TCASII compliance causes altitude deviation.

Attributes
ACN	178265
Time
Date	199105
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : vcn
State Reference	NJ
Altitude	msl bound lower : 9500 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc tower : hou
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer pilot : cfi
Experience	flight time last 90 days : 180 flight time total : 8200 flight time type : 1200
ASRS Report	178265
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	horizontal : 9000 vertical : 1000
Supplementary
Air Traffic Incident	other

Narrative:

TCAS RA commanded a descent with traffic at 11-12 O'clock, +400'. We descended from level flight at 10000' to 9500', at which time we visually located traffic passing our 9 O'clock position. We advised ATC of our altitude deviation and returned to 10000' west/O further incident.

Original NASA ASRS Text

Title: TCASII COMPLIANCE CAUSES ALT DEVIATION.

Narrative: TCAS RA COMMANDED A DSNT WITH TFC AT 11-12 O'CLOCK, +400'. WE DSNDED FROM LEVEL FLT AT 10000' TO 9500', AT WHICH TIME WE VISUALLY LOCATED TFC PASSING OUR 9 O'CLOCK POS. WE ADVISED ATC OF OUR ALT DEVIATION AND RETURNED TO 10000' W/O FURTHER INCIDENT.

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.