TCAS on show

The loss of separation incident involving two Qantas A330s near Adelaide Australia on Friday September 19 serves to highlight the multiple levels of safety built into the airline industry today.

Qantas Flt 576 was heading from Perth to Sydney at 39,000ft when the Airbus A330’s pilots received an alert from the aircarft's Traffic Collision Avoidance System (TCAS).

It climbed to avoid Qantas Flt 581, which had been given an instruction from air traffic control to climb.

Flight 581, also an A330, was heading from Sydney to Perth at 38,000ft when its pilots asked for permission to climb.

That permission was given by Airservices Melbourne Air Traffic Control centre but was rescinded shortly afterwards when the error was apparently detected, but not before the TCAS alerts were activated.

Airservices ATC system also has an alert system called Short Term Conflict Alert but it is yet known if that activated.

While the aircraft came within 700ft of vertical separation it is yet to be determined what lateral separation they had.

The standard in Australia is 1000ft (305m) vertical and 5 nautical miles (9km) lateral.

Initially it was reported that the aircraft were on reciprocal tracks but some sources tell AirlineRatings.com that the aircraft may have been 1nm apart.

Qantas confirmed the incident and said its pilots followed ATC instructions.

Qantas chief pilot Phil Green said the airline was “full of praise for the pilots involved”.

“These pilots have years of experience and handled the 8situation exactly as they have been trained to,” Capt. Green said.

The Australian Transport Safety Bureau the country’s crash investigator called the near miss “serious” and has started an investigation.

Australia has had 53 serious loss of separation incidents in the past 10 years.

TCAS was developed through the 70s and 80s and became mandated in the 1990s.

All commercial aircraft seating more than 30 passengers (In some countries 19) must have TCAS fitted.

To read how it works see here.