Major developments towards implementation of the global aircraft-in-distress service


In 2024 the International Civil Aviation Organization (ICAO) and EUROCONTROL will together launch the full operational version of the Location of an Aircraft in Distress Repository (LADR), as part of a global initiative to track aircraft in distress at all times.

On June 15 this year, EUROCONTROL began testing the initial stage of the Location of an Aircraft in Distress Repository (LADR) system, one of the core elements of ICAO’s work to ensure that key aviation stakeholders, including search and rescue operators, have up-to-date information related to the last known position of an aircraft. An initial operational version will be available at the end of 2023, with further development in early 2024.

The LADR system (see “EUROCONTROL’s role in enabling GADSS via LADR and OPS CTRL”) is being developed within the agency’s Network Management Directorate and the beta version “allows contributors to connect to the system, to provide data about the last known position,” says Anastasiia Sobchenko, Common Services Expert in the Network Manager Directorate. “In this first step we are working with contributors to ensure they can connect to the system, and we receive data from them.”

The ICAO Global Aeronautical Distress and Safety System (GADSS) has four core elements: aircraft tracking, distress location, post-flight localisation and data recovery.

“The aircraft tracking requirements became applicable in 2018,” says Ian Knowles, Technical Officer at the Operational Safety Section of the Air Navigation Bureau of ICAO. “Broadly speaking, this requires a 15-minute position report from an aircraft when it’s in oceanic airspace. If an aircraft is operating in airspace controlled by an air navigation service provider (ANSP) then we can use that automated report.”

To assist in the implementation of these standards, the Normal Aircraft Tracking Implementation Initiative (NATII) was established, and group members decided there needed to be a better means of communication between aircraft operators and ANSPs, which led to the establishment of the OPS Control Directory. “If an aircraft operator has a reason to doubt the safety of an aircraft it needs to know who to get in touch with,” says Ian Knowles. “So the OPS Control Directory was established in direct response to that initial first standard.” EUROCONTROL will host the Ops Control Directory as part of the LADR system, where the usage of OPS Control will be extended to all users of LADR.

The deadline for fitting new aircraft – produced from 1 January 2024 onwards – with distress equipment tracking requirements will be 1 January 2025, following a delay to the initial planned implementation date as a result of the COVID pandemic.



“One of our EUROCONTROL colleagues, Henk Hof, was leading the development of the GADSS concept and in 2021 we contacted ICAO to propose our support for the LADR development and hosting,” says Anastasiia Sobchenko. “Many European passengers lost their lives in the Air France 447 and Malaysia Airlines 370 disasters, so our response was based on our commitment to undertake additional work to increase passenger safety, supported by all relevant stakeholders including the Network Directors of Technology (NDTECH).”

The LADR project sits within the Network Manager Directorate Infrastructure Division and is being developed together with the Technology Division. “We are developing LADR using agile methodology,” says Anastasiia Sobchenko. “We have broken down the project into smaller phases, emphasising collaboration and continuous improvement, developing LADR in an evolutionary way. This year we will develop the repository and next year scale it up to bring additional functionality to the users.”

The development timelines are ambitious. “But we also try to be very pragmatic, to see what we can do today, what we can improve tomorrow, not to focus on the full scope with many add-ons from the outset,” says Anastasiia Sobchenko. “We focus on the core requirements of the performance specifications document – Functional Specifications for the Location of an Aircraft in Distress Repository (LADR) (Doc 10150) – and with ICAO identified priorities for the LADR services, what needed to be done at the beginning, at the second stage and then identified the essentials that LADR cannot work without.”

A key requirement has been to engage all stakeholders on a regular basis. To understand better how users will be using the system, the EUROCONTROL LADR team involved more than 30 stakeholders including airlines, ANSPs, search and rescue units and States authorities, with representation from all parts of the world to collect their ideas and feedback.

