What happened
On July 8, 2015, at approximately 10:50 UTC, an air traffic controller at Bydgoszcz-Szwederowo Airport (EPBY) issued takeoff clearance for a Cessna 172 positioned at the holding point for runway 26. As the pilot began taxiing toward the runway, the pilot of a Piper PA42-720 Cheyenne 3 reported being three nautical miles from the runway threshold on the final approach.
Upon receiving this report, the controller reassessed the situation. Due to the proximity of the approaching aircraft and the slow taxi speed of the Cessna 172, the controller instructed the Cessna 172 to stop and backtrack to the holding point on taxiway A. The takeoff for the Cessna 172 was subsequently delayed until 10:55 UTC to allow the Piper PA42-720 Cheyenne 3 to land safely.
The investigation
The investigation examined the controller's decision-making process and the technical capabilities of the airport's radar surveillance. The investigation established that the controller was monitoring the traffic and had initially assessed the takeoff as safe. However, the controller's subsequent decision to cancel the clearance was based on a re-evaluation of the distance between the two aircraft and the taxi speed of the departing aircraft.
Investigators noted that the Piper PA42-720 Cheyenne 3 was traveling at a high ground speed of approximately 190 knots, which could have led to a misleading perception of the closing distance. Furthermore, the investigation found that the aircraft temporarily disappeared from the controller's radar display. It was determined that due to the placement of radar antennas, aircraft flying below 3,000 feet AGL are often not visible on the controller's display, a factor that increases the risk of unforeseen events.
Findings
- The controller's decision to interrupt the takeoff was correct and prevented a potential conflict.
- Radar coverage limitations at the airport meant that smaller aircraft at low altitudes are frequently not visible on the controller's radar screen.
- The high ground speed of the approaching Piper PA42-720 Cheyenne 3 could have caused a misjudgment of the distance to the runway threshold.
- The event did not meet the formal definition of a runway incursion.