What happened
On March 14, 2012, an Airbus A320-200, registration EI-DEA, operating as an Air Lingus flight from Cork to Barcelona, entered a holding pattern due to deteriorating visibility. The runway visual range (RVR) for runway 25R at Barcelona El Prat Airport had fallen below the 400m minimum required by the crew for a Category II approach. Although the crew requested a change to runway 25L, which supported Category III operations, air traffic control (ATC) denied the request, stating that the parallel runway configuration must be maintained as long as the RVR remained above 300m.
After holding for approximately 30 minutes, the crew attempted to divert to Valencia. During the diversion, a brief improvement in RVR prompted a decision to return to Barcelona. However, during the final approach, the RVR again dropped below the required minimums, forcing the crew to execute a missed approach. The crew then requested vectors to Girona, their planned alternate. However, they were informed by ATC that Girona had no available parking due to a high volume of diversions.
Facing rapidly decreasing fuel levels, the crew declared an urgency situation (PAN PAN) at 20:15 UTC. Following this declaration, the Barcelona tower changed the configuration and authorized the aircraft to land on runway 25L. The aircraft landed without further incident.
The investigation
The CIAIAC investigation examined the communications between the aircraft, the Barcelona tower, and the Area Control Center (ACC). The investigation revealed that the tower supervisor's decision to refuse the runway change was driven by a literal and rigid interpretation of poorly written local procedures. Furthermore, the investigation found that the information regarding the lack of parking at Girona was inaccurate; the airport actually had approximately 10 available stands, but a breakdown in communication and the use of non-standard terminology led the controller to believe the airport was full.
Findings
- The primary cause was the tower's initial decision to maintain the runway configuration, which prevented the aircraft from landing at its destination.
- The tower supervisor's decision was influenced by ambiguous procedural text and exacerbated by high workload and communication issues.
- The crew's fuel margins were significantly reduced by the prolonged holding period and the failed diversion attempt.
- Inaccurate information regarding the availability of parking at Girona prevented the crew from safely diverting to their alternate.
- Low visibility procedures at the airport did not explicitly account for the specific minimum RVR requirements for each individual runway's approach category.