The crew of the Beech 1900D (B1900) aircraft had been cleared by
the aerodrome controller (ADC) 1 to descend to 4,000 ft and were
instructed to join the circuit via a left base leg for runway 12L
(northern) circuit at Tamworth. The ADC 1 also instructed the crew
to report approaching 4,000 ft. The crew acknowledged the clearance
but later advised that they were unable to report approaching 4,000
ft due to frequency congestion. The ADC 1 had assigned 4,000 ft so
that a procedural separation standard of 1,000 ft could be
maintained with other aircraft until he could see the B1900 and
apply visual separation.
The crew of the B1900 subsequently requested confirmation of
their assigned level and reported their position when at 2NM north
of the aerodrome. The controller then sighted the aircraft and
cleared the crew to make a visual approach. The controller also
asked the crew if they would need to extend through the centreline
of runway 12L. The crew acknowledged the visual approach but did
not advise the controller that they would need to extend through
the centreline. The visual approach clearance authorised the crew
to descend below 4,000 ft.
The crew of the B1900 could not comply with the instruction to
join the circuit via a left base for runway 12L because the
aircraft was too high and too fast. The co-pilot was the non-flying
pilot and was undergoing command upgrade training. He had
acknowledged the clearance for the visual approach and had
previously acknowledged the instruction to join the northern
circuit via a left base leg for runway 12L. At the time that the
visual approach clearance was issued, the pilot-in-command was
aware that they could not comply with the circuit entry
instruction. He believed that the controller would have been aware
that they were unable to enter the circuit on a left base leg,
given their proximity to the circuit at that time and the height
and speed of the aircraft. He also believed that the controller
would have taken those circumstances, and the disposition of
traffic in the southern circuit, into account when issuing the
visual approach instruction.
The B1900 continued to descend and entered the runway 12R
(southern) circuit airspace which was under the control of the ADC
2. The ADC 1 notified the ADC 2 that the B1900 had entered the
southern circuit. The ADC 2 advised the ADC 1 that there was a
Pacific Aerospace Corporation Airtrainer CT4B (CT4) on a right base
leg for runway 12R. The ADC 2 provided traffic information about
the B1900 to the crew of the CT4. There were four other CT4
aircraft inbound to the circuit at that time but the ADC 2 had not
sighted them. The ADC 1 was unable to apply the required separation
standard, either 1,000 ft vertically, or a minimum horizontal
distance determined using the appropriate `Lateral Separation'
standard from the Manual of Air Traffic Services (MATS), between
the B1900 and the traffic inbound to the southern circuit. There
was an infringement of separation standards.
The ADC 1 reported that he had sighted the CT4 on right base. He
then instructed the crew of the B1900 to make a right turn and
track via a right base leg for runway 12L. He believed that the
B1900 was visually separated from that CT4 and that he could
maintain visual separation between the B1900 and that CT4 with that
instruction. He did not think that there had been an infringement
of separation standards between the B1900 and the aircraft inbound
to the southern circuit because all parties had enough time to
ensure that visual separation was not infringed.