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Mode Aviation
Reference No. AR201500088
Date reported 28 October 2015
Concern title The use of independent visual approaches (IVAs) when windshear alerts are present
Concern summary

The concern related to the use by controllers of IVAs to separate aircraft on approach to Sydney when there are windshear conditions present.

Industry / Operation affected Aviation: Air transport
Concern subject type Aviation: Flight crew

Reporter's concern

The reporter expressed a safety concern regarding the inappropriate use of IVAs on approach to Sydney Airport when windshear alerts are present.

The reporter advised that they had been approved for an arrival via BOREE for runway 16L at Sydney, which was subsequently changed to the CALGA ONE arrival runway 16L. IVA approaches were being conducted and there was windshear forecast.

Approaching LANOL at approximately 25 NM from Sydney, air traffic control (ATC) requested that the crew report visual with runway 16 L as soon as possible. The crew were unable to get visual contact with the runway and in the absence of any further instructions from ATC, they requested a vector to intercept the localiser to ensure sufficient track miles for their approach. ATC assigned a heading for an intercept and revised the descent clearance from 3,000 ft to 4,000 ft. While on a heading intercept for the localiser they were able to report visual. They were then given a descent to not below 2,200 ft until established on the glidepath.

As a result of the increased workload, late intercept of final, weather conditions, requirement to be looking outside for visual contact and the windshear conditions, a flap overspeed occurred.

The flap overspeed caused extra workload in an already challenging situation caused by the weather conditions and ATC traffic management.

The reporter comment: I am concerned that an IVA is not appropriate when windshear alerts are issued. Vectoring for a final intercept of 15 NM or greater should have been the order of the day. I am concerned that increasingly, ATC have an obsession to expedite traffic movement ahead of safety and that there are no overriding guidelines as to when the IVA is not appropriate.

Operator's response (Operator 1)

Airservices Australia (Airservices) clarifies that IVAs will not be used if there is likelihood of pilots being unable to comply with the parameters of the procedure. While IVAs support efficient use of airport capacity, safety of the procedure takes precedence. Forecast windshear, although a consideration, does not, in itself, make an IVA an unsuitable approach.

Airservices maintains an ongoing focus on promoting pilot awareness of the importance of communications with ATC. For example, at a go-around working group workshop conducted by Airservices with airlines earlier this year, the importance of effective communication between aircrew and ATC of unsuitable instructions that may potentially place the aircraft in an unstable approach was discussed.

In respect of the reported event, Airservices clarifies that the aircrew can advise ATC of their preference to continue to track on the assigned heading to intercept the localiser after reporting visual.

Taking into consideration the lessons learned from this reported concern, Airservices will continue to emphasise the importance of pilot advice to ATC of instructions that may place the aircraft in an undesirable state in ongoing safety promotion activities.

Regulator's response (Regulator 1)

CASA has reviewed the REPCON and notes and supports the response from Airservices. CASA will consider this information in the context of ongoing surveillance of Sydney air traffic control.

Further response from reporter

In response to the REPCON report the reporter provided the following comments:

Sadly but not surprisingly, I think Airservices have missed the point completely.

First, let me clarify that there were multiple go-arounds occurring at Sydney just prior to our arrival. Significant is that we were instructed to hold 70nm North of TESAT and it was explained this was due to the number of go-arounds.

It was clear that the prevailing windshear conditions were actual conditions. The statement that forecast windshear does not make an IVA unsuitable as an approach is irrelevant as forecast conditions had become actual. Similarly forecast fog does not preclude an IVA approach unless it becomes actual.

Airservices made the statement ‘Airservices clarifies that aircrew can advise ATC their preference to continue to track on the assigned heading to intercept the localiser after reporting visual’. This statement bears no relevance to the event and would not have prevented the flap overspeed. When we were left tracking to LALOL we requested a vector for the localiser as it was obvious that if we did not do so at that time, it would have made the intercept of final even more difficult in terms of vertical profile. In all circumstances, once we are established on an intercept heading for final and, provided the localiser is identified, we will always intercept the localiser, so informing ATC of this process does not alter the actual flight path that the aircraft follows and has no bearing on the IVA at all.

In addition to my initial report, I need to emphasise that ATC 'sounded' stressed and obviously 'under the pump' with managing the situation and the frequency was very congested. We were always going to be able to manoeuvre to the centreline, but in this case, ATC were relying on us to sight the runway at night with an uneven and scattered cloud base. I believe ATC needed to provide the initiative for the heading intercept for the localiser with a request for us to report when visual.

In times of turbulence and windshear, we require close monitoring of our airspeed in order to avoid flap overspeeds. Being required to look outside in these conditions is not appropriate and distracted us from vital speed trend monitoring at a critical time.

Finally, to sum up in this case, the only ATC instruction that may have placed the aircraft in an undesirable state was the request to report the runway in sight. In the absence of our confirmation of runway in sight, it is up to ATC to come up with an alternate plan. There was a lack of awareness regarding the difficulty involved to sight the runway threshold in the conditions at the time and lack of an alternate plan from ATC when the runway could not be sighted.

If I had my time over again, I would have continued to fly over the top of the field which would only have created a higher workload for ATC, but in this case, I believe we would have avoided the flap overspeed.

Further response from Airservices

Airservices would like to offer the pilot an opportunity to visit the Sydney Terminal Control Unit (TCU) for a discussion regarding IVA procedures. The visit will enable Airservices to clarify any outstanding concerns from the reporter and assist the ATC's understanding of the practical use of IVA's through a pilot's perspective. In addition, the radar replay could be shown to the pilot if Airservices is provided with the date and call sign of the reported event.

The Air Traffic Flow Management (ATFM) processes have continued to be enhanced, supported by collaborative decision making. These changes provide increased options for the ATC system to respond to short notice interruptions to normal traffic, such as wind shear events affecting airport throughput.

The Sydney ATM Strategic Planning Group (SSAPG) is a collaborative initiative involving Airservices and industry representatives. SSAPG specifically deals with safety and efficiency issues associated with ATFM at Sydney Airport. A copy of the initial REPCON and subsequent comments by the pilot will be placed on the SSAPG agenda for discussion at the next meeting scheduled early in 2016.

ATSB comment

REPCON liaised with the reporter and arranged from them to attend the TCU for discussions. We have been informed that these were very productive discussions with lessons learnt on both sides.

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Last update 20 September 2016