Volotea B712 and HOP! CRJ7 at Strasbourg on Apr 12th 2019, near collision between go around and takeoff

Last Update: November 20, 2020 / 11:49:20 GMT/Zulu time

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Incident Facts

Date of incident
Apr 12, 2019

Classification
Incident

Flight number
V7-2506

Aircraft Registration
EI-EXB

Aircraft Type
Boeing 717-200

ICAO Type Designator
B712

A Volotea Boeing 717-200, registration EI-EXB performing flight V7-2506 from Montpellier to Strasbourg (France), was on final approach to Strasbourg's runway 05.

A HOP! Canadair CRJ-700, registration F-GRZG performing flight A5-3526 from Strasbourg to Marseille (France), was cleared for takeoff from runway 05.

When the Boeing 717 reached about 1.5nm before the runway threshold the crew initiated a go around due to the CRJ-700 still in the takeoff run. Subsequently both aicraft climbed out and lost separation.

The French BEA reported the separation reduced to 100 feet vertical at 0.4nm horizontal distance. The occurrence was rated a serious incident (category near collision) and is being investigated.

TCAS resolution advisories activated in both aircraft, the CRJ-700 was instructed to climb and the B712 to level off at about 2300 feet. After being clear of conflict the CRJ-700 continued to Marseille for a landing without further incident, the B712 positioned for another approach to runway 05 and landed safely.

On Nov 20th 2020 the BEA released their final report concluding the probable causes of the serious incident were:

The following factors may have contributed to the crew of the CRJ700 being issued with an immediate take-off clearance although the Boeing 717 was at 3 NM on final approach:

- The LOC controller’s wish to optimize the use of the runway, without any particular reason and without anticipating the risks in the event of something unexpected happening, meant that the prescribed separations between the arriving and departing aircraft were not complied with.

- At the time of the incident, the absence of means, practices or systematic procedures at Strasbourg Entzheim airport, such as the setting up of an approach fix for runway 05.

- The aircraft type not being mentioned by the LOC controller when giving the traffic information to the crew of the CRJ700 with a view to an immediate take-off. This meant that the crew did not have all the information to allow them to judge whether they could guarantee the immediate take-off conditions and did not share the same situational awareness with the controller and the crew of the Boeing 717.

The following factors may have contributed to the activation of the TCAS resolution advisory between the CRJ700 which was taking off and the Boeing 717 which was in a go-around:

- The LOC controller not anticipating and developing action plans in the event of a potential conflict following a low-level missed approach or a delay with the immediate take-off.

- The situational awareness between the LOC controller and the two crews not being shared.

- The initial paths for the departure and missed approach, to the NDB at 2,500 ft, not guaranteeing sufficient separation between the aircraft.

The BEA released following safety lessons:

One of the tasks of the airport controller is to “expedite and maintain an orderly flow of air traffic”. He may do this by approaching the regulatory minima when this is necessary, but this should not be done systematically due to the ensuing risk of exceeding them. Thus, the optimization of the use of the runway and the search for operational efficiency must not take precedence over the prevention of collisions which requires the controller to continuously carry out a strategic analysis of the risks.

After an in-flight incident, it is particularly complex for a captain to synthesize the useful information to explain it and continue the flight. The emotional load makes it difficult to be objective about the incident that has occurred, even if there are no more consequences for the rest of the flight, for both the flight crew and the cabin crew. Sharing information with the crew can, however, affect certain crew members according to their sensitivity and their experience.

The BEA summarized the sequence of events:

The crew of the Boeing 717, operating the Volotea flight from Montpellier Méditerranée (Hérault), were carrying out an ILS approach to runway 05 (QFU 047) at Strasbourg Entzheim airport. Exchanges between the controller and the crew were in English. At 13:01, the LOC controller asked the crew to continue the approach, indicating that they were number two behind a light aircraft on the downwind leg for runway 05. Four minutes later, the captain of the CRJ700 operating the HOP! flight bound for Marseille Provence (Bouches-du-Rhône), and PM, contacted the LOC controller, at the GND controller’s request, to advise that they were approaching holding point H and that they were ready for departure from runway 05. The exchanges between the controller and the CRJ700 crew were in French. At 13:05:14, the LOC controller asked them if they were ready to take off within the minute and gave them traffic information about an aircraft at 3 NM on final approach without specifying that it was a Boeing 717. The PM of the CRJ700 accepted and at 13:05:23, the LOC controller cleared them for an immediate take-off from runway 05 (point 1).

