What happened
On the evening of November 15, 2017, a pilot was conducting a night training flight at Sion Airport (LSGS) in a Cessna 182S, registration HB-CQZ. After completing several circuit patterns, the pilot landed on runway 25 at 18:09 local time. Following instructions from air traffic control, the pilot exited the runway via taxiway Golf.
While taxiing at night, the pilot's attention was drawn to bright red lights on a nearby hangar. In the darkness, the pilot misidentified a strip of blue lights as taxiway Sierra. In reality, the pilot had turned onto the "Route des Aviateurs," a paved road running parallel to the taxiway. While traveling on this road, the right wing of the Cessna 182S struck a fence post, tearing off the aircraft's strobe lights. Shortly after, the wingtip collided with a signpost, causing slight damage to the aircraft and bending the sign.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the lighting infrastructure at the Grely sector of the airport. The investigation found that while taxiways Golf and Foxtrot were brightly illuminated, taxiway Sierra lacked edge lighting for much of its length. Furthermore, the lighting for the access links to the Grely apron extended onto the adjacent road, creating a visual illusion. The investigation also noted a lack of "no entry" signage at the junctions where the road meets taxiway Link 1.
Findings
- The pilot mistakenly used a road instead of the intended taxiway.
- Insufficient taxiway lighting contributed to the pilot's error by making the actual taxiway difficult to identify at night.
- The presence of intense lighting on the road's edge, which was intended for taxiway Link 1, misled the pilot.
- The pilot had previously used different taxiway exits at night, which influenced the incorrect maneuver.