On-Line Data Interchange (OLDI) specification

The Coordination and Transfer (COTR) implementing rule, which contains high level requirements, is complemented by the EUROCONTROL Specification on On-Line Data Interchange, EUROCONTROL-SPEC-0106.

It specifies the facilities and messages to be provided between FDPSs serving ATC units for the purpose of achieving: the notification of flights; the co-ordination required prior to the transfer of flights from one unit to the next; the civil / military co-ordination; situational awareness; the transfer of communication of such flights; support to air-ground data link; co-ordination between Area Control Centres and Oceanic Control Centres.

Edition 4.2 of this EUROCONTROL specification for OLDI has been recognised as a Community specification (CS) after a positive opinion of the Single Sky Committee and after publication of the specification’s reference in the Official Journal of the European Union. Edition 4.3 has been published by EUROCONTROL for the purpose PCP Implementing Regulation as well as the need for clarifications and corrections, and will be submitted to the Single Sky Committee to be recognised as a Community specification (CS).


Flights which are being provided with an ATC service are transferred from one ATC unit to the next in a manner designed to ensure complete safety. In order to accomplish this objective, it is a standard procedure that the passage of each flight across the boundary of the areas of responsibility of the two units is co-ordinated between them beforehand and that the control of the flight is transferred when it is at, or adjacent to, the said boundary.

Where it is carried out by telephone, the passing of data on individual flights as part of the coordination process is a major support task at ATC units, particularly at Area Control Centres (ACCs). The operational use of connections between Flight Data Processing Systems (FDPSs) at ACCs for the purpose of replacing such verbal "estimates", referred to as On-Line Data Interchange (OLDI), began within Europe in the early nineteen eighties.

Common rules and message formats were elaborated and agreed by the agencies concerned and incorporated in Edition 1 of the EUROCONTROL Standard for On-Line Data Interchange; this document, Edition 4.2, has been produced to meet new evolving service requirements and to incorporate feedback from the implementation of earlier versions.

The transfer of OLDI data messages is performed with the Flight Message Transfer Protocol over TCP/IP which is a means of compliance to the Flight Message Transfer Protocol implementing rule.


At the 17th meeting of the Single Sky Committee, it was agreed to request EUROCONTROL to prepare a Specification to be recognised as Community specification on the basis of the EUROCONTROL Standard for OLDI.

An initial plan was developed to address the request.

A draft EUROCONTROL Specification was submitted to a formal written consultation from 28th June 2007 to 17th September 2007, using the mechanisms of the EUROCONTROL Notice of Proposed Rule-Making (ENRPM) process. This was followed by a workshop on 26th October 2007 and the transmission of the final report on 15th November 2007.

Following notification during SSC#24 the OLDI specification required editorial corrections and the final report was re-submitted to the European Commission as Edition 4.1. At SSC#25, Part A of OLDI Edition 4.1 was recognised as Community specification.


EUROCONTROL working arrangement NETOPS agreed with the need to review/update the OLDI specification 4.2 and requested the EUROCONTROL Network Manager to establish a working group to undertake the necessary work within a limited timeframe.
One of the tasks for this group was to assess the present level of compliance with the OLDI standard, using the available data (NOP, LSSIP, IDSG reports) and additional mechanism if required. In that respect, an OLDI deployment questionnaire has been developed and provided to all participating ANSPs on 21 January 2017.  This report contains the main findings from the responses received as well as the recommendations for further actions/next steps.

OLDI Data Exchange Implementation Report 2017 (pdf)