The Boeing 717 was around 3 NM from the runway threshold on final approach at an altitude of 1,650 ft(4) and an indicated airspeed of 136 kt when the CRJ700 was around 30 m before holding point H. At 13:05:46, the captain of the Boeing 717, PM, announced that they were at 2 NM on final approach. The crew of the CRJ700 lined up on runway 05. The LOC controller informed the crew of the Boeing 717 of the departure of the CRJ700 and asked them to continue the approach. The PM of the Boeing 717 said “unbelievable” on the frequency. Five seconds later, the crew of the CRJ700 started the take-off run (point 2).

At 0.90 NM from the threshold of runway 05, at an altitude of 890 ft and an indicated airspeed of 138 kt, the PM of the Boeing 717 informed the LOC controller that they may interrupt the approach. The LOC controller told the crew to continue the approach. Nine seconds later, at 13:06:28, at 0.58 NM from the threshold of runway 05 at a height of 240 ft (40 ft below the decision height (DH) ), the crew of the Boeing 717 initiated a missed approach and announced this on the frequency. The CRJ700 was still on the runway at 0.42 NM (780 m) from the threshold of runway 05 at a speed of around 115 kt (point 3).

The LOC controller asked the PM of the Boeing 717, who read this back, to keep straight ahead during the missed approach. The PF selected heading 042° and the Boeing 717 started to deviate to the left of the runway centreline. When the HOP! CRJ700 flew over threshold 23 at an altitude of 900 ft and a speed of 160 kt, the separation with the Boeing 717, whose speed was 163 kt and accelerating, was around 1 NM horizontally and 920 ft vertically (point 4).

The LOC controller asked (point 5) the crew of CRJ700, at an altitude of 1,300 ft and climbing to 6,000 ft to directly turn left towards MIRGU, the last standard instrument departure point (SID)(5), and the crew of the Boeing 717, at an altitude of 2,300 ft and climbing to 2,500 ft, to immediately turn right to heading 050° (point 6). The CRJ700 started turning at 2,100 ft. The horizontal and vertical separations between the aeroplanes were respectively 0.6 NM and 300 ft. The speed of the Boeing 717 was 60 kt higher than that of the CRJ700. The LOC controller asked the crew of the CRJ700 to stop climbing at 2,000 ft. The PM of the CRJ700 asked him to repeat the instruction. The CRJ700 flew through 2,400 ft and was climbing with a vertical speed of around 1,300 ft/min and the Boeing 717 was stable at 2,500 ft. At the same time, the TCAS of the two aeroplanes transmitted traffic advisories (TA). The LOC controller replied to the PM of the CRJ700 by telling him to immediately stop climbing at 2,000 ft. A second later, resolution advisories (RA) were generated on board each plane: MAINTAIN CLIMB for the CRJ700 and DESCENT for the Boeing 717 (points 7). The horizontal and vertical separations between the two aeroplanes were respectively 0.40 NM and 50 ft. The resolution advisory (RA) of the CRJ700 was reinforced to INCREASE CLIMB and the PF increased the rate of climb. Five seconds later, the separations were 0.28 NM and 95 ft. The minimum horizontal distance between the two aeroplanes of 0.17 NM was reached five seconds later with a vertical separation of 500 ft.

At 13:07:55, the path conflict had ended and the two crews continued their flights (point 8).

The BEA analysed with respect to the use of English:

The use of just English might have meant that the crew of the Boeing 717 were aware of the character of the instructions given in French to the crew of the CRJ700, and allowed them to adapt their path accordingly and thus avoid the activation of the TCAS resolution advisories.

However, it is not possible to determine if the monitoring of the few exchanges which followed the take-off clearance, made by the crew of the CRJ700 during the take-off run, would have resulted in better situational awareness if only English had been used.

