Vueling A320 and RAM B738 at Barcelona on Jul 6th 2018, near collision

Last Update: June 4, 2019 / 20:42:26 GMT/Zulu time

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Incident Facts

Date of incident
Jul 6, 2018

Classification
Incident

Airline
Vueling

Flight number
VY-6101

Destination
Barcelona, Spain

Aircraft Registration
EC-HQL

Aircraft Type
Airbus A320

ICAO Type Designator
A320

A Vueling Airbus A320-200, registration EC-HQL performing flight VY-6101 from Rome Fiumicino (Italy) to Barcelona,SP (Spain) with 178 passengers and 6 crew, was on approach to Barcelona's runway 07L descending through about 4000 feet.

A RAM Royal Air Maroc Boeing 737-800, registration CN-RNU performing flight AT-964 from Casablanca (Morocco) to Barcelona,SP (Spain) with 118 passengers and 6 crew, was on approach to Barcelona's runway 07L descending through about 4000 feet at the same time.

Spain's CIAIAC reported the separation between the aircraft reduced to 200 feet vertical and 1.1 nm horizontally. The conflict was resolved and both aircraft continued for safe landings. The occurrence is being investigated by the CIAIAC.

On Jun 4th 2019 the CIAIAC released their final report concluding the probable cause of the incident was:

The investigation has determined that this incident was caused because the controller was not aware of all the traffic in his area of responsibility (that is, sector LEBLT3E) and that were of concern, even if they were no longer on his frequency.

The CIAIAC analysed:

The Airbus A-320-214 operated by Vueling Airlines had been cleared by the sector LEBLT3E controller to proceed to waypoint BL542 in order to transition, at an altitude of 4000 ft, to the final approach for the Barcelona Airport.

At 12:26:17, as the aircraft was proceeding to waypoint BL542 from holding pattern VIBIM, the controller instructed its crew to contact the Final controller. The aircraft was still in his sector (LEBLT3E).

The aircraft’s ground speed was 220 kt according to the radar track. The chart for transitioning to the final approach specifies a maximum speed (IAS) of 220 kt at RNAV RUBOT1E leg. The wind speed at that altitude is not known, so the compliance with said speed restriction cannot be evaluated; however, the aircraft’s ground speed during the incident remained constant.

At the same time, the Boeing 737-800 operated by Royal Air Maroc had been cleared by the sector LEBLT3E controller to proceed to waypoint BL546 to transition to the final approach for the Barcelona Airport at an altitude of 5000 ft. However, this aircraft did remain in contact with the sector LEBLT3E controller as the executive controller in sector LEBLT3E was being relieved.

ENAIRE, in its Operations Manual for the station, provides a protocol or checklist so that when controllers are relieved, the oncoming controller receives all of the necessary information. The controllers involved in this incident received training in this regard and are aware of this protocol. Both stated that the turnover was, in their opinion, conducted correctly and that all of the necessary information was relayed to the oncoming controller.

During turnovers, the oncoming controller should be made aware of the general situation in the sector, which particular emphasis on those aircraft that are or could cause conflicts, whether or not they are on the frequency. In an approach sequence or pre-sequence (as in this incident), the first traffic in the sequence is transferred to the next sector when it is “clear of conflicts”; that is, when the traffic has no other aircraft ahead of it and will not pose a conflict to the other traffic remaining in the sector and on the frequency. However, this action does not necessarily entail that the next traffic in the sequence (#2) is “clear of conflicts”, since the position of the #1 traffic could affect it. Therefore, the #1 traffic, even if on another frequency, could be essential traffic for the #2 traffic, and therefore priority information to relay during a turnover.

The workload during the turnover between the controllers was not high; in fact, the oncoming executive controller defined the situation as simple.

Therefore, neither the operational situation at the time of the turnover, nor the fact that no mention was made during said turnover of the presence of a traffic that was still in the sector but that was no longer on the frequency, justifies the oncoming controller’s failure to notice that the traffic could be of concern. After the turnover, the sector LEBLT3E controller contacted the Boeing 737-800 to clear it to descend to 4000 ft.

During the incident, the aircraft’s ground speed exceeded 220 kt according to the radar track. The wind speed at that altitude is not known, so the compliance with the speed restriction specified in the chart to transition to final approach cannot be evaluated; however, at no point did the sector LEBLT3E controller instruct the aircraft to reduce its speed.

Subsequently, at 12:29, separation between the two aircraft was lost. Seconds earlier, the Royal Air Maroc aircraft was flying in a volume where the PAC (conflict caution alert) and VAC (conflict violation alert) of the SCTA system are inhibited to avoid numerous nuisance alerts, which is why the PAC alert was not received at any point. However, the VAC alert was activated on the display of the sector LEBLT3E controller, since the incident occurred just beyond the alert inhibition volume.

According to his statement, at no time was the controller cognizant of this alert or of the loss of separation.

The crew of the Royal Air Maroc aircraft did notice this loss of separation, as they were in visual contact, and they informed the sector LEBLT3E controller that they had another aircraft ahead of them within 2 NM and at the same altitude, and they requested leaving the approach to the left.

The executive controller was not aware of the presence of traffic in his sector that could affect the others. Two reasons might explain this:

- First, the outgoing executive controller had already transferred that traffic to another frequency. When a traffic is transferred to another sector, it changes color on the display of the sector’s air controller, and is shown in blue (this color denotes traffic of interest, such as the Vueling Airlines aircraft) instead of dark green (this color shows accepted traffic, that is, those whose communications have been accepted, as in the case of the Royal Air Maroc aircraft). This distinction could have caused cognitive attention bias in the controller, meaning he gave preference to information that affected him directly (namely, the traffic in his frequency) while ignoring collateral information (that is, the traffic in his sector that had been transferred to another).

- Another possible reason for this inattention by the air traffic controller is that his focus was away from the area where the loss of separation took place, since at that very moment he was communicating with two other aircraft that were in the VIBIM holding pattern.
Incident Facts

Date of incident
Jul 6, 2018

Classification
Incident

Airline
Vueling

Flight number
VY-6101

Destination
Barcelona, Spain

Aircraft Registration
EC-HQL

Aircraft Type
Airbus A320

ICAO Type Designator
A320

This article is published under license from Avherald.com. © of text by Avherald.com.
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