What happened
On the night of 16 August 2007, a McDonnell Douglas MD-83, registration G-FLTM, was conducting a scheduled passenger charter flight from Lisbon to Dublin. Due to ongoing maintenance on the airport's primary runway, the aircraft was cleared for a non-precision VOR-DME approach to runway 34.
As the aircraft descended toward the threshold, the pilot flying began to deviate significantly to the left of the established approach course. The crew believed they had visual contact with the runway approach lighting system; however, they had actually identified the lights of a hotel located at Santry Cross. This misidentification led the aircraft to descend below the Minimum Descent Altitude (MDA) of 720 feet. At approximately 5.5 nautical miles from touchdown, the aircraft was roughly 200 feet above a nearby building. Upon realizing the aircraft was not aligned with the runway, Air Traffic Control (ATC) instructed the crew to climb, prompting an immediate go-around. The aircraft subsequently transitioned to an ILS approach for runway 16 and landed safely with no injuries to the 112 passengers or 6 crew members.
The investigation
The AAIU investigation examined the flight's descent profile, the cockpit's use of the Digital Flight Guidance System, and the visual environment at night. Investigators reviewed ATC recordings, which captured the crew's query regarding the status of the runway lights and the controller's urgent instruction to turn right and climb.
Technical analysis revealed that while the aircraft was initially tracking the inbound course, the pilot flying selected heading mode instead of VOR tracking at approximately 1,500 feet. This change in flight mode, combined with the visual distraction of ground lights, caused the lateral deviation. The investigation also noted that a following aircraft was able to land on runway 34 without any visual confusion, suggesting the issue was specific to the MD-83's particular approach path and visual perspective.
Findings
- The primary cause of the deviation was the misidentification of hotel lights at Santry Cross as the runway approach lighting system.
- The pilot flying transitioned from VOR tracking to heading mode, which contributed to the aircraft drifting left of the centerline.
- The flight was high on its descent profile due to the late realization that the runway in use had changed from the expected runway 28 to runway 34.
- The presence of additional airfield lighting related to maintenance on the closed runway may have contributed to the crew's visual confusion.