What happened
In early 2012, two distinct incidents occurred within the Eindhoven Special Rules Zone (SRZ) involving departing commercial aircraft and other traffic.
In the first event on March 9, 2012, an Airbus A320, registration HA-LWA, departed Eindhoven Airport. During its climb, the aircraft encountered a Cessna 172, registration OO-WVS, which was crossing the zone. Due to a misunderstanding regarding the altitude of the piston aircraft, the two planes were placed on converging tracks. The aircraft eventually passed within 0.4 NM horizontally and 15 .500 feet vertically.
In the second event on March 21, 2012, an Airbus A320, registration HA-LWK, was climbing after takeoff when it encountered a Piper Cheyenne II XL, registration D-IBGC. The air traffic controller instructed the Piper Cheyenne II XL to turn to a heading of 360 to avoid the airliner. However, this maneuver placed the aircraft on a direct collision course with the departing Airbus A320. The crew of the Airbus A320 received a TCAS RA and responded by descending. The minimum separation reached was 0.5 NM laterally and only 300 feet vertically.
The investigation
The Dutch Safety Board examined the airspace structure and communication procedures in place during the SRZ era. The investigation focused on how the presence of mixed controlled and uncontrolled traffic, combined with increasing flight volumes, contributed to these close encounters. Investigators analyzed the radar data, radio communications, and the specific instructions provided by Dutch Mil Info controllers during both events.
Findings
- In the first incident, the controller lacked accurate altitude information for the Cessna 172 because the transponder altitude readings were not clear, leading to an incorrect assumption that the aircraft was at 2500 feet.
- In the second incident, the controller's instruction to the Piper Cheyenne II XL to turn north actually directed the aircraft toward the flight path of the departing airliner.
- The use of separate radio frequencies for IFR and VFR traffic prevented the crews from hearing each other and building a shared mental picture of the surrounding traffic.
- The controller was unaware of the specific movement freedom of VFR aircraft within the SRZ and the high closing speeds involved.
Safety action
Following these occurrences, the Eindhoven Terminal Area (TMA) was established in May 2013. This new C-class airspace structure was designed to better safeguard operations by providing mandatory two-way separation between both IFR-IFR and IFR-VFR traffic.