Air carrier medium large transport altitude deviation excursion from clearance altitude in response ...

Attributes
ACN	194614
Time
Date	199111
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : sna
State Reference	CA
Altitude	msl bound lower : 10000 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ont
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : commercial pilot : atp
Experience	flight time last 90 days : 75 flight time total : 10500
ASRS Report	194614
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 4500 vertical : 1200
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While we were level at 10000 MSL, ATC advised of an small aircraft, 12 O'clock, opposite direction at either 8800 MSL or 9800 MSL (not sure). The small aircraft had reported us in sight. TCASII gave us an RA calling for a min of a 2000 FPM climb which we did to 11000 MSL. It showed the small aircraft at 9800 MSL, 12 O'clock, 2 mi. When we reached 11000 MSL, a few seconds later, we saw the small aircraft at 3 O'clock about 1200 ft lower as the TCASII displayed. Had we stayed at 10000 we believe separation would have been 200 ft vertically and about 3/4 mi horizontally. We then descended to 8000 (new clearance) and no other action was taken.

Original NASA ASRS Text

Title: ACR MLG ALTDEV EXCURSION FROM CLRNC ALT IN RESPONSE TO TCASII RA.

Narrative: WHILE WE WERE LEVEL AT 10000 MSL, ATC ADVISED OF AN SMA, 12 O'CLOCK, OPPOSITE DIRECTION AT EITHER 8800 MSL OR 9800 MSL (NOT SURE). THE SMA HAD RPTED US IN SIGHT. TCASII GAVE US AN RA CALLING FOR A MIN OF A 2000 FPM CLB WHICH WE DID TO 11000 MSL. IT SHOWED THE SMA AT 9800 MSL, 12 O'CLOCK, 2 MI. WHEN WE REACHED 11000 MSL, A FEW SECONDS LATER, WE SAW THE SMA AT 3 O'CLOCK ABOUT 1200 FT LOWER AS THE TCASII DISPLAYED. HAD WE STAYED AT 10000 WE BELIEVE SEPARATION WOULD HAVE BEEN 200 FT VERTICALLY AND ABOUT 3/4 MI HORIZLY. WE THEN DSNDED TO 8000 (NEW CLRNC) AND NO OTHER ACTION WAS TAKEN.

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.

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