E-GADSS! Flight Tracking Developments By Charlotte Daniels

E-GADSS! Flight Tracking Developments By Charlotte Daniels

ICAO and regulators are introducing location reports and tracking practices that adhere to the GADSS tracking initiative. Aerospace Tech Review is exploring global flight tracking developments and the implications for future operations.

To prevent or minimise air accidents, search and rescue organisations must locate aircraft at the earliest possible opportunity. What is learnt from historical accidents, can at the very least go towards future mitigation.

Investigations into Air France 447 and Malaysia Airlines MH370 led to an industry re-assessment of aircraft tracking and reporting capabilities. Both aircraft descended into oceanic regions (the Atlantic and Indian Ocean respectively). MH370 remains unrecovered.

The events highlighted the difficulty tracking and tracing in remote regions, and an onus on location reporting. Spearheaded by ICAO, the Global Aeronautical Distress and Safety System (GADSS) tracking initiative was developed, and has been in process since 2014.

While the traditional method of location reporting relied on radar and high frequency (HF radio), these were methods that were often not covered in remote or oceanic areas. Today, satellite coverage means that aircraft can be tracked worldwide, whether oceanic, polar or remote land-based areas. Space-based ADS-B or Satellite-based tracking devices can meet the Aircraft Tracking requirement. However a blend of terrestrial ADS-B and ACARS and other messaging could also meet the recommendation.

To utilise space ADS-B, aircraft require an ABS-B Out or Mode S transponder. “These are installed on most current aircraft,” explains Igor Dimnik, Director, Airline OCC and Crew Application Portfolio at SITAONAIR. “Airlines can therefore track aircraft in remote areas independent of ground-based infrastructure. It means that aircraft not equipped with SATCOM can provide position data anywhere in the world, which will allow airlines to meet mandates without additional equipment.” Dimnik also notes that ADS-B Out avionics are increasingly mandatory in some regions – from January 1, 2020, aircraft operating in FAA airspace must be equipped. ADS-B Out allows aircraft to broadcast identity, location and other information to ATC via the transponder.

ADS-B Out is mandated by EASA from 7th June 2020. “Onus is on the airline to have correct SOPs in place,” advises Paul Gibson, senior product manager at NAVBLUE, an Airbus Company. “They need to ensure transponders are installed but also update SOPs for normal and abnormal operations. It goes beyond the software and hardware.”

The extent to which each operator fulfils the overall GADSS initiative depends on their region of operations, and regulator. GADSS comprises three main functions; ‘Normal’ Aircraft Tracking (AT), Autonomous Distress Tracking (ADT), and Flight Localization & Recovery (PFLR). “Each element has different requirements,” says Ruben Stepin, Director of GADSS & Airline Business Development at SKYTRAC Systems.

Regulatory Support

It is important to recognise that while ICAO is behind the development and promulgation of such initiatives, it is the regulators including the FAA and EASA that roll out mandates to ensure ICAOs standards & recommended practices (SARPs) are implemented. Dimnik of SITAONAIR elaborates that ICAO’s initiative is not the mandate itself. “Only individual civil aviation agencies with regulatory authority over respective flight information regions (FIRs) can enact these,” he determines. “We see slight disparities in responses by civil aviation agencies: many civil aviation regulatory agencies across the globe, including those in China, Europe, Malaysia and Singapore had already issued mandates and published policy guidance documents for operators registered in their respective airspace back in 2018.

“On their side, the world’s most active airline markets such as Europe and US have committed to comply, but with certain specific differences based on the availability of equipment and possibilities to upgrade equipment. As an example, FAA issued in April 2019 an InFO providing air tracking guidance including the recommendation to track the position of aircraft though automated reporting at least every 15 minutes whether in oceanic airspace or over remote continental airspace (when out of ATS tracking areas).”

GADSS Initiative

GADSS consists of several stages. “It comprises the GADSS concept of operations (CONOPS) which arouse from the ICAO GADSS advisory group and outlines overall vision,” says Stepin. The latest version of this, 6.0 was released in 2017.

