BE1900 flight crew has near midair collision during descent into mia.

Attributes
ACN	557136
Time
Date	200208
Day	Fri
Local Time Of Day	1201 To 1800
Place
State Reference	FO
Altitude	msl single value : 4000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zma.artcc tracon : mia.tracon
Operator	common carrier : air taxi
Make Model Name	Beech 1900
Operating Under FAR Part	Part 135
Flight Phase	cruise : level descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : mia.tracon
Make Model Name	Twin Otter DHC-6
Flight Phase	descent : intermediate altitude
Route In Use	enroute other
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 280 flight time total : 3500 flight time type : 2600
ASRS Report	557136
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : nmac inflight encounter : weather non adherence : far
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 200 vertical : 100
Supplementary
Problem Areas	Weather Environmental Factor ATC Human Performance Airspace Structure
Primary Problem	ATC Human Performance

Narrative:

We were on our descent, tracking the airway between vors. ZMA instructed us to cross dekac intersection at 4000 ft. Prior to dekac, we were level at 4000 ft, we were then handed off to approach. I had the TCASII on the 10 mi ring. I noticed a target at 500 ft above us, approximately 6 mi or so. I was not sure of the aircraft's direction of flight. We were wbound. To avoid a collision with the aircraft, we banked 30 degrees and changed heading. I advised mia approach that I had an aircraft on our TCASII and was deviating to avoid a collision. At that point, I could see an aircraft emerge from a climb off our port wing. The aircraft was what I approximated to be 200 ft away, and would have, I am sure, collided with us, if not for actions. I could see this aircraft was a white DH6 twin otter with red and blue trim. I asked ATC why we were not advised of the aircraft. He told me that he was on the land line phone, and did not see the other aircraft until I requested deviation. I later asked him for a phone number to speak with his supervisor. After landing, I called the TRACON and spoke with the operations suvr. He also told me that the controller was distracted by his phone and other aircraft. He also said that the unknown aircraft was not talking to anyone and was VFR, but was not flying a VFR altitude.

Original NASA ASRS Text

Title: BE1900 FLC HAS NMAC DURING DSCNT INTO MIA.

Narrative: WE WERE ON OUR DSCNT, TRACKING THE AIRWAY BTWN VORS. ZMA INSTRUCTED US TO CROSS DEKAC INTXN AT 4000 FT. PRIOR TO DEKAC, WE WERE LEVEL AT 4000 FT, WE WERE THEN HANDED OFF TO APCH. I HAD THE TCASII ON THE 10 MI RING. I NOTICED A TARGET AT 500 FT ABOVE US, APPROX 6 MI OR SO. I WAS NOT SURE OF THE ACFT'S DIRECTION OF FLT. WE WERE WBOUND. TO AVOID A COLLISION WITH THE ACFT, WE BANKED 30 DEGS AND CHANGED HEADING. I ADVISED MIA APCH THAT I HAD AN ACFT ON OUR TCASII AND WAS DEVIATING TO AVOID A COLLISION. AT THAT POINT, I COULD SEE AN ACFT EMERGE FROM A CLB OFF OUR PORT WING. THE ACFT WAS WHAT I APPROXIMATED TO BE 200 FT AWAY, AND WOULD HAVE, I AM SURE, COLLIDED WITH US, IF NOT FOR ACTIONS. I COULD SEE THIS ACFT WAS A WHITE DH6 TWIN OTTER WITH RED AND BLUE TRIM. I ASKED ATC WHY WE WERE NOT ADVISED OF THE ACFT. HE TOLD ME THAT HE WAS ON THE LAND LINE PHONE, AND DID NOT SEE THE OTHER ACFT UNTIL I REQUESTED DEV. I LATER ASKED HIM FOR A PHONE NUMBER TO SPEAK WITH HIS SUPVR. AFTER LNDG, I CALLED THE TRACON AND SPOKE WITH THE OPS SUVR. HE ALSO TOLD ME THAT THE CTLR WAS DISTRACTED BY HIS PHONE AND OTHER ACFT. HE ALSO SAID THAT THE UNKNOWN ACFT WAS NOT TALKING TO ANYONE AND WAS VFR, BUT WAS NOT FLYING A VFR ALT.

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.