Go around due to traffic.

Attributes
ACN	552138
Time
Date	200207
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bos.airport
State Reference	MA
Altitude	agl single value : 400
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : a90.tracon tower : bos.tower
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	landing : go around
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tower : bos.tower
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	landing : roll
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : private pilot : multi engine pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 150 flight time total : 14000 flight time type : 3800
ASRS Report	552138
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	non adherence : required legal separation other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : executed go around
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	Ambiguous

Narrative:

After runway switch at bos from runway 33L to runway 4R, approach issued vectors/speeds until approximately 8 NM with runway 4R in sight. A visual approach clearance was issued by approach. At approximately 400 ft AGL a go around issued by tower. Preceding aircraft did not exit runway in timely manner. Uneventfully missed approach and return to land runway 4R.

Original NASA ASRS Text

Title: GAR DUE TO TFC.

Narrative: AFTER RWY SWITCH AT BOS FROM RWY 33L TO RWY 4R, APCH ISSUED VECTORS/SPDS UNTIL APPROX 8 NM WITH RWY 4R IN SIGHT. A VISUAL APCH CLRNC WAS ISSUED BY APCH. AT APPROX 400 FT AGL A GAR ISSUED BY TWR. PRECEDING ACFT DID NOT EXIT RWY IN TIMELY MANNER. UNEVENTFULLY MISSED APCH AND RETURN TO LAND RWY 4R.

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.