Swiss A333 and RJ1H at Zurich on Mar 22nd 2013, loss of separation
Last Update: April 8, 2015 / 20:57:53 GMT/Zulu time
Incident Facts
Date of incident
Mar 22, 2013
Classification
Incident
Airline
Swiss
Flight number
LX-18
Departure
Zurich, Switzerland
Destination
Newark, United States
Aircraft Registration
HB-JHD
Aircraft Type
Airbus A330-300
ICAO Type Designator
A333
A Swiss Avro RJ-100, registration HB-IYU performing flight LX-1192 from Zurich (Switzerland) to Nuremberg (Germany), was climbing through FL050 out of Zurich's runway 28 via DEGES2W departure route and was in contact with Zurich's departure control.
While climbing through FL050 and after turning east the Avro RJ-100 was flying in opposite direction to the A330 climbing at a higher rate of climb than the A330 and climbing through the altitude of the A330, according to radar data the lateral separation reduced to less than 1.5nm at 500 feet vertical separation while 30 seconds earlier the aircraft were already on opposite headings at 6.6nm distance at same altitude.
Switzerland's Accident Investigation Board SAIB reported the occurrence was a "close encounter" between the two aircraft, an investigation into the airprox has been opened.
On Apr 8th 2015 Switzerland's SUST (Switzerland's Accident Investigation Board) released their final report in German reporting the separation between the two aircraft reduced to 350 feet vertically and 1.8nm horizontally respective 525 feet vertically and 1.5nm horiztonally and concluding the probable cause of the loss of separation was:
the serious incident happened when the responsible air traffic controller, on the job training controller, intervened too late when the trainee controller did not recognize early enough that two aircraft were on conflicting trajectories.
A systemic factor was identified in various standard departure routes that inevitably cause conflicts between aircraft in unfavourable departure sequence, if air traffic control does not step in.
Contributing factors were:
- non-active support of the trainee by the trainer
- insufficient oversight of situation by the trainee
- the trainee was put under additional workload with a photo flight southwest of the aerodrome
- the time intervals of departing aircraft prior to the occurrence were not adequate for the situation
The following factor was recognized not as contributing to the occurrence however as a risk:
- the trainer issued a vector to turn to one crew immediately after the crew reported a TCAS resolution and before the crew reported clear of conflict
SUST reported that at the control desk an air traffic controller in training, supervised by an air traffic control instructor, was in charge of air traffic control. In the prior briefing it had been decided that the trainee would work entirely on her own while the instructor would provide input only where absolutely necessary. A first hour of work concluded without occurrence, the trainee and instructor went into a pause, following the pause the instructor took over to permit the trainee a full length of the pause. A photo flight was taking attention, the trainer requested longer intervals between the aircraft and described the traffic as increasing with workload increasing from medium to heavy, complexity medium. When the trainee returned to the console, she described the workload as low to medium, traffic volume high, complexity high. About 30 minutes after taking the position following the pause the serious incident occurred.
The trainee reported that she assessed the situation became too complex for her and she pressed the "wait" button indicating to tower to not release departures. LX-1192 however had already received takeoff clearance and was already accelerating when the wait button occurred, the takeoff clearance was not cancelled according to usual routine. Tower informed the trainee that the aircraft was departing and suggested to issue an altitude limit at 4000 feet, the trainee denied as the preceeding departure had already been constrained to 4000 feet.
LX-18 had been instructed to line up runway 16 and was already in position waiting for takeoff clearance for 5 minutes at that time.
The trainee released the wait signal about one minute after activating the button, LX-18 was instantly cleared for takeoff.
In the meantime LX-1192 had reported on departure climbing through 2800 feet and was issued to stop climb at 4000 feet.
After LX-18 became airborne tower issued an altitude constraint for LX-18 to stop climb at 4000 feet, he believed to have heard that LX-1192 had been cleared to 5000 feet and direct to waypoint KOLUL (as a matter of fact, this clearance had been issued to the aircraft before LX-1192) and therefore decided to limit the climb of LX-18 to 4000 feet insisting his assistant to coordinate the constraint with departure. SUST reported that no such coordination occured.
The trainee wanted to avoid a conflict with the departing traffic on runway 16 when she cleared the preceding departure before LX-1192 to climb to 5000 feet and fly direct to KOLUL. A short time later LX-18 reported on her frequency climbing to 4000 feet which surprised her as this had not been coordinated with her. She cleared LX-18 to climb to FL120 to ensure LX-18 would climb over the photo flight at 6000 feet in the south west of her control zone.
The trainer briefly discussed the situation with the trainee, she subsequently cleared LX-1192 to climb to 5000 feet and cleared the preceding departure to climb to FL120.
