What happened
On April 27, 2014, at Valencia Airport, a sequence of arrivals and a departure led to a loss of required separation between two aircraft. The Air Nostrum Tower controller had planned a sequence to interleave the departure of a Ryanair Boeing 73 and-800, registration EI-EBG, between the landings of two Air Nostrum aircraft: a Bombardier CRJ900 (EC-JZS) and a Bombardier CRJ200, registration EC-HPR.
Following the landing of the first aircraft, the controller authorized the Ryanair flight to line up and wait for immediate takeoff once the runway was clear. However, the preceding aircraft took longer than anticipated to vacate the runway. As the distance between the arriving EC-HPR and the departing EI-EBG decreased below regulatory limits, the controller authorized the takeoff of the Ryanair aircraft while the Air Nostrum flight was still on final approach. Consequently, the CRJ200 crossed the runway threshold before the departing Boeing 737-800 had cleared the opposite threshold, violating established separation standards.
The investigation
The CIAIAC investigation examined the actions of the air traffic controller, the flight crews, and the existing aerodrome procedures. The investigation found that the controller had instructed the first arriving aircraft to accelerate its taxi to vacate the runway, but the crew of that aircraft did not properly acknowledge the instruction or indicate an inability to comply. Furthermore, the controller's instructions to the Ryanair crew were inconsistent, initially requesting "immediate takeoff" but then instructing them to "enter and line up," which contradicted standard procedures for immediate departures.
The investigation also revealed that the controller had the opportunity to alter the sequence by requesting a missed approach for the arriving EC-HPR when the separation began to erode, but chose to proceed with the original plan. The investigation noted that the Ryanair crew delayed their takeoff roll by approximately 10 seconds, as they were waiting for the runway to be confirmed clear.
Findings
- The primary cause of the incident was the deficient management of the takeoff and landing sequence, which resulted in a failure to maintain the separation distances required by the Air Traffic Regulations (RCA).
- A contributing factor was the failure of the crew of the preceding aircraft (EC-JZS) to properly read back the instruction to vacate the runway or communicate their inability to comply.
- The investigation identified a lack of specific, written procedures for Valencia Tower controllers regarding the exact timing or position at which a departure can be authorized between two arrivals without risking a separation loss.
- The reliance on the subjective skill of individual controllers to manage traffic flow, rather than standardized distance or time references, represents a significant operational vulnerability.