Boeing Co 737-376 , VH-TAF

1. The similarity of the departure instruction to the noise abatement procedure provided the potential for a human error to occur.

2. The crew of TAF did not comply with the departure instruction issued by air traffic control because the crew confused the instruction with the noise abatement procedure.

3. The enroute controller did not issue TAF with a procedural clearance that would have provided separation assurance with CZV.

The investigation determined that the crew of TAF did not comply with their departure instruction. Separation would not have been infringed if TAF had continued on a heading of 090 M as directed, instead of intercepting the 128 radial. The similarity of the noise abatement procedure to the departure instruction may have diminished the importance of the requirement for the crew to maintain a heading of 090 M after departure.

Although the action of the crew resulted in an infringement of the radar separation standard, the enroute controller did not issue a clearance that assured separation between TAF and CZV. Separation assurance was required in accordance with MATS 4-1-1, paragraph 6. The controller used radar procedures to separate the two aircraft, where non-radar separation should have been applied in accordance with MATS 4-1-1 paragraph 11 because communications and equipment did not allow the application of radar separation.

The enroute controller was not in direct communication with the crews of both aircraft. Moreover, portions of Maroochydore airspace were below radar coverage including airspace below 1,500 ft. Although LOA 98/054 allowed the enroute controller to "assume radar identification of departing aircraft within four minutes of the next call", published procedures did not permit the enroute controller to apply radar separation between radar identified aircraft and aircraft departing Maroochydore that were not identified.

The crew of VH-TAF, a Boeing 737, was taxiing for runway 18 at
Maroochydore (MC) for a departure to Sydney. The route was flight
planned, and subsequently cleared, via waypoint TRIKI (128 MC at 22
NM) on air route W196 at flight level (FL) 350. The crew had
pre-briefed the noise abatement procedure that was detailed in AIP
Australia as follows:

"2.2 Departing Runway 18 - MC to TRIKI: UNLESS
OTHERWISE DIRECTED BY ATC. (a) Jet aircraft shall at 500FT, turn
left heading 090 degrees M to intercept track. If not able to
intercept track from this heading, then maintain heading 090
degrees until 4DME before turning to intercept track".

Another Boeing 737, VH-CZV, was inbound to Maroochydore from
Sydney and tracking via TRIKI on W196. The Maroochydore aerodrome
controller had received prior coordination on this aircraft, which
was on descent to 5,000 ft. Although the BURNET enroute controller
was responsible for CZV, the crew was not in two-way communication
with the enroute controller. The enroute controller had agreed to
allow the crew to transfer frequency direct from Brisbane Approach
to Maroochydore Tower. The standard frequency transfer point in
accordance with Letter of Agreement (LOA) ND 98/054 was TRIKI. CZV
was roughly 32 NM from Maroochydore when the aerodrome controller
contacted the enroute controller to coordinate a departure
clearance for TAF.

Maroochydore was a non-radar tower and the aerodrome controller
was responsible for providing procedural separation to aircraft
below 4,500 ft. The enroute controller was responsible for the
surrounding airspace overlying and to the south of Maroochydore as
defined in the AIP Designated Airspace Handbook. The enroute
controller was able to use radar or procedural means to provide air
traffic control separation. Radar coverage in the Maroochydore area
was generally available above 1,500 ft.

At 1236, the enroute controller advised the aerodrome controller
to issue TAF a heading of 090 degrees M and to maintain FL150, a
level that would provide vertical separation from a third aircraft
overflying at FL160. The aerodrome controller recognised a
potential conflict between TAF and CZV, and confirmed with enroute
that the enroute controller would accept the responsibility for
conflict resolution. The enroute controller accepted the
responsibility for providing separation.

The aerodrome controller then issued the following departure
instruction to the crew of TAF: "TAF, restriction on departure is
to turn left and take up a heading of 090 magnetic, maintain FL
150, clear for take-off, make left turn". The crew correctly read
back the instruction. The crew later reported that they interpreted
the restriction on departure to be the altitude restriction and
believed the heading instruction applied to the noise abatement
procedure. At 1238, the crew was instructed by the aerodrome
controller to contact the enroute controller to make a departure
report.

CZV meanwhile, was approaching TRIKI and the crew reported to
the Maroochydore aerodrome controller on descent to 5,000 ft. The
aerodrome controller directed the crew to continue tracking direct
to Maroochydore and to maintain 5,000 ft. Maroochydore tower then
contacted the enroute controller seeking an unrestricted descent
clearance for CZV, which was granted but not issued to the
crew.

At the same time, TAF was turning right to intercept the 128
radial at 4 NM from Maroochydore and was passing 4,400 ft on climb.
The crew contacted the enroute controller at 1239 and reported
established on the 128 radial, climbing to FL 150. TAF and CZV were
then on reciprocal tracks and closing. In an unsuccessful attempt
to preserve the required separation, the crew of TAF was told to
turn left onto a heading of 090 M and maintain 5,000 ft. The
aerodrome controller who was in two-way communication with the
enroute controller over the hotline, found that CZV was passing
5,400 ft on descent. The enroute controller asked the aerodrome
controller to direct the crew of CZV to turn right on to 090 M,
which was actioned. The enroute controller issued traffic
information to the crew of TAF about the relative position of CZV
and requested the crew to climb to FL 150 and maintain their best
rate of climb. Traffic information was not issued to the crew of
CZV about TAF.

At 1240, the required vertical separation of 1,000 ft between
the two aircraft reduced to 400 ft when the minimum radar
separation of 5 NM was infringed. The application of radar
separation and the requirements for issuing clearances were
detailed in chapters 4, 9 and 12 of the Manual of Air Traffic
Services (MATS).

The enroute controller received a short-term conflict alert
(STCA) on the radar display. However, neither of the flight crews
reported receiving a traffic alerting and collision avoidance
system (TCAS) warning from their respective aircraft's display.