The three components are recommendations that were developed as the result of working & advisory groups. These place the responsibility of ensuring sufficient tracking capabilities on each individual operator. “These recommendations included Normal Aircraft Tracking (AT) – which came into effect in November 2018,” continues Stepin. “This suggested that operators should be capable of reporting aircraft position every 15 minutes.” This is also referred to as 4D15; the 4 dimensions referring to latitude, longitude, altitude and time. ICAO explains that AT requirements typically apply to long haul aircraft due to the need to be outside of radar coverage over oceanic areas.

To discuss the idea of ‘GADSS compliance’ therefore, we need to differentiate between two types of operations: normal (for AT) and abnormal (for autonomous distress tracking, or ADT).

“ADT comes into force in January 2021,” adds Stepin. “This applies to forward-fit aircraft with the certificate of airworthiness first issued on or after 01 January 2021, and requires aircraft distress events to be able to report location at one minute intervals and which are resilient to failures of the aircraft’s electrical power, navigation and communication systems..

All solutions proposed as distress tracking / ADT systems will need to be available throughout the operators area of operations, according to ICAO. Satellite constellations which cover the globe are can be used for these systems. ADS-B on its own can’t fulfil all requirements for ADT.

“Last, there is a recommendation for Post Flight Localization and Recovery (also referred to as Timely recovery of flight data (TRFD)) that also comes into effect in January 2021, is also for forward-fit aircraft with the ‘application for type certification’ submitted on or after 01 JAN 2021,” summaries Stepin. “It concerns the recovery of Flight Data in a “timely manner’.”

Remote Activation

With ADT, remote activation is required. “The Flight Crew need to be able to manually activate a Distress situation from the cockpit,” explains Stepin. “Manual activation from the ground (from operational control) is not required, but is allowed and recommended, provided the necessary infrastructure on the ground and in the air are met to achieve this.

“Typically Satellite connections are required for this service to work. ELT’s will have to use the Galileo Return Link Service to achieve this,” continues Stepin. “Other Satellite based ADT systems onboard an aircraft could be activated from the ground using the contracted satellite service provision of operator’s choice.”

Operator Considerations

Achieving tracking benchmarks on a global scale requires aligning regulators and operators. But how have SARPs and mandates affected operational procedure in recent years? ICAO has indicated that operators will need processes in place to ensure they are tracking at 15-minute intervals throughout any oceanic area where this is required, additionally the recommendation is that tracking be accomplished throughout the area of operations. Furthermore the operator will need a process to monitor the information received and take appropriate action when necessary – this is true for both AT and ADT.

As discussed, there are two separate requirements relating to ‘normal’ tracking and also tracking for aircraft in distress. There are therefore different requirements pertaining to each, relating to equipment and operational procedures. According to ICAO, normal tracking means the authority will need to determine that the operator has the relevant processes in place. ADT means that additional requirements are needed including the installation of an approved system.

ICAO indicates that typically these systems are expected to be offered by the major manufacturers as standard equipment, however other solutions exist and if an operator wished to use a third party solution they would need to obtain a supplemental type certificate (STC) for the aircraft type. The authority would then need to confirm that this met the requirements of the SARPs related to distress tracking.

“Due to ADT being only a forward-fit requirement, there is more pressure on the OEMs to deliver aircraft with systems in place that comply,” highlights Stepin. “Every OEM will do things differently, and this can be a problem for operators – particularly, those with varying fleet types.

“In addition to this the ground software will need to be able to function and display information correctly in the event of a distress and differentiate those aircraft that are equipped with a system capable of relaying 1-min position reports to the ground and those that are not,” continues Stepin. “If the airline opts to not employ systems that relay 1-min position report information to the ground (to be visualized), such as an ELT, then they would need to have access to the ICAO proposed Distress Tracking Repository (DTR) or a means to “automatically” receive the information from Cospas-Sarsat system (through the Mission Control Centre or the Rescue Coordination Centre).”

