A C550 crew continued to airport when traffic they were to follow flew through the localizer.

Attributes
ACN	510538
Time
Date	200105
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bur.airport
State Reference	CA
Altitude	msl single value : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	general aviation : corporate
Make Model Name	Citation II S2/Bravo
Operating Under FAR Part	Part 91
Navigation In Use	ils localizer only : 8
Flight Phase	descent : approach
Route In Use	approach : visual arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : multi engine
Experience	flight time last 90 days : 75 flight time total : 13000 flight time type : 4000
ASRS Report	510538
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	non adherence : required legal separation non adherence : published procedure non adherence : clearance other anomaly other other spatial deviation
Independent Detector	aircraft equipment : tcas other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : took precautionary avoidance action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 0 vertical : 500
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Inter Facility Coordination Failure Operational Error Pilot Deviation

Narrative:

We were approaching the approach to runway 8 from the wsw to follow a B737 coming in from the north. Upon calling the B737 in sight, we were told to turn to 070 degrees and intercept localizer and descend to 3500 ft until established, then cleared for visual approach behind the B737 with additional instructions to cross vny above 3000 ft. Also instructed at this time to slow to 170 KTS. At this time the B737 was 2 1/2 mi away and about 1000 ft below. As we turned the distance closed, so we leveled off and continued to slow further to keep the B737 in sight off the nose. The B737 rolled wings level and continued south across the final. Not knowing why he did this or what his intentions were, I elected to stay on the localizer course. The B737 continued south for about 2 mi then made a left 180 degree turn to reintercept final. Approach told us to continue as #1 and contact the tower. Tower cleared us to land and asked if approach had pointed the B737 out to us and we acknowledged that they had. 2 problems: 1) ATC vectored us too close, and 2) the B737 didn't explain his deviation. Not knowing his intentions, we elected to continue directly to the airport rather than follow an aircraft whose intentions were unclr.

Original NASA ASRS Text

Title: A C550 CREW CONTINUED TO ARPT WHEN TFC THEY WERE TO FOLLOW FLEW THROUGH THE LOC.

Narrative: WE WERE APCHING THE APCH TO RWY 8 FROM THE WSW TO FOLLOW A B737 COMING IN FROM THE N. UPON CALLING THE B737 IN SIGHT, WE WERE TOLD TO TURN TO 070 DEGS AND INTERCEPT LOC AND DSND TO 3500 FT UNTIL ESTABLISHED, THEN CLRED FOR VISUAL APCH BEHIND THE B737 WITH ADDITIONAL INSTRUCTIONS TO CROSS VNY ABOVE 3000 FT. ALSO INSTRUCTED AT THIS TIME TO SLOW TO 170 KTS. AT THIS TIME THE B737 WAS 2 1/2 MI AWAY AND ABOUT 1000 FT BELOW. AS WE TURNED THE DISTANCE CLOSED, SO WE LEVELED OFF AND CONTINUED TO SLOW FURTHER TO KEEP THE B737 IN SIGHT OFF THE NOSE. THE B737 ROLLED WINGS LEVEL AND CONTINUED S ACROSS THE FINAL. NOT KNOWING WHY HE DID THIS OR WHAT HIS INTENTIONS WERE, I ELECTED TO STAY ON THE LOC COURSE. THE B737 CONTINUED S FOR ABOUT 2 MI THEN MADE A L 180 DEG TURN TO REINTERCEPT FINAL. APCH TOLD US TO CONTINUE AS #1 AND CONTACT THE TWR. TWR CLRED US TO LAND AND ASKED IF APCH HAD POINTED THE B737 OUT TO US AND WE ACKNOWLEDGED THAT THEY HAD. 2 PROBS: 1) ATC VECTORED US TOO CLOSE, AND 2) THE B737 DIDN'T EXPLAIN HIS DEV. NOT KNOWING HIS INTENTIONS, WE ELECTED TO CONTINUE DIRECTLY TO THE ARPT RATHER THAN FOLLOW AN ACFT WHOSE INTENTIONS WERE UNCLR.

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.