What happened
On February 13, 2022, at Locarno Airport (LSZL), a near-collision occurred between a Sonaca S201, registration HB-KGG, and a Mooney M20R, registration N521FH. The incident took place during the initial climb phase under Visual Flight Rules (VFR) in clear weather conditions.
The crew of the HB-KGG, consisting of a flight instructor and a student pilot, was performing touch-and-go training maneuvers. Shortly after the HB-KGG completed a touch-and-go and entered a climb, the pilot of the N521FH lined up on runway 26R and commenced takeoff.
While following the HB-KGG, the pilot of the N521FH maintained a straight course instead of following the published departure route, which requires a right turn after passing the lakeshore. The pilot of the N521FH intended to execute a right turn later to pass the HB-KGG at a safe distance, but the aircrafts' paths intersected. The two aircraft crossed with a horizontal separation of 160 m and a vertical separation of only 20 m. The crew of the HB-KGG only noticed the overtaking aircraft seconds before the close encounter.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the flight paths, radio communications, and pilot intentions. The investigation established that the visibility was excellent and that the pilot of the N5021FH had twice misidentified the runway on the radio frequency, though both pilots maintained visual contact with each other.
Findings
- The pilot of the N521FH did not follow the prescribed departure route, which involves a specific sequence of turns after passing the lakeshore.
- By maintaining a straight course behind the slower HB-KGG, the pilot of the N521FH shortened the flight path and increased the rate of approach.
- The pilot of the Mooney underestimated the speed of the approach and the risk of the closing rate.
- A discrepancy in perception existed between the crews: the pilot of the faster aircraft believed the situation was controlled because the HB-KGG was in sight for a long period, whereas the HB-KGG crew only detected the overtaking aircraft moments before the separation loss.