What happened
On June 4, 2023, at 18:12 local time, a serious airprox incident took place at St. Gallen-Altenrhein Airport (LSZR). Two aircraft initiated their takeoff rolls at the same time from opposite ends of the runway: a Moravan N.P. Z 526 ASM (registration HB-TRQ) departing from runway 28 and a Cessna C501 Citation I SP (registration OE-FMK) departing from runway 10.
The single-engine HB-TRQ aircraft lifted off the runway early in its takeoff roll, causing it to fly directly over the oncoming OE-FMK business jet. The Cessna C501 Citation I SP followed shortly after, also lifting off from its respective runway.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) opened an investigation into the event to determine the circumstances surrounding the simultaneous departures. The investigation focused on the flight operations of both the private VFR flight and the IFR flight, noting that the aircraft were operating under different flight rules but shared the same runway environment during the incident.