A319
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Environment - Non Weather Related; Procedure
Transitioning from GOATZ ONE arrival to the ILS 25 left. Sequenced closely behind aircraft approximately 3 miles ahead. We were directed to maintain 170 kts to Lima. We intercepted the glideslope at 5;000 feet and soon after started experiencing up to moderate turbulence associated with wake vortices from the aircraft ahead. I inquired as to the type of aircraft we were following and eventually got the answer that we were behind a 757. I directed the FO [First Officer] who was flying to slow to increase separation and informed Approach that we were experiencing moderate turbulence due to too close spacing. Spacing was increased to approximately 4 nm for an uneventful landing. This event occurred because the FAA has decided that it is safe and has made it legal to sequence smaller aircraft behind a 757 as if it were a 737 or AB320 ie. 3 nm. The legal distance used to be 4 nm and rightly so. Last year I submitted a similar debrief where we were sequenced 3 nm behind a 757 and experienced an aircraft upset of over 30 [degrees] angle of bank. When we attempted to right the ship; the flight controls did not respond for 2-3 secs and then degraded to alternate law at approximately 1;500 feet. We stabilized the aircraft and continued to an uneventful landing. Once at the gate; Maintenance advised us that the FO's AOA probe had actually broken loose. The aircraft was subsequently downed for the rest of the day. At that time I called and debriefed Los Angeles Approach Control and Tower on the issue. As it turned out there was no need to sequence us that close behind the 757; there was plenty of room behind us. I thought something would finally be done to re-institute the 4 nm safety sequence but apparently not. How many more planes do we have to break and how many more passengers do we need to scare before we realize that there was a reason why there used to be a longer spacing behind a 757 due to its strong wake vortices? I find it very hard to believe that one more mile behind a 757 is going to greatly affect the landing efficiencies at airports; whereas I am sure it will increase safety and comfort for crews and the flying public.
A319 Captain reported encountering wake turbulence on arrival into LAX in trail of a B757. Reporter expressed concern with the new procedures allowing closer sequencing behind B757 aircraft.