The ATSB on Wednesday released four preliminary reports covering six incidents at Kingsford Smith Airport between July and August. The reports do not make findings or recommendations but outline the sequence of events.
On July 27, a "breakdown of coordination" led an air traffic controller to clear a Boeing 737 carrying 157 people to cross a runway as a QantasLink Bombardier carrying 55 people was landing. The controller had a "high predicted fatigue risk level" when a brief handover was given to another controller during a break.
ATSB Commissioner Angus Mitchell said the July 27 incident was a "Category A runway incursion", the most severe classification, and only the third such event in Australia since records began in 2003.
"[The 737] had stopped before reaching the intersection of runway 34L and runway 25 but was within the runway surface area past the runway stop bars, resulting in a runway incursion," the report said. "[The Bombardier] came to a stop prior to the runway 34L and 25 runway intersection. When both aircraft came to a stop, they were approximately 120 m apart."
The report said Sydney's air traffic control tower was operating with high predicted fatigue levels for four out of seven controllers at the time.
"Whilst an elevated fatigue risk does not necessarily mean a controller was fatigued, or that fatigue affected performance, we are, however, examining the effectiveness of the measures that were in place to manage this pre-identified risk," Mr Mitchell said.
"In all six incidents, safety defences operated in some form; air traffic controllers, pilots or ground crew acted to prevent more serious outcomes," he said.
Airservices Australia roster modelling had predicted an "elevated fatigue risk" for staff on many of the shifts in question, the report said.