What happened
On the night of 16 August 2007, a McDonnell Douglas MD-83, registered G-FLTM, was operating a passenger charter flight from Lisbon to Dublin. During the approach to Dublin Airport, the aircraft was directed to use runway 34 because maintenance work was being performed on the main runway.
As the aircraft reached approximately 5 nautical miles from the touchdown point, it began drifting left of the established approach path. During this deviation, the aircraft descended beneath the Minimum Descent Altitude (MDA) without the crew successfully identifying the active runway visually. Air Traffic Control (ATC) intervened, instructing the crew to turn right and climb to a safe altitude. The aircraft was subsequently provided with radar vectors for an approach to runway 16, which it completed without further issues.
The investigation
Following the incident, the AAIU performed several approach simulations to runway 34 to determine why the aircraft had strayed from its course. The investigation focused on the visual environment during night operations. Investigators identified that a 16-storey building located at Santry Cross featured four fixed red obstacle lights on its roof. At night, the light pattern from this structure was found to closely mimic the red and white light configuration of a standard runway approach lighting system.
Findings
- The primary cause of the deviation was the visual confusion caused by obstacle lighting on a building at Santry Cross, which resembled runway approach lights.
- The aircraft descended below the MDA without the crew having the required visual contact with the runway environment.
- Weather conditions during the approach were otherwise good.