Pc-12 pilot reported an near midair collision in the pattern at dec.

Attributes
ACN	1292813
Time
Date	201509
Local Time Of Day	0601-1200
Place
Locale Reference	DEC.Airport
State Reference	IL
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	PC-12
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Beechcraft Single Piston Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Person 1
Function	Single Pilot Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 120 Flight Crew Total 9875 Flight Crew Type 690
Events
Anomaly	ATC Issue All Types Conflict NMAC
Miss Distance	Vertical 100

Narrative:

Cmi approach controller cleared me for a visual approach to dec runway 24 at about 5 to 6 miles from dec. He did not turn over communication. I queried him and he turned me over immediately. I was then just 3.5 miles from the field and in dec airspace. A VFR bonanza was on a left downwind turning base right at me. Tower told me to report 3 mile final and I stated already there. My TCAS started stating 'traffic' and I was trying to pick the traffic up visually. I spotted aircraft low and left and knew I could get behind him with a hard left turn. I think we came within 100 feet apart with no or little horizontal.I talked to dec tower manager and they said at the very time I was calling they were receiving a call from cmi about a conflict report on their radar.I had noticed the controller seemed slow in speech rate and seemed to be getting behind the power curve with excess phraseology and no concern for timeliness. I had troubles even reporting on and used a faster speech rate hoping he would pick it up. When talking to the dec tower they said they also were having problems that morning with him being so slow in giving data to them.I do know that the letter of agreement was broken by not turning communication over to dec tower at the point it states.

Original NASA ASRS Text

Title: PC-12 pilot reported an NMAC in the pattern at DEC.

Narrative: CMI approach controller cleared me for a visual approach to DEC Runway 24 at about 5 to 6 miles from DEC. He did not turn over communication. I queried him and he turned me over immediately. I was then just 3.5 miles from the field and in DEC airspace. A VFR Bonanza was on a left downwind turning base right at me. Tower told me to report 3 mile final and I stated already there. My TCAS started stating 'traffic' and I was trying to pick the traffic up visually. I spotted aircraft low and left and knew I could get behind him with a hard left turn. I think we came within 100 feet apart with no or little horizontal.I talked to DEC tower manager and they said at the very time I was calling they were receiving a call from CMI about a conflict report on their radar.I had noticed the controller seemed slow in speech rate and seemed to be getting behind the power curve with excess phraseology and no concern for timeliness. I had troubles even reporting on and used a faster speech rate hoping he would pick it up. When talking to the DEC tower they said they also were having problems that morning with him being so slow in giving data to them.I do know that the letter of agreement was broken by not turning communication over to DEC tower at the point it states.

Data retrieved from NASA's ASRS site 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.