The BEA analysed with respect to the crews:

Crew of Boeing 717-200

The crew specified that it was the fourth and last rotation of the day and that they were running around one hour late due to a technical problem which had occurred between the second and third rotation.

The captain, of Spanish nationality, and the first officer, of French nationality, indicated that they heard the clearance to take-off given to the crew of the CRJ700 when the aeroplane had not yet arrived at the holding point. They were at around 3 NM from the threshold of runway 05. They found the CRJ700 a bit slow in lining up. At this point, they knew they would have to execute a missed approach taking into account a potential conflict in the initial climb. The weather conditions did not provide any difficulty. The captain was irritated by the way the situation was being managed as there were only two aeroplanes in the circuit. On approaching the DH, when the controller told them to “Continue” and the CRJ700 was still on the first third of the runway, the crew initially started a missed approach in manual control. The reason behind the selection of heading 042°, different from the runway magnetic heading, could not be explained.

The crew were expecting to turn right in order to avoid a conflict with the departing CRJ700 (which should turn left according to the standard departure procedure) but the controller asked them to keep straight ahead. They had to climb to an altitude of 2,500 ft. The first officer remained concentrated on the management of the path. The captain did not understand the controller’s instructions given in French to the crew of the CRJ700 who were of French nationality. He was surprised that, in a potential conflict situation, the exchanges were not carried out in a shared language, in English only. Neither of the two crew members had visual contact with the CRJ700.

The first officer disconnected the autopilot in order to follow the TCAS resolution advisories. The pilots said that the orders were consistent with what they had already practised in simulation sessions. Nevertheless, the situation was dangerous and they had been afraid. They saw the CRJ700 pass in front of them in a left-hand climbing turn.

Crew of CRJ700

The crew indicated that they were concentrated on the actions and technical calls with a view to lining up and carrying out a rolling take-off. Even though there had been a lot of exchanges in English between the LOC controller and the crew of the Boeing 717, they were not aware that it was on final approach. They thought that the traffic mentioned by the controller, when they were asked whether they were ready to depart within the minute, was a local flight or a runway circuit under VFR.

While climbing through 2,450 ft, the controller asked the crew to maintain 2,000 ft and the crew made a slight nose-down input. At the same time, the TCAS was activated, transmitting a MAINTAIN CLIMB and then INCREASE CLIMB resolution advisory. The indication on the aeroplane’s vertical speed indicator required a high vertical climb speed (fully up), the dial of the vertical speed indicator being mainly red. The pilots were very surprised to have to take such a pitch attitude for the climb. They had been afraid and had expected to strike an aircraft. At this point, the crew were not aware that the Boeing 717 had executed a missed approach. The pilots specified that they had never had visual contact with the Boeing.

Shortly after the incident and not realising how it might affect the cabin crew, the flight crew explained to the cabin crew who had entered the cockpit, what had happened during the take-off.

Incapacitation of a cabin crew member of the CRJ700

The HOP! flight cabin crew were composed of a purser and another cabin crew member. They both perceived the abnormal situation shortly after take-off. The purser indicated that the other cabin crew member had joined him at the front of the aeroplane and that when the cockpit door was opened shortly after the incident, he saw that the faces of the two pilots were frozen. They had just requested an explanation from the approach controller. The captain then told them what had happened during the take-off and initial climb. The cabin crew member then recalled a serious incident which had occurred several years earlier when he had been a cabin crew member for another operator. The recollection of this memory greatly upset him. The purser noticed this, and informed the captain that the cabin crew member would no longer be able to carry out his tasks on both the flight underway and on the next flight (which as a consequence, gave rise to a limitation to 50 passengers).

Regulations require that there is a complement of a minimum of one cabin crew for every 50 passengers. With 73 passengers on board, and one cabin crew member incapacitated, cabin safety might have been impeded.

The BEA analysed the testimony of the tower controller:

LOC controller experience and statement

The LOC controller holds an air traffic controller licence with aerodrome control instrument (aerodrome radar control and tower control) and approach control surveillance ratings. He is also a simulator and position instructor. Before joining Strasbourg Entzheim in 2012 where he was qualified in 2013, he was first qualified as controller at Bâle Mulhouse airport in 2001.

