TRACON controller providing OJT described a loss of separation event during attempts to vector aircr...

Narrative:

I was providing instruction on the north final to runway 26R. We were doing visual approaches; but had to get the aircraft down and close due to clouds and visibility. The developmental was working a situation closer to the airport with a few airplanes trying to keep them separated. The CRJ2 came over slightly high and fast; so with the cloud base at about 6;300 MSL; we had to get the aircraft down to get the airport or proceeding aircraft insight. The B717 was inbound to runway 27L; and had not seen the airport yet and was turning into final at 7;000 ft. Timely action was not taken to put the CRJ2 into a place to do anything with him; so my developmental was going to try and turn the aircraft toward the airport; but I instructed him to turn him to the left to pass behind the B717. Since I was providing this information; it was not done in a timely manner; and the two aircraft loss separation. Make sure that my developmental had a plan to work the aircraft into a position and altitude that would work him into the sequence in a safe manner. I should have controlled first; and instructed after as to the reason for my actions.

Original NASA ASRS Text

Title: TRACON Controller providing OJT described a loss of separation event during attempts to vector aircraft below an overcast layer for visual approaches; the reporter acknowledging a failure to intervene in a timely manner.

Narrative: I was providing instruction on the north final to Runway 26R. We were doing visual approaches; but had to get the aircraft down and close due to clouds and visibility. The Developmental was working a situation closer to the airport with a few airplanes trying to keep them separated. The CRJ2 came over slightly high and fast; so with the cloud base at about 6;300 MSL; we had to get the aircraft down to get the airport or proceeding aircraft insight. The B717 was inbound to Runway 27L; and had not seen the airport yet and was turning into final at 7;000 FT. Timely action was not taken to put the CRJ2 into a place to do anything with him; so my Developmental was going to try and turn the aircraft toward the airport; but I instructed him to turn him to the left to pass behind the B717. Since I was providing this information; it was not done in a timely manner; and the two aircraft loss separation. Make sure that my Developmental had a plan to work the aircraft into a position and altitude that would work him into the sequence in a safe manner. I should have controlled first; and instructed after as to the reason for my actions.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	999207
Time
Date	201203
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	Regional Jet 200 ER/LR (CRJ200)
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	B717 (Formerly MD-95)
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Approach Departure
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Deviation - Procedural Published Material / Policy

TRACON controller providing OJT described a loss of separation event during attempts to vector aircraft below an overcast layer for visual approaches; the reporter acknowledging a failure to intervene in a timely manner.