Potential conflict avoided by the TCASII RA.

Attributes
ACN	274118
Time
Date	199406
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : sna
State Reference	CA
Altitude	msl bound lower : 8000 msl bound upper : 14000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	approach : visual
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
ASRS Report	274118
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other
Situations
ATC Facility	procedure or policy : unspecified

Narrative:

At about XA00 hours we were descending to 14000 ft from the east on approach to sna. Traffic ahead was below us and we were asked to call him in sight. When we did, we were told to descend to 8000 ft. After we passed through 14000 ft the TCASII told us to descend and although the collision course was not so apparent due to the other aircraft's small size and our pitch down attitude, the TCASII position and altitude helped us determine to hasten our descent with speed brakes. This was not enough so we pushed the nose farther down to avoid the small aircraft. This, in my opinion, was very evasive and totally inappropriate for ATC to have allowed, given we were both being controled. After all, are we not on an IFR flight plan and don't our passenger expect safe separation. When ATC gives us a descent clearance and then tells us to maintain visual separation, do they then have no responsibility for our safety. This was too close and it seems the term maintain visual separation is used too often and unsafely. The captain believed a report was unnecessary, but I'm going to be around a lot longer than him and I don't want to see this trend of unsafe procedures to continue to the point of accident occurrence, especially with me on board.

Original NASA ASRS Text

Title: POTENTIAL CONFLICT AVOIDED BY THE TCASII RA.

Narrative: AT ABOUT XA00 HRS WE WERE DSNDING TO 14000 FT FROM THE E ON APCH TO SNA. TFC AHEAD WAS BELOW US AND WE WERE ASKED TO CALL HIM IN SIGHT. WHEN WE DID, WE WERE TOLD TO DSND TO 8000 FT. AFTER WE PASSED THROUGH 14000 FT THE TCASII TOLD US TO DSND AND ALTHOUGH THE COLLISION COURSE WAS NOT SO APPARENT DUE TO THE OTHER ACFT'S SMALL SIZE AND OUR PITCH DOWN ATTITUDE, THE TCASII POS AND ALT HELPED US DETERMINE TO HASTEN OUR DSCNT WITH SPD BRAKES. THIS WAS NOT ENOUGH SO WE PUSHED THE NOSE FARTHER DOWN TO AVOID THE SMALL ACFT. THIS, IN MY OPINION, WAS VERY EVASIVE AND TOTALLY INAPPROPRIATE FOR ATC TO HAVE ALLOWED, GIVEN WE WERE BOTH BEING CTLED. AFTER ALL, ARE WE NOT ON AN IFR FLT PLAN AND DON'T OUR PAX EXPECT SAFE SEPARATION. WHEN ATC GIVES US A DSCNT CLRNC AND THEN TELLS US TO MAINTAIN VISUAL SEPARATION, DO THEY THEN HAVE NO RESPONSIBILITY FOR OUR SAFETY. THIS WAS TOO CLOSE AND IT SEEMS THE TERM MAINTAIN VISUAL SEPARATION IS USED TOO OFTEN AND UNSAFELY. THE CAPT BELIEVED A RPT WAS UNNECESSARY, BUT I'M GOING TO BE AROUND A LOT LONGER THAN HIM AND I DON'T WANT TO SEE THIS TREND OF UNSAFE PROCS TO CONTINUE TO THE POINT OF ACCIDENT OCCURRENCE, ESPECIALLY WITH ME ON BOARD.

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.