Validation projects

Enhanced short-term conflict alert (STCA) with down-linked parameters

Release: 2013

Reference: -

Location: Milan


The STCA is a ground-based system designed to act as a safety net to prevent loss of separation between aircraft. The system, which can be used in both en-route and TMAs, generates an alert to warn air traffic controllers when separation minima between aircraft look likely to be infringed. The enhanced system makes use of downlinked aircraft parameters (DAP), available through Mode S enhanced surveillance (EHS) (i.e. selected flight level, roll angle/track angle rate), in order to improve the precision of the conflict assessment and to increase the reliability and accuracy of the alerts, while reducing the incidence of nuisance alerts.

Validation results

Exercises in Milan and Rome validated the operational feasibility of enhanced STCA using existing down-link parameters and an enhanced STCA prototype. The results were as follows:

• Improved warning times within the en-route and TMA airspace, leading to increased safety;

• Reduced number of nuisance alarms and maintained rate of genuine alerts;

• Better management of controller workload, generating a higher level of confidence by staff and an increased trust in the system.


The validation results for this solution are conclusive and sufficient to support a decision for industrialisation.