EUROCONTROL’s role in enabling GADSS via LADR and OPS CTRL

In May 2023 ICAO Secretary General Juan Carlos Salazar and EUROCONTROL Director General Raúl Medina signed an agreement for the development and hosting of a Location of an Aircraft in Distress Repository (LADR) and an Operational Control Directory (OPS CTRL), key parts of the ICAO Global Aeronautical Distress and Safety System (GADSS) that covers autonomous distress tracking equipment on aircraft and improved systems and procedures to collect and share last known aircraft location information.

LADR and the OPS CTRL elements will facilitate the exchange of information between air operators, air navigation service providers and rescue coordination centres.

“Implementation of LADR will allow search and rescue services to better employ their resources in a timely manner to the most effective locations, thereby assisting in their mission to save lives,” said ICAO Secretary General Juan Carlos Salazar at the agreement signing ceremony.

The GADSS concept was launched following two high-profile incidents involving airliners that went missing, triggering complex and highly costly search efforts: the crash of Air France Flight 447 on 1 June 2009 and the disappearance of Malaysia Airlines flight 370 on 8 March 2014.

LADR will allow data submissions from accredited contributors to ensure all information related to the location of an aircraft in distress from suitably equipped aircraft is stored and made available to users. In case of an “aircraft in distress” anywhere, anytime around the globe, LADR will provide a single point of access to the required information and notify the appropriate stakeholders, including aircraft operators, air navigation service providers and search and rescue, of a potential event. An initial version of LADR with core-functionality is expected to be delivered by the end of 2023, and an enhanced and scaled-up version that conforms with existing requirements is expected to be delivered by November 2024.

GADSS contains three main elements: aircraft tracking; location of an aircraft in distress (achieved through autonomous distress tracking (ADT) of aircraft in flight), and post-flight localisation and recovery (PFLR). All aircraft of a maximum certificated takeoff mass of over 27 000 kg for which the individual certificate of airworthiness is first issued on or after 1 January 2023 must autonomously transmit information from which a position can be determined by the operator at least once every minute, when in distress, in accordance with Appendix 9. 6.18.2.

“We used performance-based standards for this system,” says Ian Knowles. “We set the requirements of the system and left people to come up with different ways of meeting those requirements. The key objective is for the system to be triggered when a flight is in a distress condition, which is defined by EUROCAE document ED-237. The system will then transmit position information every minute. There are a number of different ways of doing that and at least three manufacturers that can meet all of the requirements.”

“It’s a technology-agnostic approach,” says Anastasiia Sobchenko. ”Jointly with ICAO and potential contributors to LADR, we have developed a LADR FIXM schema which will allow LADR contributors to provide data in a standard format, LADR to compile it and provide it to stakeholders in a clear way.”

In terms of the data, LADR is collecting both mandatory and optional elements. For the mandatory data there is a unique aircraft identifier – the three-letter designator from the State plus an aircraft registration, the aircraft’s 24-bit address or flight callsign, among others. Other core elements are latitude and longitude and time-at-the-reported-position.

“We also want to know who is sending us the information, so not just the aircraft but the manufacturer of the system,” says Ian Knowles. “That can be very useful information in finding out what’s happening if the system stops transmitting or we miss a signal. Ground speed and the heading are also important because that will direct the search and rescue services to the most likely destination or final impact point.”

“Once we receive the data through the LADR system we validate it,” says Anastasiia Sobchenko. “We then immediately make it available to operational stakeholders, so they all receive this information in the same format, in the same way and at the same time. The LADR system identifies to which FIRs this data belongs, to which airline and search and rescue unit it belongs – so they don’t have to sit 24/7, watching LADR. They receive a notification and then react.”

“In an ideal world we are building a system which would have no notifications because these will only be triggered if an aircraft is in distress,” says Ian Knowles. “It would be great if we never have to use it.”

Ian Knowles
Ian Knowles
Technical officer, operational safety section
Anastasiia Sobchenko
Anastasiia Sobchenko
Common Services Expert, Network Management Directorate

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