A short term conflict alert activated at the control desk indicating LX-1192 and a VFR aircraft were about to come into conflict. The trainer commented this would be a brief alert only and it was cleared that there would be no conflict arising. The photo flight reported their mission was finished and they were ready to climb or descend as needed and requested to turn right to Donaueschingen, the trainee cleared the flight to Donaueschingen maintaining 6000 feet.
Another short term conflict alert activated between LX-1192 and the photo flight, however, LX-1192 was climbing to 5000 feet only.
The trainer asked whether it was a good idea to have the photo flight fly direct Denaueschingen, the trainee discovered that a conflict was developing between the photo flight and LX-18 and issued a radar vector to the photo flight for traffic.
LX-1192 was cleared to climb to FL120. The trainer queried whether the separation between photo flight and LX-18 was sufficient, the trainee issued a radar vector to LX-18 as result, the transmission was blocked two times until LX-18 correctly read back the instruction. The trainee did not notice that LX-1192 was still tracking the standard instrument departure route, she believed she had cleared the flight to FL120 and direct to KOLUL.
Another short term conflict activated indicating a developing conflict between LX-1192 and LX-18. The trainer radioed directly instructing LX-1192 to turn right immediately to 100 degrees. A traffic advisory activated in the cockpit of LX-1192, 4 seconds later a resolution advisory "Climb! Climb!" activated, the crew disengaged the autopilot and while climbing through 5585 feet increased the climb rate. At the same time LX-18 at 5462 feet received a resolution advisory to "Descend! Descend!", the crew immediately initated a descent, the captain of LX-18 (pilot monitoring) established visual contact and informed ATC that they were following a TCAS resolution, the trainer issued the instruction to turn right to avoid the RJ. After LX-18 reported clear of conflict the trainer issued the clearance to LX-18 to climb to FL120.
Following the conflict the trainer asked the trainee whether she would feel ready to resume control, which she agreed with, and she began to issue instructions again.
The ATC supervisor phoned in however advising that he did not agree with the trainee continuing to work. Trainee and Trainer were relieved some time later.
SUST reported that the trainee had been declared to have a "training problem" indicating that her progress was not matching expectations and there was rather a decline in performance. In particular deficiencies in situation awareness had been observed. The declaration "training problem" is a tool to interrupt normal training and define objectives to be met usually within a period of 3-5 weeks. Once the objectives are met the trainee returns to normal training or otherwise enters a conditional go-status. The training problem was cancelled in July 2012. Following an absence in Jan and Feb 2013 due to sickness her performance was variable and on Mar 12th another "training problem" was declared with the objectives that planning needed to occur even in increased traffic volume and complexity in time and on her own. It had been observed, that while she delivered excellent performance up to medium traffic volume she did not continue planning when traffic volume increased and only resumed planning on intervention by the trainer.
SUST reported that the trainee provided testimony following the occurrence that she believed LX-1192 had already turned direct to KOLUL. Later she observed the aircraft turning towards Kloten VOR and realised the aircraft was still on the standard departure route just a few seconds before the trainer radioed LX-18 directly and took control.
The SUST analysed that the trainee was under special pressure due to her "training problem" status. Nonetheless, she acted according to the situation, including reducing the pressure by pressing the wait button, until the trainer asked whether she would find it a good idea to have the photo flight fly direct to Donaueschingen.
The SUST condemned this way of interaction as inappropriate causing only feelings of uncertainty with the trainee in her special pressure and the knowledge that she could not afford any mistake due to her status. The trainee concluded from the question however that her handling of the photo flight was not deemed appropriate and consequently focussed on the separation of the photo flight with other traffic.
When LX-1192 and LX-18 came into conflict the trainer reacted at the same time as the short term collision alert activated, the reaction was correct but too late. The responsibility for the traffic is still with the trainer, the SUST annotated. The instruct to turn right after the report of a TCAS resolution conflict was in conflict with ICAO documentation instructing air traffic controllers to not change the course of aircraft in a traffic resolution advisory until after the crews reported clear of conflict.
The SUST analysed highly critical that the trainer permitted the trainee to continue work following the occurrence, which the SUST rated a loss of control over the overall situation and a serious incident other than both trainer and trainee rated the occurrence. The supervisor correctly rated the occurrence a serious incident and required the relief of both controllers.
SUST reported that the training of the trainee was aborted on Mar 28th 2013.
Aircraft Registration Data
Incident Facts
Date of incident
Mar 22, 2013
Classification
Incident
Airline
Swiss
Flight number
LX-18
Departure
Zurich, Switzerland
Destination
Newark, United States
Aircraft Registration
HB-JHD
Aircraft Type
Airbus A330-300
ICAO Type Designator
A333
This article is published under license from Avherald.com. © of text by Avherald.com.
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