What happened
On October 22, 2017, a Piper PA-3/4-220T, registration N101FM, was conducting an IFR flight from Heubach, Germany, to Strasbourg-Entzheim, France. The pilot was operating in instrument meteorological conditions (IMC) and was descending toward FL80. Simultaneously, an Airbus A320-200, registration D-ABHJ, operated by Air Berlin, was climbing from Baden-Baden, Germany, toward Hamburg, Germany.
At approximately 14:50 UTC, the air traffic controller identified a potential conflict, noting that the N101FM was 1,000 feet above its assigned altitude and positioned near the climbing D-ABHJ. The controller instructed the A320 crew to reduce their rate of climb and directed the PA-34 pilot to climb immediately to FL80. However, the pilot of the N101FM failed to climb and continued the descent.
Following emergency instructions from the controller, the A320 crew executed a left turn. Shortly after, the A320 crew reported a TCAS resolution advisory (RA), likely a descent command, and began descending. The two aircraft reached a minimum vertical separation of approximately 750 feet. The PA-34 reached its lowest point at FL74 before beginning a climb.
The investigation
The investigation focused on the pilot's actions and the aircraft's technical performance. The pilot of the N101FM reported experiencing significant difficulties with the autopilot, which failed to follow the descent clearance. Additionally, the pilot noted fluctuating vertical speed indicator readings. The pilot, who had recently acquired the aircraft, was still becoming familiar with its conventional instrumentation compared to the "glass cockpit" systems he was accustomed to. The investigation also noted that the pilot's attention was heavily focused on manual flight control due to these technical issues, which hindered his ability to process controller instructions.
Findings
- The pilot had limited experience flying this specific aircraft type, having only flown it for approximately 18 hours.
- The pilot had very limited experience operating in IMC (only 2 hours of actual IMC flight time).
- The pilot lacked familiarity with the aircraft's specific navigation system.
- Unexpected behavior from the aircraft's navigation system contributed to the pilot's loss of situational awareness during a critical phase of flight.
- A system failure in the navigation or autopilot equipment was possible, although a specific malfunction could not be definitively established during the investigation.