An industry working group’s recommendation to delay the November 2016 deadline for implementing aircraft tracking using current technology is rooted in concerns that rushing the effort could lead to unsafe scenarios, and an extra two years are needed to mitigate that risk.
Members of the Normal Aircraft Tracking Implementation Initiative (Natii) reached their conclusions with the help of a series of tabletop exercises held over the summer, according to a report delivered to the International Civil Aviation Organization (ICAO) in September. The exercises showed that unexpected circumstances—such as the failure of a primary system used for tracking—could raise risk as flight crews scramble to ensure their aircraft are being tracked. They also made clear that procedures such as how to handle missed reports when aircraft were transitioning between flight information regions (FIR) must be hammered out as part of a prudent approach to implementing flight tracking.
The push to track all flights, elevated after the June 2009 crash of Air France Flight 447 in the Atlantic Ocean, gained unprecedented momentum after the disappearance of Malaysia Airlines Flight 370 in March 2014. Two months after the Boeing 777 was lost, the international civil aviation community, led by ICAO, established the Global Aeronautical Distress and Safety System (GADSS) concept of operations. The effort’s focus includes implementing near-term standards that rely on existing technology and establishing more robust, longer-term standards. The plans will be laid out in new ICAO Standards and Recommended Practices (SARP), which, while not mandatory, are de facto requirements for state-level regulators to include in their rules.
Natii was formed in February 2015 to help develop real-world guidance for tracking. “The initiative identified existing practices used by some operators to determine the location of their aircraft when operating in oceanic areas, as well as challenges facing the practical implementation of Normal Aircraft Tracking (NAT),” the report explains.
Most of the challenges came to light during six “what-if” exercises conducted during a two-day meeting in June. Each exercise picked a route and a scenario in which an aircraft and an air navigation service provider (ANSP), where applicable, was required to follow proposed tracking standards. Chief among them: providing and receiving so-called 4D/15 data—latitude, longitude, altitude, and time. Operators receiving the information from aircraft, regardless of an ANSP’s coverage capabilities, are defined as 4D/15 Tracking. An ANSP receiving the information directly from aircraft is 4D/15 Service. Both are seen as necessary for a complete, redundant tracking initiative.
The exercises reinforced that technology exists to accomplish the near-term tracking initiatives. But they also highlighted the ramifications of possible system failures and inadequate guidance.
“Most significantly, the Natii identified scenarios where the prescriptive nature of the proposed SARPs imposed an unrealistic operational burden across industry stakeholders,” the report states. “The proposed SARPs have the potential to result in a number of unintended consequences to operations, especially when elements required for Normal Aircraft Tracking become unavailable.”
In one scenario, a 777 flying from Sydney to Tokyo’s Narita International Airport lost its Automatic Dependent Surveillance-Contract (ADS-C) capabilities. The flight continued, because the ANSPs along the route supported high-frequency (HF) communications. But the group found that relying on manual means, such as the HF capabilities, to meet the 4D/15 reporting standard created significant additional workload “and had a negative impact on the overall safety of the operation,” the report notes. Manual reporting also introduces uncertainty. “In other words, the manual report could indicate that the aircraft was in one location when it actually was in a different place.”
Natii suggests that fulfilling the Normal Aircraft Tracking requirements and recommendations should be done with automated systems only.
In another scenario, an Airbus A340 with only a data link was flying from Sydney to Santiago, Chile. The limited equipage meant the operator had to provide tracking along the route. The scenario had the aircraft miss a report when it was near an FIR. “By the time the operator had performed its established procedures (i.e., attempting to reestablish a 4D position and/or establishing communications) the aircraft had crossed the FIR boundary,” the report says. “Although prevalent in all scenarios, this scenario highlighted the need for operators and ANSPs to have up-to-date operational contact details.”
This scenario led to a recommendation for a central database, “preferably hosted by ICAO,” of contact details for airline operations control centers and ANSPs.
In another scenario, a Bombardier Q400 was flying between Cairns, Australia, and Port Moresby, Papua New Guinea, a 90-min. flight over the Coral Sea. The route selected has a 30-min. 4D/15 Service gap, meaning the aircraft and operator needed 4D/15 Tracking capability for dispatch.
The aircraft was equipped with a portable tracking device to enable the flight crew to meet the proposed tracking requirements. The scenario tested the device’s failure combined with the operator’s inability to contact its aircraft. In the scenario, the aircraft lost contact while in the service gap but was back on radar before the operator made contact with the ANSP.
“This scenario highlighted the need for operators to develop procedures to assess the aircraft tracking system’s serviceability,” the report notes.
It also raises the question of whether such short gaps should trigger the tracking mandate. Participants “also questioned whether 4D/15 Tracking was necessary for this type of operation (i.e., short 4D/15 Service gaps),” the report continues, adding that the exercise “identified the need for complementary ICAO provisions to address the scenario when 4D/15 Tracking capability does not exist for short segments where 4D/15 Tracking would be required.”
Another topic covered by the exercise was data retention. The working group “took into consideration [air traffic service] unit recording requirements and concluded that, unless there was an accident, there was no need to retain tracking data after the aircraft had landed safely under normal tracking conditions,” the report says. Accordingly, Natii recommends that data retention only be used “for the purpose of assisting [search and rescue] in determining the last known position of the aircraft.”
The report makes 13 recommendations, focusing on the proposed SARPs and related guidance. It also calls for developing “complementary risk-based variations to the prescriptive requirements” that would maintain safety while ensuring compliance with the SARPs.
“Aware of the ICAO processes, the Natii determined that an implementation period to the proposed SARPs should be established that would permit the necessary time for all of the aforementioned tasks to be completed. This could be accomplished by extending the proposed applicability date to November 2018.”
In addition to the two-day tabletop exercise meeting, Natii’s work included regular discussions in April-September 2015. Among the general conclusions reached during the working group meetings: Industry overestimates the costs of available tracking services.
“Several vendors noted that operators in general appear to have a perception that the cost of tracking is high,” the report says. “They presented some system solutions that were relatively inexpensive. That disconnect between the perceived cost and the actual cost meant that many operators were not considering all of the available tracking system options.”