A crj pilot on descent into jax had an near midair collision with a mooney.

Attributes
ACN	749482
Time
Date	200708
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : jax.airport
State Reference	FL
Altitude	msl single value : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : jax.tracon
Operator	common carrier : air carrier
Make Model Name	Regional Jet 200 ER&LR
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : n/s
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : jax.tracon
Operator	general aviation : personal
Make Model Name	M-20 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 250 flight time total : 10000 flight time type : 4000
ASRS Report	749482
Events
Anomaly	conflict : nmac
Independent Detector	aircraft equipment : tcas
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 0 vertical : 400
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

I complied with all ATC instructions. I descended to 10000 ft. We were advised of traffic at 9000 ft and 9500 ft but were not aware of their direction of flight. Our TCAS display showed closure when the other aircraft symbol turned solid blue. The approach controller advised the mooney that traffic was a crj (us) passing overhead 500 ft; our TCAS was turning yellow 'traffic traffic.' there was too much chatter to get a turn or change in altitude. When other aircraft turned red and we got RA I had already disconnected autoplt and added thrust to begin deviation. At RA I climbed immediately. Why do controllers think 500 ft of 'clearance' is enough?

Original NASA ASRS Text

Title: A CRJ PILOT ON DESCENT INTO JAX HAD AN NMAC WITH A MOONEY.

Narrative: I COMPLIED WITH ALL ATC INSTRUCTIONS. I DSNDED TO 10000 FT. WE WERE ADVISED OF TFC AT 9000 FT AND 9500 FT BUT WERE NOT AWARE OF THEIR DIRECTION OF FLT. OUR TCAS DISPLAY SHOWED CLOSURE WHEN THE OTHER ACFT SYMBOL TURNED SOLID BLUE. THE APCH CTLR ADVISED THE MOONEY THAT TFC WAS A CRJ (US) PASSING OVERHEAD 500 FT; OUR TCAS WAS TURNING YELLOW 'TFC TFC.' THERE WAS TOO MUCH CHATTER TO GET A TURN OR CHANGE IN ALT. WHEN OTHER ACFT TURNED RED AND WE GOT RA I HAD ALREADY DISCONNECTED AUTOPLT AND ADDED THRUST TO BEGIN DEV. AT RA I CLBED IMMEDIATELY. WHY DO CTLRS THINK 500 FT OF 'CLRNC' IS ENOUGH?

Data retrieved from NASA's ASRS site as of January 2009 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.