Air carrier pilot takes evasive action in response to TCASII RA.

Attributes
ACN	437776
Time
Date	199905
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : bwz.vor
State Reference	NJ
Altitude	msl single value : 6000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90.tracon tower : pdx.tower
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : n90.tracon
Operator	Other
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	cruise : level
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 180 flight time total : 17000 flight time type : 11000
ASRS Report	437776
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : multi engine
Events
Anomaly	conflict : airborne critical
Independent Detector	aircraft equipment : tcas
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 500 vertical : 500
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	Ambiguous

Narrative:

TCASII TA at 6000 ft followed by RA to 'descend' 8-10 seconds later. Evasive action was taken and small aircraft passed over us at 6000 ft. This would have been a very dangerous incident without the TCASII system. New york approach gave no radar advisories and apparently did not know of other plane's presence.

Original NASA ASRS Text

Title: ACR PLT TAKES EVASIVE ACTION IN RESPONSE TO TCASII RA.

Narrative: TCASII TA AT 6000 FT FOLLOWED BY RA TO 'DSND' 8-10 SECONDS LATER. EVASIVE ACTION WAS TAKEN AND SMALL ACFT PASSED OVER US AT 6000 FT. THIS WOULD HAVE BEEN A VERY DANGEROUS INCIDENT WITHOUT THE TCASII SYS. NEW YORK APCH GAVE NO RADAR ADVISORIES AND APPARENTLY DID NOT KNOW OF OTHER PLANE'S PRESENCE.

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.