What happened
On September 4, 2017, at 08:50 UTC, a runway incursion occurred at Jerez Airport involving two training aircraft. The first aircraft, a Piper PA-28-161 with registration EC-IOT, was instructed by air traffic control to line up and wait on runway 20 at intersection E3. While this aircraft was positioned on the runway, the controller authorized a second aircraft, a Cessna 172 with registration D-EVOC, to perform a touch-and-go maneuver on the same runway.
Upon landing, the pilot of the Cessna 172 observed that the runway was occupied by the Piper PA-28-161 and promptly stopped the aircraft approximately 30 meters away from the stationary plane. No injuries were reported, and no damage was sustained by either aircraft.
The investigation
The investigation established that the Piper PA-28-161 was positioned at intersection E3, a location that placed it directly behind a structural support pillar of the control tower's viewing canopy. This positioning rendered the aircraft invisible to the controller from their primary vantage point. Although the controller attempted to scan the runway by moving left and right, the aircraft remained obscured by the pillar.
During the interval between communicating with the first aircraft and authorizing the second, the controller engaged with other traffic and checked transponder codes. The investigation found that the controller mistakenly believed the Piper PA-28-161 had already departed. This confusion was compounded by previous instances of radar tag errors in the automated system, leading the controller to assume the lack of a radar target for the first aircraft meant it was no longer on the ground. Additionally, the pilot of the aircraft on the runway did not take action or alert the tower when they heard the authorization for the second aircraft to perform a touch-and-go.