Question for any Airbus guys/gals.

I'm not familiar with the systems and acronyms of the 'Bus and how they affect the cockpit instruments.

Based on your knowlege, did the crew have some sort of reliable (backup) indications of airspeed, altitude, attitude, and vertical speed.

Would the backup systems work?

I'm kind of scratching my head thinking if the crew didn't have reliable indications on their instruments then there is no way they would have known what was wrong then therefore no way to correct the problem.

So, based on your experience, was back information available and was it reliable.

Thanks.