Cessna 340/340A
Air Traffic Control Fully Certified
Situational Awareness
ATC Issue All Types; Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Declared Emergency
Human Factors
I was training a Developmental on satellite. A C340 departed [a Class D airport] and about 18 miles south called up with a rough running engine and wanted to return; the Departure Controller declared an emergency for him. When the C340 was about 12-14 miles south of [their departure airport]; Tower called for a release of a northbound aircraft; my Trainee said hold for release. I had her call right back and release the aircraft on a 330 heading as I saw it to be no factor with the inbound emergency. The Departure Controller kept the emergency on his frequency to avoid frequency changes. The departure; a TBM8 took longer to get airborne than I anticipated. The C340 did something I did not anticipate and headed right toward the departure end of Runway 24. The C340 was already on the visual and talking to Tower when the TBM8 came off. When the TBM8 came off and started his turn to the northwest; it appeared that the C340 was less than 3 miles and 1;000 FT from the TBM8. I eventually had divergence but am not sure if I had it in time; nor did I ask the Tower if they were providing visual separation. At no time do I feel safety was compromised. It was just an unusual situation based upon pilot actions and delayed departure. I should have double checked that Tower was providing visual.
TRACON Controller described a conflict event between an inbound emergency aircraft and a departure when the departure was late in rolling; the reporter noting uncertainty regarding Tower visual separation applications.