What happened
On August 13, 2017, at the Akeno Sky Sports Club temporary airfield in Ibaraki Prefecture, a serious incident occurred involving two privately owned aircraft. The first aircraft, a Cessna 172 H Ram (registration JA3353), had completed its first of three planned practice circuits. After landing at 10:36 JST, the pilot taxied the aircraft toward the runway threshold to prepare for a second takeoff roll.
While the pilot of JA335 and was checking instruments and aligning the aircraft for departure, an experimental Sakamoto SS-9 (registration JX0157) appeared overhead. At approximately 10:38 JST, the Sakamoto SS-9 landed on the temporary runway, coming to a stop roughly 20 meters directly ahead of the stationary Cessna 172 H Ram. The pilot of the Cessna was unaware of the approaching aircraft until it was nearly on top of them. Following the close encounter, the pilot of the Cessna taxied toward the experimental aircraft to investigate, noting that the Sakamoto SS-9 lacked a communication radio. After the Cessna completed its second takeoff, the experimental aircraft departed the area toward the southeast.
The investigation
The Japan Transport Safety Board (JTSB) investigated the incident, examining flight histories, GPS data from a mobile phone, and witness statements. The investigation established that the pilot of the Sakamoto SS-9 had not obtained the necessary permissions under the Civil Aeronautics Act for the flight, nor had they secured permission from the airfield club to use the temporary runway.
Investigators also reviewed the airfield's management rules, which prohibit landing on a final approach course if another aircraft is attempting to take off. The investigation found that the pilot of the Sakamoto SS-9 believed the Cessna 172 H Ram was positioned outside the active runway area, leading to the decision to land.
Findings
- The pilot of the Sakamoto SS-9 lacked an accurate understanding of the temporary airfield's specific runway boundaries and characteristics.
- The pilot of the Sakamoto SS-9 incorrectly perceived that the Cessuna 172 H Ram was stopped outside the runway limits, which prompted the landing.
- The flight involving the Sakamoto SS-9 was conducted without required regulatory permissions for aircraft operation or airfield use.
- The Sakamoto SS-9 was not equipped with a communication radio, preventing coordination between the two pilots.