Incident Overview
On 22 October 2017, at approximately 14:51 UTC, a Piper PA-34-220T (registration N101FM) and an Airbus A320-200 (registration D-ABHJ) were involved in a loss of separation while under the control of Strasbourg Approach. The incident occurred during the PA-34's descent and the A320's initial climb. No damage was reported to either aircraft.
Flight Details
The Piper PA-34, operated privately and with a single pilot on board, was conducting an IFR flight from Heubach, Germany, to Strasbourg-Entzheim, France. The pilot was descending through cloud layers in IMC. The Airbus A320, operated by Air Berlin, was performing a commercial passenger flight from Baden-Baden, Germany, to Hamburg, Germany. Its crew consisted of a captain, first officer, and cabin crew with passengers.
Sequence of Events
At 14:44, the PA-34 pilot was cleared to descend to FL80 on heading 275 for an ILS approach to runway 23, which he acknowledged. At 14:49, the A320 crew was cleared to climb initially to FL70 and turn left to heading 045. One minute later, at 14:50:14, the controller instructed the A320 to reduce its rate of climb, advising of traffic (the PA-34) 5 nautical miles east, 1,000 ft above its cleared altitude.
At 14:50:26, observing the PA-34 descending through FL80, the controller asked the pilot to confirm his altitude and then directed him to immediately climb back to FL80. The pilot acknowledged but did not climb. At 14:50:40, the controller instructed the A320 to turn left immediately to heading 045, and seconds later directed the PA-34 to turn left to heading 210. The A320 complied, while the PA-34 turned right toward the north, contrary to the instruction.
At 14:51:25, the controller asked the PA-34 pilot about the situation. The pilot responded that he was having autopilot difficulties and was "trying to maintain the aircraft." The controller then used emergency phraseology to instruct him to climb to FL80, but the pilot continued descending. At 14:51:51, the A320 crew announced a TCAS Resolution Advisory (RA) and began to descend. The minimum vertical separation reached was approximately 750 ft, with the PA-34 descending to FL74 before beginning to climb. The A320 crew then reported the conflict resolved and resumed their heading to FL70.
Subsequently, the controller provided further instructions for the PA-34 to intercept the ILS, and the pilot eventually landed on runway 23 at 15:02.
Pilot Background and Testimony
The PA-34 pilot, aged 36 and residing in Germany, held a French private pilot license (SEP) issued in 2008 and a U.S. commercial pilot IFR multi-engine license from June 2017. He had 276 total flight hours, including 24 on the PA-34 and 2 in actual IMC. He had purchased the aircraft a few days prior and flown it less than 18 hours.
The pilot stated he bought the aircraft for professional use and was accustomed to glass cockpit instrumentation, making the conventional instruments of the PA-34 unfamiliar. On the day of the incident, he was flying to Strasbourg for dual instruction to familiarize himself with the aircraft.
He reported that during the flight, the autopilot did not follow the descent clearance to FL80, and the vertical speed indicator showed fluctuating readings. He resumed manual control. He also noted receiving numerous instructions from the controller in a short time, some seemingly contradictory. Being in IMC and unfamiliar with the aircraft, he focused on flying at the expense of communications.
After the incident, the pilot flew again and encountered additional autopilot malfunctions. The GARMIN 430 GNSS unit was sent to a maintenance workshop, and a few weeks later replaced with a glass cockpit system.
Conclusions
The BEA concluded that the controller identified the potential conflict immediately and issued instructions using emergency phraseology. The controller was unaware of the PA-34 pilot's difficulties. The incident was contributed to by the pilot's low experience on the aircraft, low experience with the navigation system, low IMC experience, and an unexpected behavior of the navigation system that surprised the pilot during a dynamic phase in IMC.
Safety lessons noted that the controller's instructions to the A320 crew and the A320 crew's compliance with the TCAS RA to descend prevented a dangerous situation.