Aircraft vectored to final approach intercept was turned on centerline late, crossed into parallel r...

Attributes
ACN	333634
Time
Date	199604
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : sfo
State Reference	CA
Altitude	msl bound lower : 4000 msl bound upper : 5000
Environment
Flight Conditions	Mixed
Light	Night
Aircraft 1
Controlling Facilities	tracon : sfo
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer pilot : cfi
Experience	flight time last 90 days : 100 flight time total : 11000 flight time type : 3000
ASRS Report	333634
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	inflight encounter other non adherence : required legal separation non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Because of traffic and WX, we held for 1 hour 40 mins at both eni and pye. Sfo was landing on runways 19. When the WX passed through, sfo was using visuals to runways 28. We were given a heading down the north side of the bay (100 degrees) and a descent to 6000 ft. Approach said, 'you are number 5 after a B757 on a 20 mi final.' we were between the san mateo and dumbarton bridges when approach gave us a descent to 5000 ft and a heading of 180 degrees (there were scattered clusters of clouds still remaining). Approach said, 'descend to 4000 ft, then slow to 180 KTS. I saw the lights of another aircraft pass below and in front of us. Approach said 'report the airport,' which we did, and he said 'cleared visual runway 28R and report traffic for the left, a B757.' the lights and the TCASII showed the B757 to be at 2 mi. I didn't report the traffic, but asked, 'how far ahead is the B757?' approach replied, '4 mi, but he's staggered for the left and below you.' I immediately slowed to approach speed, and nibbled at the B757 wake all the way to touchdown. Several things were wrong: 1) we were joined on a B757 with less than legal separation, and we never reported him in sight. 2) the 180 degree heading caused us to overshoot the runway 28R centerline. 3) the controller stated that we were 'staggered,' implying that the B757 was for runway 28L. However, the separation of the runways (750 ft) makes them one runway for wake turbulence considerations. Also, just because he was below us is immaterial. Callback conversation with reporter revealed the following information: reporter suggests ways to improve ATC procedures to prevent wake turbulence encounters: notify flight crew about following B757 aircraft, follow proper spacing as per ATC handbook instructions concerning spacing, don't have split frequencys for aircraft on parallel approachs, have both aircraft report visual contact with each other, but don't expect aircraft which are staggered, one in front of the other, for the front aircraft to maintain visual with one behind them. Reporter says in the future he will question approach controller about what type of aircraft he is following.

Original NASA ASRS Text

Title: ACFT VECTORED TO FINAL APCH INTERCEPT WAS TURNED ON CTRLINE LATE, CROSSED INTO PARALLEL RWY CTRLINE AND 2 MI BEHIND B757. RPTR'S ACFT EXPERIENCED LIGHT TURB FOR ENTIRE APCH, BUT STAYED HIGH ON GS TO AVOID THE MAJOR WAKE.

Narrative: BECAUSE OF TFC AND WX, WE HELD FOR 1 HR 40 MINS AT BOTH ENI AND PYE. SFO WAS LNDG ON RWYS 19. WHEN THE WX PASSED THROUGH, SFO WAS USING VISUALS TO RWYS 28. WE WERE GIVEN A HDG DOWN THE N SIDE OF THE BAY (100 DEGS) AND A DSCNT TO 6000 FT. APCH SAID, 'YOU ARE NUMBER 5 AFTER A B757 ON A 20 MI FINAL.' WE WERE BTWN THE SAN MATEO AND DUMBARTON BRIDGES WHEN APCH GAVE US A DSCNT TO 5000 FT AND A HDG OF 180 DEGS (THERE WERE SCATTERED CLUSTERS OF CLOUDS STILL REMAINING). APCH SAID, 'DSND TO 4000 FT, THEN SLOW TO 180 KTS. I SAW THE LIGHTS OF ANOTHER ACFT PASS BELOW AND IN FRONT OF US. APCH SAID 'RPT THE ARPT,' WHICH WE DID, AND HE SAID 'CLRED VISUAL RWY 28R AND RPT TFC FOR THE L, A B757.' THE LIGHTS AND THE TCASII SHOWED THE B757 TO BE AT 2 MI. I DIDN'T RPT THE TFC, BUT ASKED, 'HOW FAR AHEAD IS THE B757?' APCH REPLIED, '4 MI, BUT HE'S STAGGERED FOR THE L AND BELOW YOU.' I IMMEDIATELY SLOWED TO APCH SPD, AND NIBBLED AT THE B757 WAKE ALL THE WAY TO TOUCHDOWN. SEVERAL THINGS WERE WRONG: 1) WE WERE JOINED ON A B757 WITH LESS THAN LEGAL SEPARATION, AND WE NEVER RPTED HIM IN SIGHT. 2) THE 180 DEG HDG CAUSED US TO OVERSHOOT THE RWY 28R CTRLINE. 3) THE CTLR STATED THAT WE WERE 'STAGGERED,' IMPLYING THAT THE B757 WAS FOR RWY 28L. HOWEVER, THE SEPARATION OF THE RWYS (750 FT) MAKES THEM ONE RWY FOR WAKE TURB CONSIDERATIONS. ALSO, JUST BECAUSE HE WAS BELOW US IS IMMATERIAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR SUGGESTS WAYS TO IMPROVE ATC PROCS TO PREVENT WAKE TURB ENCOUNTERS: NOTIFY FLC ABOUT FOLLOWING B757 ACFT, FOLLOW PROPER SPACING AS PER ATC HANDBOOK INSTRUCTIONS CONCERNING SPACING, DON'T HAVE SPLIT FREQS FOR ACFT ON PARALLEL APCHS, HAVE BOTH ACFT RPT VISUAL CONTACT WITH EACH OTHER, BUT DON'T EXPECT ACFT WHICH ARE STAGGERED, ONE IN FRONT OF THE OTHER, FOR THE FRONT ACFT TO MAINTAIN VISUAL WITH ONE BEHIND THEM. RPTR SAYS IN THE FUTURE HE WILL QUESTION APCH CTLR ABOUT WHAT TYPE OF ACFT HE IS FOLLOWING.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Aircraft vectored to final approach intercept was turned on centerline late, crossed into parallel runway centerline and 2 mi behind B757. Reporter's aircraft experienced light turbulence for entire approach, but stayed high on GS to avoid the major wake.