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Wednesday, 9 March 2011

Airbus Updates No.112

Report: Air France A321 and TAP A320 at Geneva on Jul 1st 2008, loss of separation after go-around

By Simon Hradecky, created Wednesday, Mar 9th 2011 17:38Z, last updated Wednesday, Mar 9th 2011 17:38Z
A TAP Air Portugal Airbus A320-200, registration CS-TNG performing flight TP-945 from Geneva (Switzerland) to Lisbon (Portugal), was cleared for takeoff from Geneva's runway 23, the crew used English for communication with tower.

At the time of the takeoff clearance an Air France Airbus A321-100, registration F-GTAE performing flight AF-1242 from Paris Charles de Gaulle (France) to Geneva (Switzerland), was on ILS approach to runway 23 about 3nm from the runway threshold, the crew using French to talk to tower had been told by tower to expect a late landing clearance. When the Air France Airbus was 0.5nm from the runway threshold at a height of approximately 300 feet (altitude of approx. 1600 feet) the crew received a windshear alert and went around however not without losing some height initially. The separation between the two aircraft reduced to 300 feet vertically and 1.3nm laterally before the conflict was resolved.

Portugal's GPIAA released the
final report issued by Swiss BFU, the Swiss BFU website does not (yet) contain the report. The Swiss BFU concluded:
The serious incident is due to a critical convergence of an aircraft in go-around phase and an aircraft taking off, in consequence of an inadequate separation.

A contributing factor was a windshear alert which caused a go-around initiated nearby the threshold of the runway.

The BFU reported that all requirements for a reduced runway separation of 2400 meters laterally between the aircraft were fulfilled at the time of the occurrence and the tower controller was applying reduced runway separation.

The Air France Airbus A321 had reported on tower in French while 9nm out and had been instructed to report again at 2nm out.

When the A321 was 3nm out tower cleared the TAP A320 for takeoff, communication between tower and the TAP crew went in English.

When the A321 was about 0.5nm out the crew encountered a fairly severe windshear alert with an associated loss of airspeed at about 300 feet above ground (1600 feet MSL). The crew applied an emergency maneouver, applying full thrust and rotating the nose up, to arrest the resulting "discernable plunge", and reported going around. The tower instructed the A321 to climb to 7000 feet on runway heading and instructed the A320 to stop the climb at 5000 feet. At that time the departing A320 had not yet reached a point 2400 meters down the runway (reduced runway separation).

About 17 seconds later the A321 climbed through 2300 feet at an airspeed of 187 KIAS, trailing the TAP A320 which was climbing through 1800 feet at 178 KIAS about 1.4nm ahead of the A321. The Air France crew commented later in their air safety report that they had visual contact to the preceding A320 and rated the convergence of the aircraft "disturbing".

Following coordination between tower controller and approach control the tower then instructed the Air France A321 to turn left onto a heading of 180 degrees 47 seconds after the go-around.

The separation between the aircraft reduced to 300 feet vertical and 1.3nm lateral according to radar data before the conflict was resolved.

The TAP A320 reached Lisbon without further incident. The Air France A321 landed safely on their second equally turbulent approach, that however did not encounter a windshear.

The BFU reported, that there had been no indication or prediction of windshear prior to the go-around of the Air France A321, neither weather services nor pilots had reported any indication of windshear.

The BFU analysed that in case of a late go-around in conjunction with a takeoff from the same runway tower must re-establish separation of 1000 feet vertical or 3nm lateral. When applying reduced runway separation the tower has to implement an avoidance maneouver for the aircraft going around to ensure that separation between the two departing aircraft still exists according to required separation minima. Tower therefore has to assign a flight path which diverges the aircraft and keeps the aircraft clear of obstacles.

A right hand turn as stated in the missed approach procedures could not have assigned being prohibited between within 3nm from the Geneva VOR. The left hand turn as assigned was an appropriate solution, however, should have been accompanied by a climb rate limitation to the Air France A321. Both crews should have received traffic advisories by tower, who omitted such information in his transmissions.

The BFU further analysed that the form of the resolution of a conflict from a late go-around and a departure is left to the controller's discretion resulting in controller decisions that are both manifold and different, the instructions in terms of heading, speed and altitude being the result of decisions taken in an urgent situation.

Re-establishing separation standards following a late go-around near the runway threshold with a departure in progress while applying reduced runway separation criteria however may prove problematic because of the topographical environment in Geneva, that necessitates the rapid acquisition of minimum altitude under radar guidance.

The BFU therefore voices the opinion that a standard alternative go-around procedure should be established to de-conflict a late go-around and a departure, this procedure should be instructed and trained by tower controllers.

Weather information had not indicated any possibility of storms in the area of Geneva although isolated stable, non-moving storm cells were forecasted across Switzerland and France. At the time of the occurrence large and developing cloud were observed above Geneva, storm clouds however had disappeared. The BFU could not rule out however that a few isolated vortices of air caused by the formation of clouds over high ground moved towards the approach sector and caused perceptible windshear. Other than that the approach did not present any problems from a meteorological point of view.

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