coming off the aircraft. “We have to decide which part of the data applies to what specific department, and then we have to find a way to get the data to that department,” he explains. “Once retrofitted with the new software, the airplane will generate a tremendous amount of data, so arrangements will have to be made to store the data and establish security measures.”

Ken Snodgrass, vice president of marketing and product management-integrated cockpits for Honeywell, points out that, once the data is on the ground, the problem is how the user deciphers and sorts the data in order to come up with a meaningful answer. “There are a lot of algorithms involved. The airlines want to collect more data, so storage on the aircraft is becoming an issue. We are solving this, either with a new communications box on older aircraft, or integrating (more storage-capable) software into existing hardware on newer airplanes.”

US Airways is in the process of upgrading the FMS installed on its Airbus A320s to make the aircraft compatible with the more tailored departures and approaches available under required navigation performance (RNP) specs. The upgrade, which began two years ago, involves 80 of the carrier's 240 A320s, with 40 done to date, says Ken Przeslica, the airline's manager for avionics engineering.

Przeslica explains that an extensive amount of hardware modifications are involved, including the installation of a multi-mode receiver (MMR) unit combining an ILS and a GPS receiver. This is done during a scheduled C check, given the extensive wiring changes and access to wiring bundles involved.

In addition, a GPS antenna must be mounted and MMR activation software loaded into the FMS.

“The complete modification requires about 400 man-hours, including the time for the software download,” Przeslica notes. “For the A320's FMS, Thales—the OEM—made the memory partitions more capable of accepting future upgrades in order to support increasing database sizes within the FMS units. With RNP, this will be extremely important because additional way points will need to be incorporated.”

Przeslica notes that RNP will permit substantial fuel savings, and give the entire A320 fleet a similar configuration at US Airways. “We wanted to bring every aircraft up to RNP capability, so the crews could be trained for that on any member of the A320 family we fly.”

By December 2020, the FAA's NextGen ATM is slated to be up and running, and aircraft operating in the U.S. airspace will have to be equipped with an ADS-B Out transponder. “We've decided to be an early adopter of this, and are now working to bring our A330 fleet to that standard. That will involve a software upgrade, on-wing, because the hardware was developed to a level that accepts the software for the ADS-B Out configuration.”

US Airways, he reports, has partnered with Phoenix-based ACSS to perform the upgrade. “They built the hardware and developed the software. We are working with them to get through the certification process.”