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Analysis

Summary

Air traffic control

The trainee had never communicated traffic information under these circumstances before and was unsure of exactly how to do so. The trainee had also not had to pass any traffic information during the training period on sector 10. This situation may have contributed to the delayed transmission.

The fact that the training officer and trainee had different preferred methods of notating flight strips and dealing with traffic conflictions near the control area boundary, may have caused some misunderstanding between the trainee and the training officer which, in turn, may have led to the delay in the training officer's prompt.

Flight service

Had the trainee controller not volunteered to pass the traffic information, the decision of the flight service officer to wait for the Brasilia crew to make their general broadcast on the FIS 7 frequency before passing traffic information on the Dash 8, may have resulted in the Brasilia passing through the level of the Dash 8 before the crew received the traffic information.

The predication that the crew of the Brasilia would contact him at "top of descent" did not allow for any of the delays that occurred. It did not allow for the fact that air traffic control generally obtain a pilot report of "leaving" a level before instructing that crew to transfer to the FIS frequency and that a pilot may wait up to one minute after leaving a level before making that report to air traffic control.

Crew of the Brasilia

Due to the short notice given to the pilot in command of the Brasilia about the Dash 8, he had to make a decision on whether to continue the descent. His choice to continue visually, even though he had not yet sighted the Dash 8 or made radio contact with the crew, was made when there was no separation assurance provided by the manoeuvre. However, the pilot in command of the Brasilia had sighted the Dash 8, while still in controlled airspace, and elected to continue descent on a "see and avoid" basis until radio contact was achieved.

This decision also meant that, due to the frequency congestion, the required broadcast on the FIS 7 frequency was not made until the Brasilia was outside controlled airspace.

Documentation

Aeronautical Information Publication

The AIP allows a pilot of an instrument flight rules aircraft to proceed on a "see and avoid" basis under visual flight rules when in visual meteorological conditions. These procedures were designed when the majority of aircraft were comparatively slow and operated at altitudes below 10,000 ft and may not be appropriate at 20,000 ft with aircraft closing speeds in the region of 500 knots. Whether this option should be allowed in all circumstances may need to be reviewed.

Manual of Air Traffic Services

The guidance for air traffic service officers in relation to traffic assessment in class "G" airspace was not specific in regard to the timely passing of traffic information and coordination. Judgement was left to the experience of individual officers and tended to vary from person to person.

 
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