Created Tuesday, Jan 16th 2024 18:34Z, last updated Tuesday, Jan 16th 2024 18:34Z
A Ryanair Boeing 737-800, registration EI-DYO performing flight
FR-9366 from Barcelona,SP (Spain) to Bologna (Italy) with 166 passengers and 6 crew, was taxiing for departure and had been cleared to cross runway 24R at the extension via taxiway S14. The stop bars were extinguished and the crew proceeded to cross the runway when ground control instructed them to stop. The crew stopped the aircraft on the runway extension.
A Delta Airlines Airbus A330-300, registration N803NW performing flight DL-169 from Barcelona,SP (Spain) to New York JFK,NY (USA) with 293 passengers and 13 crew, was departing Barcelona's runway 24R and overflew the Boeing 737-800 on the runway extension at about 700 feet AGL.
Spain's CIAIAC released their final report concluding the probable causes of the incident were:
The investigation has established that the incident was caused by a failure to adhere to procedures on the part of the local arrivals controller, who neglected to stop the flow of traffic across the S14 bypass taxiway.
The following factors are thought to have contributed to the incident:
- The design of the non-preferential runway take-off checklist.
- The ergonomics of the lighting control and indicating system
The CIAIAC analysed:
According to Annex B of the Barcelona-El Prat Tower Operating Manual, the local arrivals controller (LCL ARR) is responsible for runway 24R when it is used for non-preferential landings and take-offs. If a non-preferential landing or take-off is requested, the controller must notify the north ground movement controller (GMC N) before they expect it to take place. Later, just before the take-off, they must switch on the bypass stop bar. We were able to confirm, through the AENA stop bar usage records, that the stop bar was not illuminated until aircraft DAL169 was already accelerating along the runway (at 14:07:44), some time after the take-off clearance for the non-preferential aircraft (which was issued at 14:06:44). No error was detected in the lighting system; therefore, the LCL ARR controller did not switch on the bar when he should have done so, probably due to an oversight.
The factors that may have contributed to this oversight will be examined below, together with an analysis of the actions of the north ground movement controller and those taken by ENAIRE after the incident.
Actions taken by the local arrivals controller
Several factors led to the controller having to manage a backlog of tasks simultaneously before the incident. One of these was the management of a non-preferential take-off. The procedure for a non-preferential runway take-off requires multiple steps to be followed and additional coordination by the local arrivals controller (LCL ARR) with the north ground movement (GMC N) and approach (APP) controllers.
In addition, two changes to the initial plan were made at short notice, as detailed below:
- The initial sequence had aircraft DAL169 taking off on runway 24R as the first traffic after the configuration change. The controller carried out the first steps of the nonpreferential take-off checklist correctly, advising the GMC N controller at 13:55:21.
However, due to the DAL169 aircraft taking slightly longer than expected, when it was finally ready, the controller judged the take-off slot to be insufficient. He therefore decided to look for a new slot, causing the first change of plan, due to the unfulfilled expectation that the aircraft would be ready on arrival at the holding point.
- The new plan was for DAL169 to take off after an ITA Airways aircraft had taken off and a medical transport aircraft (with callsign ADN16D) had crossed the runway. He also advised GMC N of this and turned off the S14 stop bar (at 14:01:37). However, the aircraft before the ITA aircraft left the runway through an exit that blocked the movement of aircraft ADN16D, which was then unable to get to the runway holding point in time.
- As a result, a second plan had to be made, with the LCL ARR controller clearing aircraft DAL169 for take-off before aircraft ADN16D crossed the runway. The controller stated that the slot for DAL169 to take off was tight, which may have placed him under pressure and played a role in the oversight.
In conclusion, the increase in simultaneous tasks resulting from the non-preferential takeoff, combined with two successive changes of plan, the last of which took place two minutes before the take-off was cleared, may explain why the controller had to concentrate on several different things in a brief period of time, and it was under these circumstances that the oversight occurred. That said, the workload was not excessive, and these types of changes in plan are not uncommon in the daily workload of a controller.
