Flight crew of a B727 climbed in response to a TCASII RA caused by another aircraft VFR 500 ft lower...

Attributes
ACN	383291
Time
Date	199710
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : lga
State Reference	NY
Altitude	msl bound lower : 8000 msl bound upper : 9000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : n90
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 184 flight time total : 15000 flight time type : 9000
ASRS Report	383291
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

ATC informed us of VFR traffic at 7500 ft. Our altitude was 8000 ft, at night, in broken cloud conditions. As we closed on the traffic, our TCASII indicated traffic in yellow and voiced traffic, traffic. Then the TCASII changed from yellow to red with a command of climb, climb. Our altitude had remained at 8000 ft, as the traffic altitude began to change from -500 ft to -400 ft to -300 ft to -200 ft in a matter of seconds. I ordered a climb and advised ATC. We climbed to 9000 ft, cleared the traffic then returned to 8000 ft. We were out of 8000 ft for about 30 seconds. The TCASII system worked as advertised.

Original NASA ASRS Text

Title: FLC OF A B727 CLBED IN RESPONSE TO A TCASII RA CAUSED BY ANOTHER ACFT VFR 500 FT LOWER.

Narrative: ATC INFORMED US OF VFR TFC AT 7500 FT. OUR ALT WAS 8000 FT, AT NIGHT, IN BROKEN CLOUD CONDITIONS. AS WE CLOSED ON THE TFC, OUR TCASII INDICATED TFC IN YELLOW AND VOICED TFC, TFC. THEN THE TCASII CHANGED FROM YELLOW TO RED WITH A COMMAND OF CLB, CLB. OUR ALT HAD REMAINED AT 8000 FT, AS THE TFC ALT BEGAN TO CHANGE FROM -500 FT TO -400 FT TO -300 FT TO -200 FT IN A MATTER OF SECONDS. I ORDERED A CLB AND ADVISED ATC. WE CLBED TO 9000 FT, CLRED THE TFC THEN RETURNED TO 8000 FT. WE WERE OUT OF 8000 FT FOR ABOUT 30 SECONDS. THE TCASII SYS WORKED AS ADVERTISED.

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.