The DTR serves as a means to securely store ADT data and make it accessible to authorized users. “This is because ICAO has recommended that the system autonomously transmit information from which a position can be determined “by the operator” at least once every minute,” adds Stepin.

Mark Duell, vice president at FlightAware has observed that for standardisation reasons some airlines voluntarily retrofit aircraft to adhere to ADT. “They’ll schedule it in the next heavy shop visit,” he says. “The idea of an incident without this capability is a strong incentive, in addition to the benefit of fleet commonality to SOPs.”

Hardware & Software

Since the new standards are performance based, there is no specific ‘one size fits all’ solution to regulatory mandates that meet its recommendations. “A safety mandate is often specific to equipment,” explains Gibson of NAVBLUE. “Because the airline is responsible, the way it’s being enforced is via IATA’s IOSA audits.” Adherence is being checked through this audit process.

The solutions that meet 4D15, ADT and TRFD vary. We know that the ADT system will need to be autonomous and meet the requirements laid out in Annex 6 by ICAO, and we know the 15 and one-minute intervals at which operators will likely need to demonstrate they can report location. Each operator will therefore be seeking solutions that complement their operations, and where possible minimise modifications to fleet.

Various hardware & software solutions are explored, to put into context evolving developments to flight tracking.


Software and aviation data provider FlightAware provides flight tracking via a combination of ADS-B, and multilateration ATC feeds including ATC data and ACARS data. Space-based ADS-B is provided by Aireon, and is publicly available on its ‘live flight tracker’ platform. Meanwhile, ACARS is encrypted in transmit and the private property of the operator.

Today, FlightAware Global is tracking 200 airlines’ commercial aircraft and 15,000 business jets and streaming data via its Firehose datafeed. FlightAware’s data is also used for NAVBLUE’s N-Tracking software.

“The extent to which regulators have had to adapt to ICAO’s SARPs varies by region,” says Mark Duell, vice president at FlightAware. “In the US there was already flight following in place, so we’ve not witnessed a huge change to achieve 4D15 in recent years.

“For the rest of the world including Europe and Asia, over recent years we’ve seen a cultural shift,” Duell continues. “It’s gone from crew calling on arrival to a need for constant attention throughout a flight. Rather than taking for granted the ACARS message, the recency of a location update is almost more important than the location itself.” Adapting standard operating procedures (SOPs) to account for alternative procedures and building redundancies into systems to combat IT upgrades and power outages is also increasingly important for location reporting. “Operators need to show that they have the means and alternates to reliably report location in any events,” says Duell.

FlightAware’s GlobalBeacon was developed in part to address AT and 4D15 requirements. The only pre-requisite for hardware is the Mode S transponder. “The software can be utilised by small airlines without established IT resources, because it’s available as a standalone web-based product and therefore does not require complex integration,” explains Duell. 4D15 compliance – even one-minute reporting is therefore relatively inexpensive. Furthermore, the adoption of space ADS-B by well-known operators including Ryanair (an unapologetically low cost carrier) has instilled confidence in this method of global tracking.

For ADT requirements, Duell adds that if operators are using ADS-B to provide location reports every minute than they don’t need to change anything specifically for a distress situation. “If the operator is using Satcom for location reports however than they will need to deploy an alternative method, because legacy pricing renders 1 minute updates too expensive.” Because GADSS ADT is operator centric the carrier has to find an appropriate service, and is responsible for relaying information in distress situations.

As 2021 approaches, Duell observes some divergence between regulatory mandates and ICAO’s GADSS CONOPs. “The overall principle will be adopted, but leading regulators are forecasting 2023 for implementation,” he says. “EASA advises that OEMs feel 2021 is too soon. In part this is because historically, the operator doesn’t have an operational role in search and rescue. Subsequently most don’t have procedures for this. EASA has voiced that location data should therefore go from aircraft straight to the organisation that is doing the search and rescue in this event.”

