A potential conflict on air carrier departure in proximity of arsa.

Attributes
ACN	200583
Time
Date	199201
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ont
State Reference	CA
Altitude	msl bound lower : 5200 msl bound upper : 5500
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	climbout : intermediate altitude cruise other
Route In Use	departure other departure sid : sid
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Aircraft
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 11500 flight time type : 1000
ASRS Report	200583
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe non adherence : far other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance flight crew : took evasive action other
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 250
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other
Situations
ATC Facility	procedure or policy : unspecified

Narrative:

Departed ont on the pomona 6 departure. In the turn from 255 degree heading to intercept the pom 114 degree radial, departure control issued a TA that was smeared by a simultaneous transmission from a VFR aircraft (departure was handling several VFR aircraft). The following occurred within 8 to 10 seconds total: climbing through 5000 ft at 2500 FPM departure called VFR traffic at 5500 ft, 12 O'clock 1-2 mi, 'maintain '5' if you don't see him.' TCASII sounded a traffic alert; ascent was stopped at 5200 ft; TCASII commanded a RA of descend at a min of 2500 FPM, an abrupt descent was initiated. TCASII continued the descend command at 2500 FPM or more as we passed the 5000 ATC clearance limit. We elected to follow the TCASII commands to descend until a 'clear of conflict' annunciation at 4600 ft. We had never visually seen the traffic and ATC reported that no loss of separation had occurred. Contributing factors to the event were interrupted communications between us and departure control due to too many VFR aircraft on the frequency seeking advisories.

Original NASA ASRS Text

Title: A POTENTIAL CONFLICT ON ACR DEP IN PROX OF ARSA.

Narrative: DEPARTED ONT ON THE POMONA 6 DEP. IN THE TURN FROM 255 DEG HDG TO INTERCEPT THE POM 114 DEG RADIAL, DEP CTL ISSUED A TA THAT WAS SMEARED BY A SIMULTANEOUS XMISSION FROM A VFR ACFT (DEP WAS HANDLING SEVERAL VFR ACFT). THE FOLLOWING OCCURRED WITHIN 8 TO 10 SECONDS TOTAL: CLBING THROUGH 5000 FT AT 2500 FPM DEP CALLED VFR TFC AT 5500 FT, 12 O'CLOCK 1-2 MI, 'MAINTAIN '5' IF YOU DON'T SEE HIM.' TCASII SOUNDED A TFC ALERT; ASCENT WAS STOPPED AT 5200 FT; TCASII COMMANDED A RA OF DSND AT A MIN OF 2500 FPM, AN ABRUPT DSCNT WAS INITIATED. TCASII CONTINUED THE DSND COMMAND AT 2500 FPM OR MORE AS WE PASSED THE 5000 ATC CLRNC LIMIT. WE ELECTED TO FOLLOW THE TCASII COMMANDS TO DSND UNTIL A 'CLR OF CONFLICT' ANNUNCIATION AT 4600 FT. WE HAD NEVER VISUALLY SEEN THE TFC AND ATC RPTED THAT NO LOSS OF SEPARATION HAD OCCURRED. CONTRIBUTING FACTORS TO THE EVENT WERE INTERRUPTED COMS BTWN US AND DEP CTL DUE TO TOO MANY VFR ACFT ON THE FREQ SEEKING ADVISORIES.

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.