During descent into isp, approach controller levels air carrier because of unidented traffic observe...

Attributes
ACN	462878
Time
Date	200002
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : isp.airport
State Reference	NY
Altitude	msl bound lower : 2700 msl bound upper : 3000
Environment
Flight Conditions	VMC
Weather Elements	other
Light	Dusk
Aircraft 1
Controlling Facilities	tracon : n90.tracon
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Operating Under FAR Part	Part 121
Flight Phase	descent : vacating altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Flight Phase	climbout : vacating altitude
Flight Plan	None
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 9000
ASRS Report	462878
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne critical conflict : nmac
Independent Detector	aircraft equipment : tcas other controllera other flight crewa
Resolutory Action	controller : issued advisory controller : issued new clearance flight crew : took evasive action
Miss Distance	horizontal : 400 vertical : 100
Supplementary
Problem Areas	Airspace Structure
Primary Problem	Airspace Structure

Narrative:

While being vectored for an ILS to runway 6 at isp, we were cleared by approach to descend from 4000 ft to 2000 ft. While descending through 3000 ft, the controller advised us to stop the descent at 3000 ft because an unidented target had popped up at our 12 O'clock position, range 2 mi, 300 ft below us and climbing. The radio transmission was very hard to understand (scratchy bad transmitter) and the first officer who was the PF did not hear the transmission and continued descending through 3000 ft to 2700 ft. I told him to climb back to 3000 ft. At that time the TCASII displayed the traffic at our 12 O'clock position, 1 mi, 200 ft below us. It gave us an RA climb command and the first officer immediately climbed the aircraft to follow the TCASII command at approximately 4000 FPM. We leveled the aircraft at 4000 ft MSL. The first officer saw the light single pass below us at approximately 100 ft below and 400 ft to our right.

Original NASA ASRS Text

Title: DURING DSCNT INTO ISP, APCH CTLR LEVELS ACR BECAUSE OF UNIDENTED TFC OBSERVED AHEAD.

Narrative: WHILE BEING VECTORED FOR AN ILS TO RWY 6 AT ISP, WE WERE CLRED BY APCH TO DSND FROM 4000 FT TO 2000 FT. WHILE DSNDING THROUGH 3000 FT, THE CTLR ADVISED US TO STOP THE DSCNT AT 3000 FT BECAUSE AN UNIDENTED TARGET HAD POPPED UP AT OUR 12 O'CLOCK POS, RANGE 2 MI, 300 FT BELOW US AND CLBING. THE RADIO XMISSION WAS VERY HARD TO UNDERSTAND (SCRATCHY BAD XMITTER) AND THE FO WHO WAS THE PF DID NOT HEAR THE XMISSION AND CONTINUED DSNDING THROUGH 3000 FT TO 2700 FT. I TOLD HIM TO CLB BACK TO 3000 FT. AT THAT TIME THE TCASII DISPLAYED THE TFC AT OUR 12 O'CLOCK POS, 1 MI, 200 FT BELOW US. IT GAVE US AN RA CLB COMMAND AND THE FO IMMEDIATELY CLBED THE ACFT TO FOLLOW THE TCASII COMMAND AT APPROX 4000 FPM. WE LEVELED THE ACFT AT 4000 FT MSL. THE FO SAW THE LIGHT SINGLE PASS BELOW US AT APPROX 100 FT BELOW AND 400 FT TO OUR R.

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.

During descent into isp, approach controller levels air carrier because of unidented traffic observed ahead.