Air carrier mdt altitude deviation excursion from clearance altitude in response to TCASII RA.

Attributes
ACN	180554
Time
Date	199106
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : hpn
State Reference	NY
Altitude	msl bound lower : 1500 msl bound upper : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90
Operator	common carrier : air carrier
Make Model Name	Medium Transport, High Wing, 2 Turboprop Eng
Flight Phase	descent other other
Route In Use	enroute : on vectors
Flight Plan	IFR
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 : 5000 flight time type : 1000
ASRS Report	180554
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
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	horizontal : 2000 vertical : 100
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

Flight was on an initial heading in the approach phase to runway 34 at hpn. ATC called traffic at 9 O'clock and there was no visibility contact. ATC then gave us a turn to 090 degrees. As the aircraft was in the turn, crew received a TA. Shortly after, an RA was received, followed by a TCAS 'descend now' instruction. As the aircraft began the descent, crew notified ATC of evasive action. TCAS required a 1500-2000 FPM descent rate. Aircraft descended to 1500' AGL and immediately returned to 2000' MSL with notification to ATC. ATC then gave us a new heading and 2000' assigned altitude. Flight proceeded to hpn west/O further incident. The controller advised the crew that they were not in radio contact with the traffic. After discussing the incident, the crew concluded that the controller's turn should probably have been rejected based on TCAS information. However, the TCAS alert (TA) did not occur until the turn had begun. Also concluded that the TCAS was a very valuable addition to the cockpit.

Original NASA ASRS Text

Title: ACR MDT ALT DEVIATION EXCURSION FROM CLRNC ALT IN RESPONSE TO TCASII RA.

Narrative: FLT WAS ON AN INITIAL HDG IN THE APCH PHASE TO RWY 34 AT HPN. ATC CALLED TFC AT 9 O'CLOCK AND THERE WAS NO VIS CONTACT. ATC THEN GAVE US A TURN TO 090 DEGS. AS THE ACFT WAS IN THE TURN, CREW RECEIVED A TA. SHORTLY AFTER, AN RA WAS RECEIVED, FOLLOWED BY A TCAS 'DSND NOW' INSTRUCTION. AS THE ACFT BEGAN THE DSNT, CREW NOTIFIED ATC OF EVASIVE ACTION. TCAS REQUIRED A 1500-2000 FPM DSNT RATE. ACFT DSNDED TO 1500' AGL AND IMMEDIATELY RETURNED TO 2000' MSL WITH NOTIFICATION TO ATC. ATC THEN GAVE US A NEW HDG AND 2000' ASSIGNED ALT. FLT PROCEEDED TO HPN W/O FURTHER INCIDENT. THE CTLR ADVISED THE CREW THAT THEY WERE NOT IN RADIO CONTACT WITH THE TFC. AFTER DISCUSSING THE INCIDENT, THE CREW CONCLUDED THAT THE CTLR'S TURN SHOULD PROBABLY HAVE BEEN REJECTED BASED ON TCAS INFO. HOWEVER, THE TCAS ALERT (TA) DID NOT OCCUR UNTIL THE TURN HAD BEGUN. ALSO CONCLUDED THAT THE TCAS WAS A VERY VALUABLE ADDITION TO THE COCKPIT.

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.