MD88 flight crew experienced conflict with preceding aircraft during visual approach to lga.

Attributes
ACN	620438
Time
Date	200405
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : lga.vor
State Reference	NY
Altitude	msl bound lower : 1000 msl bound upper : 1200
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : lga.tower
Operator	common carrier : air carrier
Make Model Name	MD-88
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tower : lga.tower
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 : visual
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 46 flight time total : 8500 flight time type : 3500
ASRS Report	620438
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne critical non adherence : required legal separation
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 500 vertical : 100
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Established on visual to runway 31 at lga when tower called traffic to follow at 12 O'clock position. The captain and I saw an aircraft at approximately 12 O'clock position, turning around shea stadium on 1-2 mi final. We were 2 mi inbound from point 'dials' (about 4 mi from landing). We were following air carrier Y to final. When 1 1/2 mi from touchdown (circling around shea stadium ourselves), the TCASII RA called 'traffic' as tower directed a hard right turn. I saw an aircraft approximately 500 ft away at co-altitude also tracking inbound to runway 31. We executed the avoidance maneuver and rejoined final. Tower later told us that the aircraft we barely avoided air carrier Z, had been preceding us on the expressway visual but had 'extended their final' by some maneuver that resulted in them rejoining the published maneuver at the same place and time as us. We were cleared for and established on the published visual approach procedure and notified to follow traffic 3 mi ahead. This made sense. When air carrier Z showed up out of no where, tower indicated that we were supposed to follow him! Since he had deviated from the published maneuver (and was off somewhere getting spacing), we did not see him. If we were 4 mi out, how could tower have 1 aircraft at 1 mi out and we be #3 for landing? Tower lost situational awareness on air carrier Z and did not notify us of his position or that he was rejoining the visual ground track. A near midair was the result.

Original NASA ASRS Text

Title: MD88 FLT CREW EXPERIENCED CONFLICT WITH PRECEDING ACFT DURING VISUAL APCH TO LGA.

Narrative: ESTABLISHED ON VISUAL TO RWY 31 AT LGA WHEN TWR CALLED TFC TO FOLLOW AT 12 O'CLOCK POS. THE CAPT AND I SAW AN ACFT AT APPROX 12 O'CLOCK POS, TURNING AROUND SHEA STADIUM ON 1-2 MI FINAL. WE WERE 2 MI INBOUND FROM POINT 'DIALS' (ABOUT 4 MI FROM LNDG). WE WERE FOLLOWING ACR Y TO FINAL. WHEN 1 1/2 MI FROM TOUCHDOWN (CIRCLING AROUND SHEA STADIUM OURSELVES), THE TCASII RA CALLED 'TFC' AS TWR DIRECTED A HARD R TURN. I SAW AN ACFT APPROX 500 FT AWAY AT CO-ALT ALSO TRACKING INBOUND TO RWY 31. WE EXECUTED THE AVOIDANCE MANEUVER AND REJOINED FINAL. TWR LATER TOLD US THAT THE ACFT WE BARELY AVOIDED ACR Z, HAD BEEN PRECEDING US ON THE EXPRESSWAY VISUAL BUT HAD 'EXTENDED THEIR FINAL' BY SOME MANEUVER THAT RESULTED IN THEM REJOINING THE PUBLISHED MANEUVER AT THE SAME PLACE AND TIME AS US. WE WERE CLRED FOR AND ESTABLISHED ON THE PUBLISHED VISUAL APCH PROC AND NOTIFIED TO FOLLOW TFC 3 MI AHEAD. THIS MADE SENSE. WHEN ACR Z SHOWED UP OUT OF NO WHERE, TWR INDICATED THAT WE WERE SUPPOSED TO FOLLOW HIM! SINCE HE HAD DEVIATED FROM THE PUBLISHED MANEUVER (AND WAS OFF SOMEWHERE GETTING SPACING), WE DID NOT SEE HIM. IF WE WERE 4 MI OUT, HOW COULD TWR HAVE 1 ACFT AT 1 MI OUT AND WE BE #3 FOR LNDG? TWR LOST SITUATIONAL AWARENESS ON ACR Z AND DID NOT NOTIFY US OF HIS POS OR THAT HE WAS REJOINING THE VISUAL GND TRACK. A NEAR MIDAIR WAS THE RESULT.

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.