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.
How many software updates have there been to TCAS software since 2010?
This page gives an example like the one cited by Ben which might explain waht happened in the EasyJet/Air France case.