EASA is the first major regulatory body to come out with guidance. “They are still specifying what operators need to achieve,” adds Duell. “That is, one-minute intervals will still be required for ADT, so that search and rescue can obtain position within six nautical miles. EASA is actually recommending a one second intervals for 200m proximity.” EASA has not incorporated any regulations yet regarding the DTR referenced in CONOPs; it remains to be seen to what extent this is adopted globally.


NAVBLUE is a subsidiary of Airbus, and formally launched its tracking solution ‘N-Tracking’ in August 2019. To date, 25 airlines use this browser-based global aircraft tracking solution.

NAVBLUE relaunched N-Tracking in 2019. The latest version boasts greater coverage due to partnerships with Aireon and FlightAware. NAVBLUE images.
NAVBLUE relaunched N-Tracking in 2019. The latest version boasts greater coverage due to partnerships with Aireon and FlightAware. NAVBLUE images.
To determine where space-based ADS-B is required, NAVBLUE recommends trialling N-tracking without access to this data. The provider then sets alerts when aircraft goes out of coverage.
To determine where space-based ADS-B is required, NAVBLUE recommends trialling N-tracking without access to this data. The provider then sets alerts when aircraft goes out of coverage.

N-Tracking was originally developed by Airbus and utilised ACARS position reports, before NAVBLUE incorporated the software into its portfolio. By reassessing data sources the new version of N-Tracking achieves overall GADSS compliance. Due to new partnerships with FlightAware, AirSense and Aireon, this tracking solution now leverages ADS-B (terrestrial and space-based), ASDE-X, multilateration ATC feeds, FAA and Eurocontrol data and ACARS position data to establish real-time and global position reports. “Via Aireon’s space-based ADS-B, customers can opt to subscribe to 1-minute reports,” says Paul Gibson, senior product manager at NAVBLUE, an Airbus Company. “Oceanic and polar regions can also be covered using ACARS if Iridium or other SATCOM is installed on the aircraft, but this can be costly. Moreover, narrowbody aircraft don’t tend to be satcom/ACARS equipped. A subscription based space-based ADS-B service is therefore ideal.”

AT and abnormal tracking requirements are met by N-Tracking: 15- and 1-minute reporting intervals. But what of the autonomous aspect to ADT? “Autonomous distress tracking requires auto activation,” says Gibson. “N-Tracking can autonomously trigger ADT when the aircraft deviates from operational parameters; this can be related to performance i.e. the aircraft deviates from its flight plan, flight level is too high, or it’s descending too fast. ADT can also be time-triggered; for instance if the aircraft doesn’t report location within the 15 minute time frame.” This trigger is facilitated by ACARS and can be configured to send an alert to airline’s operational control centre (OCC).

Determining the right GADSS ‘fit’ for each operator depends on operational network. “It’s difficult to define, say, how well terrestrial ADS-B coverage will perform for their tracking, because it’s hard to match to routes and coverage is constantly changing,” Gibson continues. He describes a recent customer that has started to install Iridium SATCOM on its narrowbody fleet. The aircraft were flying oceanic routes to Hawaii, and the operator had determined SATCOM as the best means to achieve consistent tracking. “After a trial to incorporate N-Tracking into operations the carrier now uses a blend of Iridium and Aireon subscription-based space ADS-B.” This provided a more cost-effective option.

Part of NAVBLUE’s customer trial involves using N-tracking without space ADS-B, and setting alerts that trigger when aircraft goes out of coverage. The customer can therefore determine if space-based coverage is required for certain fleets due to operations.


SKYTRAC Systems offers Flight Following and GADSS compliant software solutions. In addition, SKYTRAC’s parent company ACR Electronics produces ELT-DT’s under the ARTEX brand. SKYTRAC is primarily explored here. SKYTRAC can be installed across all fleet types and provides consistent position data globally. Today, the SKYTRAC hardware systems are installed on over 9000 aircraft and SKYTRAC’s software and server tracks over 14+M position reports monthly.

