TCASII RA on VFR traffic 500 ft higher head-on caused flight crew to descend 600 ft to clear the RA.

Attributes
ACN	196439
Time
Date	199112
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : lin airport : oak
State Reference	CA
Altitude	msl bound lower : 5400 msl bound upper : 6000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : oak
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 150 flight time total : 7500 flight time type : 400
ASRS Report	196439
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 0 vertical : 1100
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Departed oak and was being radar vectored towards lin, at 6000 MSL on a heading of 060 degree. We experienced a TCASII RA due to traffic, opposite direction, 12 O'clock at 6500 MSL. The TCASII commanded a descent of 2000-2500 FPM down to an altitude of 5400 MSL (600 ft below our assigned altitude) when we were then cleared of the conflict. Bay departure was advised of our TCASII RA, as we climbed back to our assigned altitude of 6000 MSL. There was no subsequent conflict with ATC or other aircraft to our knowledge.

Original NASA ASRS Text

Title: TCASII RA ON VFR TFC 500 FT HIGHER HEAD-ON CAUSED FLC TO DSND 600 FT TO CLR THE RA.

Narrative: DEPARTED OAK AND WAS BEING RADAR VECTORED TOWARDS LIN, AT 6000 MSL ON A HDG OF 060 DEG. WE EXPERIENCED A TCASII RA DUE TO TFC, OPPOSITE DIRECTION, 12 O'CLOCK AT 6500 MSL. THE TCASII COMMANDED A DSCNT OF 2000-2500 FPM DOWN TO AN ALT OF 5400 MSL (600 FT BELOW OUR ASSIGNED ALT) WHEN WE WERE THEN CLRED OF THE CONFLICT. BAY DEP WAS ADVISED OF OUR TCASII RA, AS WE CLBED BACK TO OUR ASSIGNED ALT OF 6000 MSL. THERE WAS NO SUBSEQUENT CONFLICT WITH ATC OR OTHER ACFT TO OUR KNOWLEDGE.

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.