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An ATSB interim factual investigation report has found that the airspace incident near Brisbane on 7 April involving a B737 and a Lancair aircraft was not an 'airprox' event.

In this incident, the two aircraft passed with 600 feet vertical and 0.4NM (about 1 km) lateral separation in new Class E airspace, but were not in danger of collision.

Unlike the Launceston airprox last Christmas Eve, in this incident the smaller Lancair aircraft was on air traffic control radar and in communication with controllers and the B737 aircraft had initiated a change of flightpath before receiving two TCAS alerts.

The Lancair pilot informed the controller that he had the B737 in sight. While the B737 crew were unable to see the Lancair, they noted its presence on TCAS prior to the TCAS traffic advisory (TA) and resolution advisory (RA) alerts and they also received three reports of traffic from the air traffic controller.

The ATSB's interim factual report states that the Boeing 737-7BX, operating under the instrument flight rules (IFR), was en route from Townsville and descending for a landing at Brisbane, while the Neico Lancair IV-P, operating under visual flight rules (VFR), was en route from Maroochydore to St George, on climb to flight level (FL)165.

As the B737 was approaching FL 157, the crew noted the Lancair via the aircraft traffic alert and collision avoidance system (TCAS). At that point the crew reduced the rate of descent. Thirty seconds later they received a TCAS TA. Recorded data from the B737's flight data recorder indicated that the crew levelled the B737 at FL 153, and then climbed to FL 154 and commenced a right turn away from the Lancair.

About 22 seconds later, the crew received a TCAS RA instructing them to climb. They subsequently climbed the B737 to FL 166 and continued the right turn to about 15 degrees right of track. Recorded radar data indicated that the Lancair passed behind and below the B737. The minimum distance between the two aircraft was about 600 feet vertically and 0.4 NM laterally.

Information obtained from the crews of both aircraft, the Airservices ATS controller, recorded flight data from the B737, ATS audio recordings and radar data, is consistent and indicates that the crews of both aircraft and the ATS controller complied with the published procedures for Class E airspace under NAS 2b.

 

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Last update 01 April 2011