On 25 January 2006, a Boeing Company 777-200 (777) was en route
from Christchurch, NZ, to Singapore at flight level (FL) 360. A
Boeing Company 737-838 (737) was en route from Alice Springs, NT,
to Sydney, NSW, on a reciprocal track at FL370. At 0422.30
Coordinated Universal Time the two aircraft passed each other in
the vicinity of waypoint APOMA, in the Melbourne Flight Information
Region.
The pilots of the 777 had requested a clearance to climb to
FL380. The separation standard that was applicable between the two
aircraft, before the air traffic controller could authorise climb
for the 777, was a ten minute longitudinal standard. That standard
required the controller to calculate the estimated time the two
aircraft would pass, using a method approved in the Manual of Air
Traffic Services. Once that estimated time of passing was
established, ten minutes either prior to, or after, that time of
passing had to be applied. In the circumstances, a vertical
separation standard needed to exist from the estimated time of
passing plus the ten minutes. The crew of the 777 had been
instructed to climb to FL380 at the estimated time of passing plus
8.5 minutes. There was an infringement of separation standards.
The air traffic controller's initial scan of the air situation
display was incomplete and did not detect that a procedural
separation standard would not exist between the 737 and the 777, or
that he needed to calculate the time that the 10 minute
longitudinal separation standard was established. A more
comprehensive initial scan of the air situation display by the
controller may have facilitated timely action to avoid an
infringement of separation standards.