B747 crew turned inside the aircraft they were cleared to follow.

Attributes
ACN	475483
Time
Date	200006
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : anc.airport
State Reference	AK
Altitude	msl single value : 3500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : a11.tracon tower : lga.tower
Operator	common carrier : air carrier
Make Model Name	B747-C/F
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : a11.tracon
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer pilot : cfi pilot : multi engine pilot : atp
Experience	flight time total : 9300
ASRS Report	475483
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : private pilot : flight engineer
Experience	flight time last 90 days : 210 flight time total : 20000
ASRS Report	475377
Events
Anomaly	non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued alert controller : issued new clearance
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

First officer flying visual approach. We were instructed to follow an aircraft which was on final behind another air carrier Z aircraft. Our crew thought that the air carrier Z aircraft (which we had in sight) was the air carrier Y one we were to follow and turned a base leg between the two on final. We were then advised that we had turned between the two and to break off our base leg, leveloff and do a 270 degree turn to a final behind the air carrier Y aircraft. Safety was not compromised as we were never closer than several mi from either aircraft and inconvenienced no one other than ourselves. Landing was uneventful. Specific information that there were 2 aircraft on final given to us by the controller may have prevented us from turning base too soon. TCASII was not activated as there was no conflict.

Original NASA ASRS Text

Title: B747 CREW TURNED INSIDE THE ACFT THEY WERE CLRED TO FOLLOW.

Narrative: FO FLYING VISUAL APCH. WE WERE INSTRUCTED TO FOLLOW AN ACFT WHICH WAS ON FINAL BEHIND ANOTHER ACR Z ACFT. OUR CREW THOUGHT THAT THE ACR Z ACFT (WHICH WE HAD IN SIGHT) WAS THE ACR Y ONE WE WERE TO FOLLOW AND TURNED A BASE LEG BTWN THE TWO ON FINAL. WE WERE THEN ADVISED THAT WE HAD TURNED BTWN THE TWO AND TO BREAK OFF OUR BASE LEG, LEVELOFF AND DO A 270 DEG TURN TO A FINAL BEHIND THE ACR Y ACFT. SAFETY WAS NOT COMPROMISED AS WE WERE NEVER CLOSER THAN SEVERAL MI FROM EITHER ACFT AND INCONVENIENCED NO ONE OTHER THAN OURSELVES. LNDG WAS UNEVENTFUL. SPECIFIC INFO THAT THERE WERE 2 ACFT ON FINAL GIVEN TO US BY THE CTLR MAY HAVE PREVENTED US FROM TURNING BASE TOO SOON. TCASII WAS NOT ACTIVATED AS THERE WAS NO CONFLICT.

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.