C182 pilot reported an near midair collision with a CJ2.

Attributes
ACN	1647448
Time
Date	201905
Local Time Of Day	1201-1800
Place
Locale Reference	BFL.Airport
State Reference	CA
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	Skylane 182/RG Turbo Skylane/RG
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Aircraft 2
Make Model Name	Citationjet (C525/C526) - CJ I / II / III / IV
Flight Phase	Descent
Route In Use	Vectors
Person 1
Function	Single Pilot
Qualification	Flight Crew Instrument Flight Crew Private
Experience	Flight Crew Last 90 Days 25 Flight Crew Total 850 Flight Crew Type 350
Events
Anomaly	Conflict NMAC Deviation - Procedural Clearance Deviation - Track / Heading All Types
Miss Distance	Vertical 100

Narrative:

We were IFR level at 10;000 ft. We received an alert on the avidyne traffic system; and also on foreflight which was running on an ipad. I advised the controller that we had traffic showing at 9 o'clock near our altitude. She advised us that they were going to pass 1;000 ft below us at 9;000 ft. We showed the aircraft was still at 10;000 ft and getting very close (less than 1/2 mile). At that time we received an alert that showed the other aircraft was at our location and less than 100 ft below. We made an immediate 90 degree turn to the right (north) and climbed. As we were talking; another controller came on and said that the other aircraft was descending. We advised ATC of the diversion and returned to our assigned course when the traffic was past us.upon landing; we were still not sure how close we were. We downloaded the ads-B data from both aircraft and plotted them in excel (we had the call sign from the traffic system and hearing ATC talk to them after). We were chilled to see just how close we had come. The adsb data shows that the CJ2 began a descent; but then briefly leveled off at 10;000 ft (our altitude). Unfortunately this happened just as they were passing our location.

Original NASA ASRS Text

Title: C182 pilot reported an NMAC with a CJ2.

Narrative: We were IFR level at 10;000 ft. We received an alert on the Avidyne Traffic System; and also on Foreflight which was running on an iPad. I advised the controller that we had traffic showing at 9 o'clock near our altitude. She advised us that they were going to pass 1;000 ft below us at 9;000 ft. We showed the aircraft was still at 10;000 ft and getting very close (less than 1/2 mile). At that time we received an alert that showed the other aircraft was at our location and less than 100 ft below. We made an immediate 90 degree turn to the right (North) and climbed. As we were talking; another controller came on and said that the other aircraft was descending. We advised ATC of the diversion and returned to our assigned course when the traffic was past us.Upon landing; we were still not sure how close we were. We downloaded the ADS-B data from both aircraft and plotted them in Excel (we had the call sign from the traffic system and hearing ATC talk to them after). We were chilled to see just how close we had come. The ADSB data shows that the CJ2 began a descent; but then briefly leveled off at 10;000 ft (our altitude). Unfortunately this happened just as they were passing our location.

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.