Air carrier medium large transport altitude deviation in response to TCASII RA.

Attributes
ACN	185019
Time
Date	199107
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : sau
State Reference	CA
Altitude	msl bound lower : 6000 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
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 descent other
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	descent other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi pilot : commercial pilot : flight engineer
Experience	flight time last 90 days : 185 flight time total : 18000 flight time type : 1050
ASRS Report	185019
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 210 flight time total : 6000 flight time type : 800
ASRS Report	185022
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 12000
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

ATC called descending traffic at 11 O'clock 8 mi, same direction of flight. While looking for that traffic, a TCAS RA 'descend' was received for 2 O'clock traffic. We were at 7000 ft MSL and started a descent, following TCAS guidelines. We called ATC leaving 7000 ft. Passing through 6700 ft and level at 6000 ft a VFR small transport was spotted 2 mi off our right wing which agreed with our TCAS information. ATC advised that the original call was for 1 O'clock traffic, which he called, and reclred us to sausalito VOR at 6000 ft. Although ATC had given us advisory and clearance to pass the traffic, I feel the TCAS system worked very well. The other airplane was an small transport descending from 7500 ft to 5500 ft MSL. Since either the controller misstated the original direction of traffic or we misheard it, we were looking for both 11 O'clock and 2 O'clock TCAS traffic. Regardless of other factors, the TCAS RA was timely and correctly kept us separated from the small transport traffic.

Original NASA ASRS Text

Title: ACR MLG ALT DEV IN RESPONSE TO TCASII RA.

Narrative: ATC CALLED DSNDING TFC AT 11 O'CLOCK 8 MI, SAME DIRECTION OF FLT. WHILE LOOKING FOR THAT TFC, A TCAS RA 'DSND' WAS RECEIVED FOR 2 O'CLOCK TFC. WE WERE AT 7000 FT MSL AND STARTED A DSCNT, FOLLOWING TCAS GUIDELINES. WE CALLED ATC LEAVING 7000 FT. PASSING THROUGH 6700 FT AND LEVEL AT 6000 FT A VFR SMT WAS SPOTTED 2 MI OFF OUR R WING WHICH AGREED WITH OUR TCAS INFO. ATC ADVISED THAT THE ORIGINAL CALL WAS FOR 1 O'CLOCK TFC, WHICH HE CALLED, AND RECLRED US TO SAUSALITO VOR AT 6000 FT. ALTHOUGH ATC HAD GIVEN US ADVISORY AND CLRNC TO PASS THE TFC, I FEEL THE TCAS SYS WORKED VERY WELL. THE OTHER AIRPLANE WAS AN SMT DSNDING FROM 7500 FT TO 5500 FT MSL. SINCE EITHER THE CTLR MISSTATED THE ORIGINAL DIRECTION OF TFC OR WE MISHEARD IT, WE WERE LOOKING FOR BOTH 11 O'CLOCK AND 2 O'CLOCK TCAS TFC. REGARDLESS OF OTHER FACTORS, THE TCAS RA WAS TIMELY AND CORRECTLY KEPT US SEPARATED FROM THE SMT TFC.

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.