Non-preferential take-off checklist
Due to the multiple steps to be followed prior to a non-preferential take-off, there was a specific checklist for the procedure (shown in point 1.17.1).
The local arrivals controller started going through the checklist items correctly, following the initial plan. However, after the take-off of aircraft DAL169 was postponed, and then the runway crossing of ADN16D was delayed, the controller did not restart the checklist from the beginning (or skipped a few steps) because he failed to re-coordinate the take-off with the GMC N controller (second item on the checklist) and did not activate the stop bar (seventh item on the checklist) nor advise his colleagues.
After analysing the checklist, we have concluded that the text for each item is too long, and there are too many words highlighted in red, which makes it harder to follow than it needs to be, especially when the checklist takes a long time to complete or has to be restarted from the beginning. We feel that a more concise checklist would help controllers complete it more efficiently and make it less likely that they would skip items or neglect to restart it when necessary.
Following the incident, ENAIRE is undergoing a revision and update of the non-preferential runway take-off checklist to make it more concise and efficient.
Ergonomics of the SMP (Lighting Control and Indicating System)
As noted in point 1.17.1, the SMP is approximately one metre away from the controller's normal position, and its orientation prevents it from being seen unless the controller is in front of it. This means that to modify or check the status of the stop bars, the controller has to move from their principal position in front of the radar screens. Consequently, if the controller forgets to change the status of a stop bar, there would be no visible warning to alert them of the oversight whilst in their normal position.
Furthermore, because of the way the system works, once the process of changing the status of a bar is done, you have to double-click on a button on the SMP screen and wait a few seconds for a confirmation of the status change. It is entirely conceivable that a controller could double-click and return to their main position without waiting to check whether the change has been made correctly.
As more modern and efficient methods already exist in other airports, such as lighting control 'tablets' or the integration of SMP functions in the SMGCS screen, we feel that it would be advisable for Josep Tarradellas Barcelona-El Prat Airport to improve the ergonomics of its SMP. Therefore, a recommendation will be made in this regard.
Actions taken by the north ground movement controller
The north ground movement controller (GMC N) provided aircraft RYR18NN with full instructions to taxi from its parking stand to the boundary that divides his area of responsibility with that of the central ground movement controller (GMC C). While these instructions comply with established procedures, we have concluded that, in this case, the controller could have acted more appropriately for the following reasons:
a) The controller was aware that there was an impending take-off from a nonpreferential runway in the next few minutes. Therefore, it would have been wiser to taxi the aircraft to the S14 stop bar and, once near it, re-assess and decide whether to cross it via the bypass or hold.
b) The controller relied on his local arrivals colleague to advise him to stop the flow of traffic through the bypass and also to switch on the stop bar in time, disregarding and overlooking the potential for his colleague to make an error.
c) The controller failed to use the SMGCS radar efficiently by not checking the position of the aircraft that was about to take off, and it fell to the GMC C controller to alert him to what was happening.
In terms of the measures taken, as a result of being surprised by the undesirable circumstances, the controller chose to stop the aircraft when it had already passed the stop bar without informing the crew of the reasons for this decision. By the time the crew stopped the aircraft, it was sitting on the extension of the runway, which made the situation even worse. By contrast, had he instructed the crew to accelerate, or even if he hadn't communicated anything at all, the aircraft would have been clear of the runway extension when the DAL169 aircraft flew over it.
Assessment of the actions taken by ENAIRE
The air navigation service provider, ENAIRE, conducted an internal investigation into the event and, as a result, put forward three recommendations. The actions taken by ENAIRE to prevent similar incidents in the future are considered satisfactory. In particular, the revision of the checklists. By simplifying them and making them quicker to follow, controllers will be less likely to follow them incorrectly in the future.
Trajectories and relevant time points (Graphics: CIAIAC):
Related Flight:
FR9366,
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