On 19 October 2012 a Fokker F100 aircraft (F100), registered VH-NQE, was being operated on a passenger charter flight from Perth Airport to Nifty Aerodrome in the Pilbara region of Western Australia. The weather for the approach into Nifty included high-based cumulus cloud and isolated thunderstorms. The temperature on the ground was 38 °C.
As the flight crew were positioning the aircraft for a 5 NM (9 km) straight-in approach into a slight headwind, they received a windshear caution. In response, the crew increased the approach speed and extended the speed brake to stabilise the approach.
The approach continued and apart from a few minor speed variances, the conditions appeared relatively benign. As the aircraft was in the final stages of the approach and descending from 80 ft to 30 ft above ground level, the airspeed dropped from 133 kt to 110 kt and the rate of descent increased to about 1,000 ft/min. The loss of airspeed occurred over a period of 3 seconds and by touchdown the aircraft was being affected by a 32 kt tailwind.
The aircraft touched down on the runway threshold, almost 300 m short of the normal touchdown point, and bounced. The high rate of descent at initial touchdown resulted in a hard landing with significant aircraft damage. There were no reported injuries to passengers or crew.
What the ATSB found
The ATSB found that when the aircraft was on approach to land at about 80 ft above ground level, the flight path almost certainly coincided with the strong outflow of a dry microburst, resulting in a performance-decreasing windshear that led to the rapid drop in airspeed, high sink rate, undershoot and a hard landing. Also, the aircraft was not fully configured for an approach in known or suspected windshear conditions, reducing the capability of the aircraft to recover from the high sink rate associated with a microburst event.
What's been done as a result
As a result of this occurrence, the operator sought to improve the weather information available at aerodromes serviced by their F100 fleet and modified its simulator training program along with consolidation of the windshear procedures/guidance. The operator also provided additional guidance in the use of flap following receipt of a windshear caution during approach and planned to introduce a new threat-based take-off and landing briefing model.
The circumstances of this occurrence show that operators of transport category aircraft may need to review the guidance provided to crews to ensure that the risk of windshear associated with both thunderstorms and dry microbursts, is effectively managed.