ETCS FIS Juridical Recording (Subset-027)

Scope

UNISIG functional interface specification for juridical recording in ERTMS/ETCS, defining the events and data the on-board juridical recording function must capture and the format in which they are made available for download and analysis. Version 4.0.0 is mandated as index 005 of the single set of specifications in Annex A of the 2023 CCS TSI, and is used by on-board suppliers, accident investigators and safety authorities when analysing recorded ETCS operational data.

SUBSET-027 is UNISIG's functional interface specification for juridical recording in ERTMS/ETCS, defining the operational events and associated data that the on-board juridical recording function must capture during train movement, and the format in which that recorded data must be made available for download and subsequent analysis. Juridical recording serves the same purpose in an ETCS-fitted train as a flight data recorder does in aviation, giving accident investigators and safety authorities a standardised, auditable record of what the ETCS system and the driver did in the period leading up to an incident. Version 4.0.0 is mandated as index 005 of the single set of specifications in Annex A of the 2023 CCS TSI, meaning any ETCS on-board unit placed in service under the current TSI must implement juridical recording exactly as this specification defines it. On-board equipment suppliers implement the specification's recording requirements directly in their products, while accident investigators and national safety authorities rely on the standardised data format when analysing recorded ETCS operational data following an incident or during routine safety oversight. It works alongside the other mandatory CCS TSI Annex A specifications, including the System Requirements Specification, which defines the operational events the juridical recorder must be able to capture.