Medium large transport alerted to traffic but no visual contact. TCASII RA given.

Attributes
ACN	204205
Time
Date	199203
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : sna
State Reference	CA
Altitude	msl bound lower : 5000 msl bound upper : 5600
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 : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 6200 flight time type : 200
ASRS Report	204205
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : atp pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	horizontal : 1500 vertical : 500
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

At 5000 ft on a heading of 020 degree, speed 250 KTS, on vectors to final approach for a landing at sna (runway 19R), coast approach alerted us to traffic at our 1-2 O'clock position. Although visual contact could not be made the traffic (a small, light aircraft traveling on an approximately heading of 260 degree up the coast line) was seen on the TCASII screen, which indicated the traffic was only 300 ft below and crossing our path. TCASII warned of the traffic and commanded an immediate climb as indicated on the vsi. Because visual contact had not been made we initiated a climb, alerted coast approach of our climb to avoid traffic and comply with the TCASII command. Soon after initiating the climb visual contact was made, we leveled at 5600 ft and then descended back to 5000 ft.

Original NASA ASRS Text

Title: MLG ALERTED TO TFC BUT NO VISUAL CONTACT. TCASII RA GIVEN.

Narrative: AT 5000 FT ON A HDG OF 020 DEG, SPD 250 KTS, ON VECTORS TO FINAL APCH FOR A LNDG AT SNA (RWY 19R), COAST APCH ALERTED US TO TFC AT OUR 1-2 O'CLOCK POS. ALTHOUGH VISUAL CONTACT COULD NOT BE MADE THE TFC (A SMALL, LIGHT ACFT TRAVELING ON AN APPROX HDG OF 260 DEG UP THE COAST LINE) WAS SEEN ON THE TCASII SCREEN, WHICH INDICATED THE TFC WAS ONLY 300 FT BELOW AND XING OUR PATH. TCASII WARNED OF THE TFC AND COMMANDED AN IMMEDIATE CLB AS INDICATED ON THE VSI. BECAUSE VISUAL CONTACT HAD NOT BEEN MADE WE INITIATED A CLB, ALERTED COAST APCH OF OUR CLB TO AVOID TFC AND COMPLY WITH THE TCASII COMMAND. SOON AFTER INITIATING THE CLB VISUAL CONTACT WAS MADE, WE LEVELED AT 5600 FT AND THEN DSNDED BACK TO 5000 FT.

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.