Wednesday, March 28, 2012

Report says flight paths crossed

Flight paths of the aircraft over Queenstown in June 2010.

A Qantas aircraft was forced to climb at maximum speed to maintain separation from a Pacific Blue aircraft over Queenstown when their flight paths crossed. 

The "loss of separation'' incident sparked a Transport Accident Investigation Commission inquiry almost two years ago. 

The commission report, published today, says a Pacific Blue Boeing 737 was en route from Auckland to Queenstown on June 20, 2010. 

It was flown using instruments but pilots must be able to see the runway until landing. If they lose sight of the runway they must abort the landing and execute a figure eight "missed approach procedure.'' 

Pilots must circle while descending over Queenstown because terrain is mountainous, which means radar cannot be used. 

The Pacific Blue flight, with 82 passengers, arrived at the descent altitude, and while pilots spotted cloud the runway was clear. 

However, cloud patches were likely to obstruct a final approach so the pilots reported a landing on an alternative runway. 

Meanwhile, an air traffic controller cleared a Qantas aircraft en route from Sydney with 156 passengers to start an approach behind the Pacific Blue aircraft. 

A controller cleared Qantas for the approach based on an expectation that Pacific Blue, having started circling, would land or execute a figure eight. 

However, the Pacific Blue flight stopped circling and climbed to intercept the required heading for a missed approach. 

"They had not planned to enter or remain in the visual circuit as the controller had expected and, because of their position when they started the climb, probably could not have done so because of their proximity to terrain,'' the report says. 

A controller then told the Qantas pilot to conduct a missed approach procedure at a maximum rate of climb to maintain separation from Pacific Blue flight. 

Investigators did not establish whether the required 1000 feet vertical separation was breached because it was clear the potential for a breach was high and safety was an issue. 

The report found the weather was unsuitable for Pacific Blue to descend below a minimum descent altitude; a controller failed to ensure separation was maintained; Pacific Blue and air traffic control had different understandings of missed approach procedures; and inconsistent manuals for air traffic control and pilots were "a hazard.'' 

Investigators said a review of air traffic management systems at Queenstown was prudent and recommended to the director of civil aviation that he ensure a plan for Queenstown aerodrome addressed safety issues, clarified manuals and installed a system to give real-time weather observations behind Deer Park Hill.

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