What happened
On December 11, 2013, an Airbus A320-200, registration D-AICE, operated by Condor Flugdienst GmbH, was performing a commercial passenger flight from Hamburg to Tenerife South. Due to severe thunderstorms in the area, the aircraft deviated from its assigned arrival route to bypass a storm cell.
During the approach, lightning strikes had caused malfunctions in the airport's navigation aids, specifically affecting the glide slope and the DME of the ILS for runway 08. Because the glide slope was inoperative, the crew prepared for a non-precision approach (LOC DME) to runway 08. However, the crew mistakenly used the distance from the 'TFS' VOR/DME—located 5.7 NM from the runway—as their primary distance reference to the threshold. This error caused the crew to initiate their final descent at 14 NM from the runway instead of the intended 8.5 NM.
As the aircraft descended, the crew continued below the minimum descent altitude (700 ft) without establishing clear visual references to the runway. The situation was only rectified when the EGPWS issued a 'PULL UP' warning at 435 ft above the terrain. The pilot immediately executed a go-around, and the aircraft subsequently diverted to Fuerteventura before returning to Tenerife to land safely.
The investigation
The CIAIAC investigation examined the cockpit environment, the functionality of the navigation aids, and the communication between the flight crew and Air Traffic Control (ATC). The investigation analyzed the impact of the lightning strikes on the airport's infrastructure and reviewed the accuracy of the information transmitted to the crew regarding the status of the ILS and the DME. The investigators also evaluated the crew's use of standard call-outs and their interpretation of the approach charts during low-visibility conditions.
Findings
- The primary cause of the incident was the erroneable use of the TFS VOR/DME distance as a reference to the runway and the continuation of the approach below the minimum descent altitude without clear visual references.
- Inadequate information transfer regarding the failure of the ILS DME meant the crew was unaware that the primary distance reference was unavailable.
- Inaccurate communication from ATC regarding the status of the approach lights led the crew to believe the lights were inoperative when they were actually functional.
- A lack of active listening by both the flight crew and ATC prevented the detection of the navigation error when the crew reported their position.
- The crew failed to use standard call-outs to report visual contact with the terrain.
- The EGPWS terrain display was not visible on the navigation displays due to radar overlay interference.