What happened
On February 6, 2019, a near-collision occurred near Valkeakoski involving a Finnish Air Force Learjet 35 A/S and a DJI Phantom 4 Pro Obsidian drone. The military aircraft was conducting a training flight departing from Tampere-Pirkkalan airport. Simultaneously, the Pirkanmaa Rescue Department was conducting a joint training exercise for forest search and rescue operations using the drone.
At approximately 12:09 local time, the two aircraft passed within close proximity. The drone was flying at an altitude of approximately 77 meters AGL, while the Learjet was flying lower, at approximately 69 meters AGL. The lateral separation between the two aircraft was roughly 60 meters. The drone operator reported hearing a loud, roaring sound from behind and observed the aircraft passing directly overhead. No collision occurred.
The investigation
The investigation examined the actions of the drone pilot, the air traffic controllers, and the communication procedures used during the exercise. The investigation established that the drone operator had notified Tampere-Prickala tower of the planned flight, including the location, duration, and altitude (under 150 meters). However, the notification was received by an air traffic controller who was currently on break.
While the controller confirmed via the Droneinfo application that the drone activity was within uncontrolled airspace (G-class) and below the approach area, they failed to pass this information to the active controller on duty. Furthermore, the controller informed the drone operator that no specific permission was required for the flight but did not disclose the flight path of the Learjet currently on a training mission.
Findings
- The primary cause of the near-collision was the failure to communicate critical flight information between air traffic controllers during a shift change.
- The controller on break received the drone operator's notification but did not relay the details to the active controller.
- The active controller was unaware of the drone's presence because the information was not passed on.
- The drone operator's notification was received by an off-duty controller, which led to a breakdown in the operational awareness of the active staff.
- There were deficiencies in the Droneinfo application, which lacked the ability to handle advance flight notifications or provide real-time dynamic airspace information.