Flight crew of large transport descended below assigned altitude in response to a TCASII RA.

Attributes
ACN	277069
Time
Date	199407
Day	Thu
Place
Locale Reference	atc facility : swf
State Reference	NY
Altitude	msl bound lower : 10500 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B727-200
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute airway : zbw
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	climbout : intermediate altitude
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	277069
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance other anomaly other
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

In the vicinity of briss intersection while on radar vectors, we experienced a TCASII TA followed by an RA which was followed by us. The intruder aircraft was initially noticed on the TCASII at approximately 1 O'clock and 10 mi and 500 ft below us. We were at 11000 ft and level. Approximately 5 to 6 mi from our aircraft, the TCASII issued a TA. It then issued an RA very shortly thereafter, which we followed. The intruder aircraft was climbing and eventually passed behind and above us. We had descended 500 ft below our cleared altitude (11000 ft) and, once the clear of conflict was issued, we climbed back up to 11000 ft in accordance with ATC instructions.

Original NASA ASRS Text

Title: FLC OF LGT DSNDED BELOW ASSIGNED ALT IN RESPONSE TO A TCASII RA.

Narrative: IN THE VICINITY OF BRISS INTXN WHILE ON RADAR VECTORS, WE EXPERIENCED A TCASII TA FOLLOWED BY AN RA WHICH WAS FOLLOWED BY US. THE INTRUDER ACFT WAS INITIALLY NOTICED ON THE TCASII AT APPROX 1 O'CLOCK AND 10 MI AND 500 FT BELOW US. WE WERE AT 11000 FT AND LEVEL. APPROX 5 TO 6 MI FROM OUR ACFT, THE TCASII ISSUED A TA. IT THEN ISSUED AN RA VERY SHORTLY THEREAFTER, WHICH WE FOLLOWED. THE INTRUDER ACFT WAS CLBING AND EVENTUALLY PASSED BEHIND AND ABOVE US. WE HAD DSNDED 500 FT BELOW OUR CLRED ALT (11000 FT) AND, ONCE THE CLR OF CONFLICT WAS ISSUED, WE CLBED BACK UP TO 11000 FT IN ACCORDANCE WITH ATC INSTRUCTIONS.

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.