EUROCONTROL Mode S and ACAS Programme Advice

Mode S - Flight Plans and Transponders

It is essential that:

  • Flight crews and aircraft dispatchers correctly enter details of aircraft identification in item 7 of the flight plan and that this is exactly replicated on board the aircraft.
  • The item 10 entry in the flight plan should correspond with the aircraft’s transponder functionality. Currently, over 30% of item 10 entries are incorrect.
  • Incorrect data of this kind, whilst not a direct safety hazard by itself, does nevertheless have knock-on safety implications of increased workload, creates confusion, and reduces the potential for realising the well documented safety benefits of Mode S surveillance.



© European Organisation for Safety of Air Navigation (EUROCONTROL) March 2007. This alert is published by EUROCONTROL for information purposes. It may be copied in whole or in part, provided that EUROCONTROL is mentioned as the source and to the extent justified by the non-commercial use (not for sale). The information in this document may not be modified without prior written permission from EUROCONTROL. The use of the document is at the user’s sole risk and responsibility. EUROCONTROL expressly disclaim any and all warranties with respect to any content within the alert, express or implied.


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