Stepin advises the various measures he sees operators adopting in order to meet normal AT, ADT and TRFD requirements.AT pertains mostly to software upgrades or changes. While no additional hardware needs to be purchased for new aircraft the operator may choose to enable a space-based ADS-B service.

“While the AT recommendation is for forward- and retro-fit aircraft, we have seen that most aviation authorities have adopted this and mandated it for 19+ PAX/45.5t aircraft flying in secondary surveillance airspace (such as Oceanic airspace),” he explains. “These authorities have also recommended it for 19+ PAX / 27t aircraft, in line with ICAO’s recommendation. This adoption has mainly caused operators to change internal procedures and policies on how aircraft were currently being tracked.

“Most airlines adopted methods for tracking their aircraft using as many possible existing systems onboard the aircraft, such as ACARS, ADS-B, ADS-C and other sources,” continues Stepin. “This data needed to flow into their operational control centre (OCC) software to bring fleet visibility.” Subsequently, most airlines have introduced tracking of their aircraft across the entire fleet, rather than only large 45.5t aircraft.”

Ultimately therefore, most operators can achieve the 4D15 recommendation by ICAO. “Many are opting for space-based ADS-B which provides 1-min position reporting,” adds Stepin. Because SKYTRAC aircraft tracking hardware offers configurable position reporting, operators can elect the frequency and add additional services such as voice & text communication, real-time operations, engine and airframe exceedance notifications.

However, many airlines are approaching SKYTRAC for installed aircraft tracking because the information is private; unlike terrestrial ADS-B which is largely public. ‘Our tracking data is secure, autonomous and maintains service for the entire duration of the flight because of Ni-Mh integral battery back-up,” says Stepin. “Also due to utilising Iridium satellites it is available from pole-to-pole. For ADT, it provides real-time alerts. Last, the operator owns the data so they can choose to make it available to third parties via secure API.”

To be ADT compliant, the aircraft will need to be delivered with equipment installed that will run autonomously under its own autonomous power source and autonomous Navigation and Data sources (for instance GPS). “This is so that it will independently transmit information from which a position can be determined by the operator at least once every minute, when in distress,” he adds.

For airlines wanting to voluntarily bring fleet commonality for ADT, then hardware installation is ultimately required to achieve desired autonomy. “For ADT capability hardly any operators are complying to ICAO Annex 6 – 6.18 and Appendix 9 recommendations as they see this as a forward fit requirement only,” says Stepin. “The reason being is that very few aviation authorities have adopted this into regulation yet. Instead there are recommendations out to move the effective date to 2023”

To achieve ADT, either the airline needs to decide to accept OEM specific solutions (where most are opting for ELT-DT (Distress Tracking ELTs)) which notify the Search and Rescue in the event of a distress. “Or they choose a lower cost option like SKYTRAC and retrofit their aircraft after their new purchase. The advantage is, they can install this on all their aircraft both forward-fit and retro-fit and have fleet commonality, and be able to receive the position reports directly to their OCC.

“The combination of an ADT system such as SKYTRAC using Iridium, and the ARTEX ELT-DT, ensures both operator and search and rescue get informed simultaneously.”


SITAONAIR has prepared airlines for global aircraft tracking requirements, via the deployment of its ground-based AIRCOM FlightTracker solution. The software guarantees regular flight position updates without requiring any new avionics or modifications, making implementation easy. The solution relies on conventional transmissions from ADS-B Out Mode S transponders, already fitted to most commercial aircraft. “As such, aircraft don’t need to be taken out of service (no cost implications) for maintenance and upgrades,” says Igor Dimnik, Director, Airline OCC and Crew Application Portfolio at SITAONAIR.

