Crj-700 captain reported a near midair collision while descending in the vicinity of bhm.

Attributes
ACN	1412773
Time
Date	201612
Local Time Of Day	0601-1200
Place
Locale Reference	BHM.Airport
State Reference	AL
Environment
Light	Daylight
Aircraft 1
Make Model Name	Regional Jet 700 ER/LR (CRJ700)
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Person 1
Function	Captain Pilot Not Flying Check Pilot
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Conflict NMAC

Narrative:

We were descending to 5000 ft per ATC instruction. We noticed a target on TCAS in our vicinity. At that same moment ATC told us to maintain 6000 ft; we were already at 5800. The student in the right seat was the PF; but he hesitated due to his confusion with the automation. I took control of the aircraft; disengaged the autopilot; and initiated an aggressive climb. We climbed back up to 6600 ft before leveling off and then; once composed; descended back to 6000 ft. At one point the TCAS indicated we were within 100 ft of the other aircraft.

Original NASA ASRS Text

Title: CRJ-700 Captain reported a NMAC while descending in the vicinity of BHM.

Narrative: We were descending to 5000 ft per ATC instruction. We noticed a target on TCAS in our vicinity. At that same moment ATC told us to maintain 6000 ft; we were already at 5800. The student in the right seat was the PF; but he hesitated due to his confusion with the automation. I took control of the aircraft; disengaged the autopilot; and initiated an aggressive climb. We climbed back up to 6600 ft before leveling off and then; once composed; descended back to 6000 ft. At one point the TCAS indicated we were within 100 ft of the other aircraft.

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.