Maximum range for the TCAS to display a target is only 40 NM ...
Well, the press report is ambigous (for a change), but I also did see the Iberia pilot interviewed in a TV program.
The recap, this time in my own words is:
-They took off 7 minutes later on the A320 to follow "dead on" the tail of the AF 330
-At some point, they had TCAS contact and the captain had an eye on it to monitor, as they were sharing the route and fairly close.
-The Iberia pilot believed the AF was about 80 miles dead straight ahead when he noticed bad patch of weather coming and decided to start a change in the scheduled course and turn east some 30 miles to circunvent it (potentially leaving the AF, around 8 minutes ahead, in a course to go through this rough weather patch). He believes this coincided almost exactly when the moment the AF went "missing".
-The Iberia pilot wasn't really "afraid" for the AF when they weren't answering ATC figuring perhaps they had a transporder/communication problems as, in his opinion, there was nothing unusual at all with the weather or circunstances around the area, in spite of some "normal" rough patches. He was surprised to later find out the AF had likely crashed as he couldn't figure out a situation with such high risk of accident (at all), in spite of occasional bad weather spots. He insists circunstances were well within, and even "below", normal for the route, while not "perfect" or "great", but not unusually bad or even "strong". Just plain old bad-ish. Certainly nothing in his opinion to warrant a high risk of accident. Of course, he wants to make clear that, in the aprox. 8 minutes that separated them, the weather could've changed quite a bit as it's unpredictable, but he just can't believe it could've turned so bad as to endanger the AF to the point of catastrophy, but with the weather, everything is, of course, possible.
FWIW