Narrative:

The aircraft was en route westbound until I noticed he was 300 ft low and I questioned him. The pilot informed me the aircraft was experiencing an engine vibration and oil pressure problem. The pilot declared an emergency and was 20-25 miles northwest of [a nearby airport] and decided to land there. The aircraft was at 10;000 ft and I issued a clearance direct [to the airport] and pilot discretion descent to 4;000 (the airplane was spiraling down to make sure he was over the airport and didn't want to lose altitude). In the meantime there was a C177/g tracking northeast bound direct and landing [another nearby airport]. A BE35 got within 3 miles of the cardinal but safety was not compromised because the pilot knew where the traffic was at all times due to traffic calls. To my knowledge the separation was 3 miles and 700 ft. I knew the airplanes would not hit each other; and I did not want to issue a clearance that would disturb or fluster the emergency aircraft. The pilot advised that he had the field in sight and wanted to cancel but I suggested that he at least keep VFR flight following until I lost him on radar. I told him to give me a call once he landed so I would know if he was ok. The pilot called me approximately 4 minutes after my last transmission and advised me he was on the ground safely. In retrospect; I should have turned the cardinal 20 to 30 degrees right and the airplanes would have been 5 miles or greater but I wanted to get the emergency aircraft down as quickly as possible. I knew the airplanes would not get together and I made a judgment call. The pilot landed with no problems and no injuries.

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Original NASA ASRS Text

Title: Enroute Controller described a less than authorized separation event when a emergency aircraft elected to circle the airport of intended landing to ensure a safe landing.

Narrative: The aircraft was en route westbound until I noticed he was 300 FT low and I questioned him. The pilot informed me the aircraft was experiencing an engine vibration and oil pressure problem. The pilot declared an emergency and was 20-25 miles northwest of [a nearby airport] and decided to land there. The aircraft was at 10;000 FT and I issued a clearance direct [to the airport] and pilot discretion descent to 4;000 (the airplane was spiraling down to make sure he was over the airport and didn't want to lose altitude). In the meantime there was a C177/g tracking northeast bound direct and landing [another nearby airport]. A BE35 got within 3 miles of the Cardinal but safety was not compromised because the pilot knew where the traffic was at all times due to traffic calls. To my knowledge the separation was 3 miles and 700 FT. I knew the airplanes would not hit each other; and I did not want to issue a clearance that would disturb or fluster the emergency aircraft. The pilot advised that he had the field in sight and wanted to cancel but I suggested that he at least keep VFR flight following until I lost him on RADAR. I told him to give me a call once he landed so I would know if he was OK. The pilot called me approximately 4 minutes after my last transmission and advised me he was on the ground safely. In retrospect; I should have turned the Cardinal 20 to 30 degrees right and the airplanes would have been 5 miles or greater but I wanted to get the emergency aircraft down as quickly as possible. I knew the airplanes would not get together and I made a judgment call. The pilot landed with no problems and no injuries.

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.