AIRCOM Flight Tracker utilises Mode S transponders to provide global tracking coverage. An Alert Module can trigger actions in abnormal situations that escalates tracking to minute-by-minute reports. SITAONAIR
AIRCOM Flight Tracker utilises Mode S transponders to provide global tracking coverage. An Alert Module can trigger actions in abnormal situations that escalates tracking to minute-by-minute reports. SITAONAIR

Today airlines, including Avianca Brazil, Azul, Norwegian Air Shuttle, Singapore Airlines and Vistara, already use AIRCOM FlightTracker, across more than 350,000 flights a month.

“Though a wide variety of technologies exist to track aircraft, they are not consistently integrated,” explains Dimnik. “AIRCOM FlightTracker focuses on connecting the air navigation service provider (ANSP) tracking, including real-time information about problematic weather and expected en route turbulence, among other route planning obstacles.”

AIRCOM FlightTracker aggregates inflight position data from myriad sources – including space-based ADS-B provided by FlightAware and Aireon using the Iridium NEXT satellite constellation – on a single aircraft position display.

“The availability of space-based ADS-B is a game-changer for airlines, and allow them to meet 4D15 and AT requirements,” says Dimnik. “With it, conventional transmissions from ADS-B Out transponders, already fitted to most commercial aircraft, are captured by receivers on new Iridium NEXT satellites, instead of ground based. Most significantly, these aircraft can be tracked from take-off to touchdown anywhere globally, including remote, oceanic or polar regions. The addition of space-based ADS-B means AIRCOM FlightTracker is also equipped to provide one-minute tracking, further enhancing operational awareness and control.”

Additionally, the Alert Module in AIRCOM FlightTracker tracks each flight automatically and generates a warning when an aircraft triggers certain defined conditions. “Alerts can be set up to suit the airline’s needs and to trigger various actions, including uplinks to the aircraft; also messaging actions can escalate as the severity of the condition changes and, in more critical cases, AIRCOM FlightTracker can automatically set up an ADS-C contract for FANS equipped aircraft to provide an additional 1 minute position reporting option for the remainder of the flight,” continues Diminik. All data transmitted in transit is encrypted between Iridium, Flight Aware and SITAONAIR.

In addition, airlines can trigger one-minute position reports from ADS-C using ADS-C contract requests, the same method that ANSPs use to track aircraft over respective control regions.

With the Space-based ADS-B option, AIRCOM FlightTracker is equipped to provide one-minute tracking with no additional communication charges. “Also, the airline does not need to have an Iridium contract because everything is undertaken by and handled through SITAONAIR,” adds Dimnik.

Today, there is an increase in requests for the space-based ADS-B option add-on to AIRCOM FlightTracker, in order to meet GADSS SARPs.

Going Forward

Regarding AT, ICAO indicates that today, most airlines are likely capable. “Operators just had to reconfigure systems to send more data at increased intervals,” adds Stepin. “While on the ground, software systems had the capability to include multiple data sources from various onboard systems, some having space-based ADS-B to enable one-min position reporting.”

For ADT however, a handful of Commercial Transport Category aircraft currently have systems installed which could meet requirement, but OEMs are working to develop viable solutions for standard fit on aircraft. Standards and reports (ARINC 680) have been finalized and regulations are soon to be released by EASA and other aviation authorities. SKYTRAC is experiencing airlines wanting fleet commonality and ease of maintainance.

2020 therefore will see final milestones and goals ahead of the final stages of GADSS becoming effective in 2021. ICAO advises that operators need to establish procedures for the tracking of aircraft (AT and ADT), to be ready to implement the solutions when they become available on newly delivered aircraft. One milestone is the development of the ‘Location of an Aircraft in Distress Repository’ (LADR), which is the DTR referred to earlier. This is a central repository for all distress tracking information, giving access to ATC, search and rescue and any organizations that require it.

The LADR allows operators to meet the Annex 6 Requirement to ‘make position information of a flight in distress available to the appropriate organizations, as established by the State of the Operator’. The LADR was put to tender by ICAO at the end of 2019, and ICAO indicates that a supplier has been selected. Initial prototyping will be completed by April 2020 and review of the functionality will be conducted, after which time the final production version will be developed for the end of 2020.