STCA (Short Term Conflict Alert) is a ground system designed and deployed to act as safety net against the risk of having collisions between aircraft during airborne phases of flight. STCA can be used in both en-route and TMA surveillance environments.

The difficulty of STCA development lies in the need to avoid having a high nuisance alert rate, while still making sure that real conflicts always trigger an appropriate and timely warning. Specific tuning is necessary for STCA to be effective in the TMA, in order to account for lower separation minima, as well as increased frequency of turns, climbs and descents.

It is therefore recognised that STCA may not be operationally usable in some dense TMA operations, because the nuisance alert rate generated by a linear STCA algorithm is evaluated to be too high.

The aim of this Objective twofold:
• To address the implementation of STCA functionality in TMAs
• For the TMA where, due to their complexity, the linear STCA algorithms are not fit for purpose, to address the improvement of the STCA functionality. This could be achieved by using multi-hypothesis algorithms, or other technical solutions ensuring earlier warning and lower nuisance alert rates related to steady and manoeuvring aircraft, in comparison to linear STCA algorithms.

NOTE 1: the scope of this Objective is limited to the deployment of the STCA functionality in TMAs. The (former) objective ATC02.2 which was addressing both en-route and TMA environments had its scope reduced to en-route allowing to consider it as achieved.

NOTE 2: SLoA ATC2.9-ASP02 does not have an associated FOC date and should be considered for specific local needs (refer to the description of SLoA below).

NOTE 3: : In certain more complex environments specific tuning is necessary for STCA to be effective especially in the terminal airspace in order to account for lower separation minima, as well as increased frequency of turns, climbs and descents. In these situations, the STCA may need to be improved with e.g. the use of multi-hypothesis algorithms, aiming to reduce the number of false and nuisance alerts compared to existing technologies, while maintaining the detection of genuine alerts (SLoA STCA02.9-ASP02). The improved STCA algorithms lead to more precise warnings and fewer false and nuisance alerts when compared against existing STCA technology.

NOTE FOR MILITARY AUTHORITIES: It is the responsibility of each military authority to review this Objective IN ITS ENTIRETY and address each of the SLoAs that the military authority considers RELEVANT for itself. This has to be done on top and above of the review of "MIL" SLoAs which identify actions EXCLUSIVE to military authorities.

Edition

2022

Stakeholders

Air Navigation Service Provider

Type

SESAR

Scope

ECAC+

Status

Achieved