Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 18000
Inflight Event / Encounter Wake Vortex Encounter; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Unstabilized Approach
Aircraft Aircraft Damaged; Flight Crew Regained Aircraft Control
Procedure; Environment - Non Weather Related
Approaching LOC intercept to ILS 25L LAX we were made aware of several other A/C on approach including 757 ahead of us for 25L. We were sequenced in behind the 757 very tight at just 3nm spacing. I attempted to add spacing by squaring the turn and slowing early but was told by Approach to turn to 320 and intercept; cleared the approach. Soon after intercepting the glide slope we hit minor turbulence that we assumed was the 757 wake. Within 10 secs the turbulence was so great that the A/C was temporarily uncontrollable (not responding to manual stick inputs). This was followed by an aural warning advising us that we had a NAV ADR disagree and a NAV STBY AOA fault. It also advised us we had reverted to Alternate Law and had manual trim only. We chose to continue the approach as the A/C was configured and back under control. I asked for flaps full and landing checklist. FO was reading over the faults delineated on the EICAS and apparently didn't hear my call for full flaps. We completed the check list but then somewhere around 500ft the A/C advised us that we were not in full flaps as we had programmed. We selected full and made an uneventful landing.At the gate I called LA approach and they said that there was a new rule now that made the 757 just another large A/C and that they only needed 3nm for spacing. He then apologized for the fact that we were 3.15nm in trail with 7nm spacing to the A/C behind us. The bottom line is that there is NO WAY that spacing should be just 3nm behind a 757! This upset knocked out the Normal flight control logic of the A319. Do we not remember the [A300] that went down in NY due to wake turbulence! In the throes of the upset; with the A/C not responding to inputs for a short time; all I could think of was 'STAY OFF THE RUDDERS'. One suggestion: End this new minimum separation rule for the 757!
Reporter stated he learned later that the angle of attack vane was found to be physically broken; which was the cause of the reversion to alternate law.
[Report narrative contained no additional information.]
A319 flight crew reported experiencing a momentary loss of control following a wake vortex encounter in trail of a B757 on approach to LAX.