Air carrier X TCASII RA had less than standard wake turbulence separation from DC10.

Attributes
ACN	307251
Time
Date	199506
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : sfo
State Reference	CA
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak tracon : bal
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	DC-10 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 10000 flight time type : 3000
ASRS Report	307251
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 16500 flight time type : 1350
ASRS Report	307249
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : clearance other anomaly
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Miss Distance	horizontal : 700 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Air carrier X base leg for runway 28L with 737 traffic at 10 O'clock and DC10 traffic at 2 O'clock. Rather than a dogleg turn on to runway 28L, controller issued a square turn to final. During turn we got a TCASII 'reduce descent' from DC10 behind us, which we complied with, and resolved. Controller issued clearance for visual to runway 28L, to follow the 737 for runway 28R, maintain at least 180 KTS to brijj, and contact tower. On final DC10 pulled abeam, and then passed us. We were fortunate to have a left crosswind, and flew high on GS, and landed safely. I think that there were 3 problems in this situation: 1) the controller should have given us a dogleg intercept for better spacing on the DC10. I don't know if he issued a speed or follow us instruction to the DC10. 2) the DC10 should not have passed us on final, even on a visual approach. 3) we should have gone around once the DC10 passed us. Supplemental information from acn 307249: while on a visual approach to sfo airport on the localizer for runway 28L (above GS) descending we received a red alert (RA) TCASII warning telling us to reduce descent. Shortly after complying with the RA warning a DC10 that we had in sight earlier passed us off our right and below. We continued the approach and landed. I believe the only way to correct the above situation is to reduce the traffic at that airport. The controller was obviously overloaded and couldn't monitor the traffic like he should have, he should have slowed the DC10.

Original NASA ASRS Text

Title: ACR X TCASII RA HAD LESS THAN STANDARD WAKE TURB SEPARATION FROM DC10.

Narrative: ACR X BASE LEG FOR RWY 28L WITH 737 TFC AT 10 O'CLOCK AND DC10 TFC AT 2 O'CLOCK. RATHER THAN A DOGLEG TURN ON TO RWY 28L, CTLR ISSUED A SQUARE TURN TO FINAL. DURING TURN WE GOT A TCASII 'REDUCE DSCNT' FROM DC10 BEHIND US, WHICH WE COMPLIED WITH, AND RESOLVED. CTLR ISSUED CLRNC FOR VISUAL TO RWY 28L, TO FOLLOW THE 737 FOR RWY 28R, MAINTAIN AT LEAST 180 KTS TO BRIJJ, AND CONTACT TWR. ON FINAL DC10 PULLED ABEAM, AND THEN PASSED US. WE WERE FORTUNATE TO HAVE A L XWIND, AND FLEW HIGH ON GS, AND LANDED SAFELY. I THINK THAT THERE WERE 3 PROBS IN THIS SIT: 1) THE CTLR SHOULD HAVE GIVEN US A DOGLEG INTERCEPT FOR BETTER SPACING ON THE DC10. I DON'T KNOW IF HE ISSUED A SPD OR FOLLOW US INSTRUCTION TO THE DC10. 2) THE DC10 SHOULD NOT HAVE PASSED US ON FINAL, EVEN ON A VISUAL APCH. 3) WE SHOULD HAVE GONE AROUND ONCE THE DC10 PASSED US. SUPPLEMENTAL INFO FROM ACN 307249: WHILE ON A VISUAL APCH TO SFO ARPT ON THE LOC FOR RWY 28L (ABOVE GS) DSNDING WE RECEIVED A RED ALERT (RA) TCASII WARNING TELLING US TO REDUCE DSCNT. SHORTLY AFTER COMPLYING WITH THE RA WARNING A DC10 THAT WE HAD IN SIGHT EARLIER PASSED US OFF OUR R AND BELOW. WE CONTINUED THE APCH AND LANDED. I BELIEVE THE ONLY WAY TO CORRECT THE ABOVE SIT IS TO REDUCE THE TFC AT THAT ARPT. THE CTLR WAS OBVIOUSLY OVERLOADED AND COULDN'T MONITOR THE TFC LIKE HE SHOULD HAVE, HE SHOULD HAVE SLOWED THE DC10.

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.