DH8 flight crew responds to TCASII RA while on approach to hpn.

Attributes
ACN	442483
Time
Date	199907
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : hpn.airport
State Reference	NY
Altitude	msl bound lower : 2000 msl bound upper : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : hpn.tower
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 34
Flight Phase	descent : approach
Route In Use	approach : charted visual
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tower : hpn.tower
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi pilot : commercial pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 300 flight time total : 16000 flight time type : 3800
ASRS Report	442483
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac conflict : airborne critical non adherence : required legal separation other anomaly other
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	controller : issued advisory flight crew : returned to assigned altitude flight crew : took evasive action
Miss Distance	horizontal : 0 vertical : 250
Supplementary
Problem Areas	Flight Crew Human Performance Airspace Structure ATC Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

On approach into westchester county airport, we had been cleared for the sound visual runway 34 approach at 2000 ft and new york approach control had turned us over to westchester tower. On check-in, the tower asked us to slow to approach speed while on the base leg. I slowed the aircraft to 120 KIAS and configured the aircraft with gear down and flaps 15 degrees. At 7 NM on final, we got a TCASII RA warning with climb instructions with no TCASII TA or tower advisory warning. We started a climb of between 1000-1500 FPM. The first officer advised the tower of the RA and deviation. The tower replied that he had an aircraft at 1700 ft below us. The TCASII warning stopped and we got a TCASII clear message at approximately 2300 ft. I leveled at 2500 ft and continued the approach. I did not see the other aircraft, nor did I notice the altitude separation message on the TCASII. The RA was slightly right and forward of our position on the TCASII indicator (probably less than 1/2 mi). I estimate that the separation was less than 300 ft.

Original NASA ASRS Text

Title: DH8 FLC RESPONDS TO TCASII RA WHILE ON APCH TO HPN.

Narrative: ON APCH INTO WESTCHESTER COUNTY ARPT, WE HAD BEEN CLRED FOR THE SOUND VISUAL RWY 34 APCH AT 2000 FT AND NEW YORK APCH CTL HAD TURNED US OVER TO WESTCHESTER TWR. ON CHK-IN, THE TWR ASKED US TO SLOW TO APCH SPD WHILE ON THE BASE LEG. I SLOWED THE ACFT TO 120 KIAS AND CONFIGURED THE ACFT WITH GEAR DOWN AND FLAPS 15 DEGS. AT 7 NM ON FINAL, WE GOT A TCASII RA WARNING WITH CLB INSTRUCTIONS WITH NO TCASII TA OR TWR ADVISORY WARNING. WE STARTED A CLB OF BTWN 1000-1500 FPM. THE FO ADVISED THE TWR OF THE RA AND DEV. THE TWR REPLIED THAT HE HAD AN ACFT AT 1700 FT BELOW US. THE TCASII WARNING STOPPED AND WE GOT A TCASII CLR MESSAGE AT APPROX 2300 FT. I LEVELED AT 2500 FT AND CONTINUED THE APCH. I DID NOT SEE THE OTHER ACFT, NOR DID I NOTICE THE ALT SEPARATION MESSAGE ON THE TCASII. THE RA WAS SLIGHTLY R AND FORWARD OF OUR POS ON THE TCASII INDICATOR (PROBABLY LESS THAN 1/2 MI). I ESTIMATE THAT THE SEPARATION WAS LESS THAN 300 FT.

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.