Altitude deviation started altitude excursion during flight crew response to TCASII RA.

Attributes
ACN	218738
Time
Date	199208
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : lga
State Reference	NY
Altitude	msl bound lower : 4000 msl bound upper : 4100
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90 tower : jfk
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 1900
ASRS Report	218738
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew Other
Miss Distance	horizontal : 500 vertical : 100
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Being vectored for landing on runway 22 at lga -- 4000 ft and 070 degree heading. Given turn to 020 degrees and picked up an large transport at 11 O'clock, 2 mi, same altitude. 'TA' at this time showing '0' altitude difference. We called approach control, they said the large transport was out of 4000 ft. We continued on collision course until we got an RA to climb. (Still showing 0 ft difference in altitude). We climbed 100 ft and were turned to 070 degrees when we told approach control we had an RA. Visually, the large transport looked co-altitude. The TCASII showed him at co-altitude. When I talked to TRACON approach control later, they stated that the tapes (?) had the large transport at 3200 ft. What's going on?

Original NASA ASRS Text

Title: ALTDEV STARTED ALT EXCURSION DURING FLC RESPONSE TO TCASII RA.

Narrative: BEING VECTORED FOR LNDG ON RWY 22 AT LGA -- 4000 FT AND 070 DEG HDG. GIVEN TURN TO 020 DEGS AND PICKED UP AN LGT AT 11 O'CLOCK, 2 MI, SAME ALT. 'TA' AT THIS TIME SHOWING '0' ALT DIFFERENCE. WE CALLED APCH CTL, THEY SAID THE LGT WAS OUT OF 4000 FT. WE CONTINUED ON COLLISION COURSE UNTIL WE GOT AN RA TO CLB. (STILL SHOWING 0 FT DIFFERENCE IN ALT). WE CLBED 100 FT AND WERE TURNED TO 070 DEGS WHEN WE TOLD APCH CTL WE HAD AN RA. VISUALLY, THE LGT LOOKED CO-ALT. THE TCASII SHOWED HIM AT CO-ALT. WHEN I TALKED TO TRACON APCH CTL LATER, THEY STATED THAT THE TAPES (?) HAD THE LGT AT 3200 FT. WHAT'S GOING ON?

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.