Always update and switch on collision warning systems

On June 12, 2021, there was a collision between a motorized aircraft and a glider west of Piz Neir (GR), resulting in the deaths of all occupants. Thefinal report (german) of the Swiss Transportation Safety Investigation Board (STSB) was published this week. The investigation revealed that technical, human and operational aspects played a role in collision prevention, which had already been identified in previous investigations and addressed with corresponding safety recommendations. STSB and Staysafe are therefore issuing the following comprehensive safety notice to remind pilots of ways to improve collision avoidance in visual flight.

Sense and avoid
The “see and avoid” principle for collision avoidance does not always work satisfactorily. For this reason, it should be supplemented by technical and operational aids for collision avoidance in the direction of a “sense and avoid” principle. The following can serve this purpose: Mutually compatible collision warning devices; Transponder/ADS-B out; Collision warning lights; Conspicuous coloring; Regular and meaningful position reports on the radio.

Figure: Illustration of the main technical safety nets that remained ineffective in the present case, page 30 Final Report No. 240

Useless without updated software
Technical aids for navigation or collision avoidance are only useful if they are correctly installed and maintained to ensure that they function properly. In particular, this also includes regular software and database updates or, in the event of a device change, appropriate recoding so that the aircraft can also be clearly identified for SAR services. We will address these aspects in a separate article.

Figure: Chronological list of events during the search and rescue, page 43 Final Report No. 240

Furthermore, these aids can only be effective if their users are aware of how they work and their possibilities and limits, so that they can use them adequately and effectively to support collision avoidance.