Apropos Adelaide near hit, read this
What happened when the fool proof TCAS collision avoidance system told an EasyJet flight to DESCEND,DESCEND CROSSING while advising a nearby Air France jet to DESCEND, DESCEND NOW near Basel and why it is important in Australia
On 20 September
two Qantas A330s flying in opposite directions between Sydney and Perth experienced a ‘near hit’ because of an AirServices Australia error which has lead to a current ATSB inquiry.
The report in
Plane Talking linked above gave rise to a furious discussion, including the view that there was really nothing to see, we ought to move on, it was just a controller mistake, and TCAS, the collision warning system carried by all aircraft of a certain size and capability, would have saved the day.
A report in France about a very near miss between two A319s in 2010, one flown by Air France and the other EasyJet, near Basel’s Mulhouse airport, suggests otherwise.
For a number of reasons discussed in the
Aviation Herald’s summary of the report which would be,
quelle surprise, in French, the RA or resolution advisory issued to the pilots of the easyJet flight changed from DESCEND, DESCEND CROSSING to CLIMB, CLIMB NOW in two seconds.
At the same time easyJet was told DESCEND, DESCEND CROSSING, Air France was told DESCEND, DESCEND NOW.
The abrupt reversal of the TCAS advisory to the easyJet pilots caused them to climb so suddenly that their jet pulled 2.04 G while rolling into a left turn with an angle of bank of 30 degrees, injuring a cabin attendant.
This wasn’t just a breakdown of separation, but a highly unusual TCAS event, and one that did not conform to the gentle almost unnoticeable changes in direction that are considered almost universal in TCAS directed air space conflict resolutions.
Caution: The airport, its surrounding topography, and the equipment used by ATC system, and their training courses, were all, of course, different to those that applied in the Adelaide incident.
However, training and performance errors, and the need to accommodate airliners when they need to divert around severe storm cells, are issues shared in common by ATC in Australia and elsewhere in the world.
One of the reasons why the French safety investigator, the BEA has conducted an inquiry and published its findings is the relevance of the incident to ALL airlines and ATC systems, and while some might think otherwise, Australia is part of the world, and this does have points of relevance to Australian practice as all the parties strive to learn from incidents, relate them to their own circumstances, and enhance air safety as a consequence.
It’s not a case of move on, nothing to see, but one of studying and learning and not saying stupidly dangerous things about TCAS.