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The crew of a departing Boeing 737 (B737) reported that as they were climbing to 5,000 ft on a standard instrument departure from runway 27 at Melbourne, they saw an arriving B737 on descent in their 12 o'clock position, passing from right to left. The departing aircraft's traffic alert and collision-avoidance system indicated that there might have been less than the required radar separation standard of 3 NM between the two aircraft. The crew was not alerted by air traffic control regarding the arriving B737.

Radar data and air traffic control automatic voice recordings were reviewed to establish the sequence of events. The investigation found that the Departures controller had assigned responsibility for separation to the pilot of the arriving B737, which was tracking for left downwind runway 34. The transmission from air traffic control to the crew of the descending B737 included the statement "...clear of the 737 out to your left, descend to 3000".

Airservices Australia advised that the procedure was used when separating runway 27 departing aircraft from arriving aircraft tracking on left downwind for runway 34. The aim was to release the climb and descent restrictions of both aircraft as soon, and as efficiently, as possible. The procedure of one aircraft sighting and confirmed past the other aircraft was considered to be a legitimate technique in such situations.

Visual separation of air traffic may have been a valid method to use in those circumstances. However, the criteria for its application were clearly detailed in the Manual of Air Traffic Services (MATS) Part 4 Section 5. In particular, MATS 4.5.1.11 stated: "In circumstances where an aircraft has been instructed to maintain separation from, but not follow, an IFR aircraft, traffic information shall be issued to the IFR aircraft, including advice that responsibility for separation has been assigned to the other aircraft". The departing B737 was an IFR aircraft but was not provided with the required traffic information.

 

As a result of this investigation, Airservices Australia provided the Australian Transport Safety Bureau with the following response. "The information you provided with respect to the application of visual separation as per MATS 4.5.1.11 was discussed with some and forwarded to all Business Unit procedures specialists for appropriate action. Additionally, it was forwarded to local QA areas and DSEA audit for follow up ensuring the ongoing correct application of this procedure".

 
General details
Date: 18 April 2001 Investigation status: Completed 
Time: 1458 hours EST  
Location   (show map):5 km W Melbourne, (VOR) Investigation type: Occurrence Investigation 
State: Victoria Occurrence type: ANSP info/procedural error 
Release date: 04 February 2002 Occurrence class: Airspace 
Report status: Final Occurrence category: Incident 
 Highest injury level: None 
 
Aircraft 1 details
Aircraft manufacturer: The Boeing Company 
Aircraft model: 737 
Aircraft registration: VH-TAX 
Serial number: 23489 
Type of operation: Air Transport High Capacity 
Damage to aircraft: Nil 
Departure point:Melbourne, VIC
Destination:Perth, WA
Aircraft 2 details
Aircraft manufacturer: The Boeing Company 
Aircraft model: 737 
Aircraft registration: VH-CZF 
Serial number: 23658 
Type of operation: Air Transport High Capacity 
Damage to aircraft: Nil 
Departure point:Unknown
Destination:Melbourne, VIC
 
 
 
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Last update 13 May 2014