Date: 201204
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: SR20
Operating under: Part 91
Flight plan: IFR
Airspace: Class D ZZZ
ATC / advisory: TRACON ZZZ
Second aircraft: PA-31T Cheyenne II
Reporter organization: Government
Reporter function: Departure; Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Confusion; Communication Breakdown
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance
Contributing factors: Human Factors; Procedure
Primary problem: Ambiguous

Narrative: The airport was on a Runway 27 operation while I was running practice ILS approaches to Runway 36. Prior to a call for release for a Piper; I requested a SR20 doing the ILS 36 and northbound on the miss. The LOA requires a heading of 270 and 2;000 FT for climb out instructions off of Runway 36. The airport unabled my northbound request so the SR20 was given 270 and 2;000 on the miss and switched to the Tower on about a 5-10 mile final. Tower called to request release on the Piper; a PAY2 going to the south requesting above 10;000 FT. At this point the SR20 was on about a 3 mile final. I said 'Reference the SR20; the Piper heading 240 and 2;000 released.' Several other LOA's with Towers in our airspace state we can use that phraseology and it is the equivalent to saying 'Visual Separation Approved.' I assumed the Tower would be using visual separation between the two aircraft. The Tower broke off the SR20's approach early which placed him south of the Runway 27 departure end. The Piper was cleared for take off and given the 240 heading which placed him in close proximity to the SR20. Separation was lost prior to the frequency change. I called traffic to the Piper; he saw the SR20 and I turned him southbound to go behind the SR20; but neglected to say 'Maintain Visual Separation' simply because I thought the Tower provided this and I was just seconds away from having divergence. I never questioned the airport if they used Visual Separation. Even though the LOA we have with the airport doesn't say that we can say 'Released Reference (Call Sign)' which means they will provide visual separation; I feel releasing an aircraft reference another IFR aircraft should hold the Tower responsible for providing some sort of separation whether it is 3 miles; 1;000 FT; divergence; or Visual Separation. We have 7 satellite airports within our airspace and 7 completely different LOA's. Missed approach instructions; scratch pad entries; departure release procedures are all different. There is no reason for the LOA's to be out dated like they are and not uniform. If there is going to be an Air Traffic Control Tower working IFR aircraft; they should be responsible for providing separation. I could have climbed the SR20 to 3;000 or the Piper on contact and would have given us a bit more room but by saying 'Released Reference (Call Sign)' not meaning that the Tower has to give me two separated aircraft is a horribly unsafe procedure.




Synopsis: TRACON Controller described a loss of separation event when coordination with a Tower regarding missed approach instructions were less than clear; the reporter indicating changes in the Tower/TRACON LOA would improve coordination and operations.