The day of the incident he had started his shift in the LOC position at 12:30. He indicated that there must have been one or two VFR aircraft to be managed before the arrival of the CR700 and Boeing 717 crew on the frequency. He added that when the crew of the CRJ700 contacted him ready for departure on the LOC frequency, the CRJ700 was, according to him, nearly at holding point H and the Boeing 717 was stabilized on final approach to 05 at around 3.5 NM from the runway threshold. The LOC controller did not think that proposing an immediate take-off would give rise to any particular problem. The LOC controller considered that based on the decided tone of voice of the crew member of the CRJ700, the latter had clearly understood the constraint and that he shared the same understanding of the situation. The LOC controller considered that the CRJ700 had not lined up as quickly as hoped.

When the CRJ700 left the ground, the LOC controller considered that the Boeing 717 could land. He waited before giving the clearance to land to check the spacing. He confirmed that he would have been required to clear the crew of the Boeing 717 to land before the CRJ700 had crossed the end of the runway. He was surprised by the decision of the Boeing 717 crew to execute a missed approach. He added that in his opinion it was more dangerous to execute a missed approach behind the departing aeroplane than to land a bit too close behind it.

The LOC controller indicated that he did not wish to disturb the crew of the Boeing 717 during the execution of the missed approach. He thus asked them to keep straight ahead and asked the crew of the CRJ700 to turn towards the last SID point to ensure the separation. He added that he was convinced at this point that the crew of the CRJ700 were perfectly aware of the situation as they had been cleared for an immediate departure and had had the position information about the traffic in final approach. The LOC controller indicated that he had waited to have radar contact with the CRJ700 as visually, with the parallax, it was not easy for him to know its position. The radar blip appeared at around 1,600 ft and the LOC controller explained that it seemed to take a long time for it to appear. He added that when the CRJ700 appeared on the radar screen, his “heart jumped”: the Boeing 717 had deviated to the left of the runway centreline and not the CRJ700. The LOC controller thus saw that his instructions had not had the desired effect. This was an emergency situation for the LOC controller, which was not improving as there was a contradiction with the instructions he had given. The LOC controller considered that the crew of the CRJ700 were not at all on alert as they asked him to repeat the message to stop climbing. He then repeated the altitude limitation, this time using the emergency phraseology.

The LOC controller heard the crew of the Boeing 717 express their discontent on the frequency in this lapse of time and he considered that this contributed to increasing his emotional load. He asked the Boeing 717 crew to turn to heading 050° but he realised that this heading would not change anything as it was that of the runway centreline. During the TCAS resolution, he took no action, which is normal procedure and left the crews to manage the situation. He then transferred the two aeroplanes to the approach frequency.

The LOC controller indicated furthermore that:

- He had probably built up confidence from the day before when he had managed a lot of VFR traffic with the Aero 2019 general aviation air show at Friedrichshafen. He thought that this could have influenced his decision.

- He thought that the two crews were fully aware of the situation and that they had the same situational awareness as him.

- He thought that he was ready to manage this type of situation (due to, in particular, feedback and discussions with his colleagues) but ultimately, he realised that this was not the case and that he had little time to detect, analyse and decide in such a situation.

- He had the impression that seconds were lost because he could not see the radar blip of the CRJ700 on his screen which would not have been the case at Bâle-Mulhouse where he had worked.

- The rhythm at Bâle-Mulhouse where he had worked previously was higher than at Strasbourg Entzheim.

The BEA reported Eurocontrol had conducted a study in low height go arounds (from below 400 feet AGL) and found that only 8 of 187 occurrences resulted in conflicts. Of these 8 occurrences only "providence" prevented a midair collision in two occurrences. Eurocontrol identified 6 scenarios which could lead to a low height go around and listed measures for:

- prevent conflicts before or after low height go arounds
- mitigate the collision risk after low height go around
Incident Facts

Date of incident
Apr 12, 2019

Classification
Incident

Flight number
V7-2506

Aircraft Registration
EI-EXB

Aircraft Type
Boeing 717-200

ICAO Type Designator
B712

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