Air carrier has near midair collision with small transport on vectors to approach.

Attributes
ACN	199100
Time
Date	199201
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : sna
State Reference	CA
Altitude	msl bound lower : 4200 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sna
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	climbout : intermediate altitude
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 200
ASRS Report	199100
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 29600 flight time type : 250
ASRS Report	198986
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : nmac other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 100 vertical : 500
Supplementary
Primary Problem	Ambiguous

Narrative:

Aircraft had received vector of 270 degree off the kayoh 2 arrival. Visibility at sna was reported as 5 haze. The reduction in visibility may have been lower as local conditions vary in the los angeles basin. We were vectored across the inbound localizer approach for runway 19R. An medium large transport was pointed out as traffic eastbound being vectored ahead of us. Many targets were indicated on the TCASII. We were directed to turn right to 300 degree and remain level at 5000 ft. The TCASII immediately showed a 'TA' ahead and to the left, low and climbing. Approach issued a further turn to right. The turn was increased slightly to avoid the possible conflict. Coast approach issued a TA for an small transport below and to the left. The TCASII issued a 'RA'. The captain ordered immediate evasive action. I bank further right to approximately 45 degree and lowered the nose as we sharply reduced power. The 'RA' on TCASII terminated and the descent was arrested at approximately 4200 ft. No injuries were reported. Issues: the controller issued his TA much too late in the sequence to reasonably avoid the conflict/near miss. Arrival vectors into sna are habitually too convoluted and lengthy. Excessive maneuvering in crowded airspace only increases exposure to possible traffic conflict. TCASII played a definite role in avoiding a near midair collision.

Original NASA ASRS Text

Title: ACR HAS NMAC WITH SMT ON VECTORS TO APCH.

Narrative: ACFT HAD RECEIVED VECTOR OF 270 DEG OFF THE KAYOH 2 ARR. VISIBILITY AT SNA WAS RPTED AS 5 HAZE. THE REDUCTION IN VISIBILITY MAY HAVE BEEN LOWER AS LCL CONDITIONS VARY IN THE LOS ANGELES BASIN. WE WERE VECTORED ACROSS THE INBOUND LOC APCH FOR RWY 19R. AN MLG WAS POINTED OUT AS TFC EBOUND BEING VECTORED AHEAD OF US. MANY TARGETS WERE INDICATED ON THE TCASII. WE WERE DIRECTED TO TURN R TO 300 DEG AND REMAIN LEVEL AT 5000 FT. THE TCASII IMMEDIATELY SHOWED A 'TA' AHEAD AND TO THE L, LOW AND CLBING. APCH ISSUED A FURTHER TURN TO R. THE TURN WAS INCREASED SLIGHTLY TO AVOID THE POSSIBLE CONFLICT. COAST APCH ISSUED A TA FOR AN SMT BELOW AND TO THE L. THE TCASII ISSUED A 'RA'. THE CAPT ORDERED IMMEDIATE EVASIVE ACTION. I BANK FURTHER R TO APPROX 45 DEG AND LOWERED THE NOSE AS WE SHARPLY REDUCED PWR. THE 'RA' ON TCASII TERMINATED AND THE DSCNT WAS ARRESTED AT APPROX 4200 FT. NO INJURIES WERE RPTED. ISSUES: THE CTLR ISSUED HIS TA MUCH TOO LATE IN THE SEQUENCE TO REASONABLY AVOID THE CONFLICT/NEAR MISS. ARR VECTORS INTO SNA ARE HABITUALLY TOO CONVOLUTED AND LENGTHY. EXCESSIVE MANEUVERING IN CROWDED AIRSPACE ONLY INCREASES EXPOSURE TO POSSIBLE TFC CONFLICT. TCASII PLAYED A DEFINITE ROLE IN AVOIDING A NMAC.

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.