Pc-12 pilot reported an airborne conflict with a light aircraft shortly after takeoff from bjc.

Attributes
ACN	1491470
Time
Date	201710
Local Time Of Day	1201-1800
Place
Locale Reference	BJC.Airport
State Reference	CO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	PC-12
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	M-20 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 50 Flight Crew Total 10800 Flight Crew Type 7600
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy
Miss Distance	Horizontal 500 Vertical 100

Narrative:

IFR departure clearance off bjc 12L [and I] was flying heading 150 and climbing to 8000. After liftoff tower advised traffic in a left downwind for 12R (mooney). There was conversation with an additional mooney inbound to the airport. We could not make a right turn to 150 because of the traffic on downwind initially. When we were clear of conflict with that aircraft (just past abeam their position) we began our turn and got a TA. I looked down to see if the conflict was with the downwind traffic. As soon as I looked back up the other mooney was crossing our flight path. There was minimal separation. I increased the rate of turn and increased the rate of climb to de-conflict our aircraft. This occurred less than 1 nm from the departure end of runway 12L. I did not hear us called out as traffic for the other aircraft. I do not know if the inbound aircraft was going to the wrong runway or if there was a loss of positional awareness in the tower when our takeoff clearance was issued. If we had delayed our takeoff by 30-60 seconds neither of the other aircraft would have been an issue for our takeoff instructions.

Original NASA ASRS Text

Title: PC-12 pilot reported an airborne conflict with a light aircraft shortly after takeoff from BJC.

Narrative: IFR departure clearance off BJC 12L [and I] was flying heading 150 and climbing to 8000. After liftoff Tower advised traffic in a left downwind for 12R (Mooney). There was conversation with an additional Mooney inbound to the airport. We could not make a right turn to 150 because of the traffic on downwind initially. When we were clear of conflict with that aircraft (just past abeam their position) we began our turn and got a TA. I looked down to see if the conflict was with the downwind traffic. As soon as I looked back up the other Mooney was crossing our flight path. There was minimal separation. I increased the rate of turn and increased the rate of climb to de-conflict our aircraft. This occurred less than 1 nm from the departure end of runway 12L. I did not hear us called out as traffic for the other aircraft. I do not know if the inbound aircraft was going to the wrong runway or if there was a loss of positional awareness in the Tower when our takeoff clearance was issued. If we had delayed our takeoff by 30-60 seconds neither of the other aircraft would have been an issue for our takeoff instructions.

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.