Light Transport; Low Wing; 2 Turboprop Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3.5
Communication Breakdown; Confusion; Troubleshooting; Situational Awareness; Distraction; Workload
Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; General Declared Emergency
Aircraft; Human Factors; Procedure
Aircraft X was about 15 miles east of ZZZ at 9000 feet when I observed that I was no longer receiving the Mode C altitude.  I asked the pilot to say altitude and he responded for me to stand-by.   About 2 minutes later the pilot turned about 30 degrees left of course and had still not gotten back to me on their altitude.  I asked the pilot if everything was OK and he responded no and that he wanted to divert to ZZZ.  I issued the pilot a heading towards ZZZ and asked for their current altitude.   The pilot then responded that they were at 9000 and had lost an engine and some instruments and declaring an emergency.  I gave the pilot a descent to 2000 and advised them of weather at ZZZ; asked what runway they would like and advised them of runway lengths.  The pilot said he wanted runway XX.  The tower was notified and I obtained a landing clearance for the pilot.  The pilot was cleared for the visual approach and cleared to land by me.  Aircraft X landed safely.  I realized after Aircraft X was on the ground that I never cleared them to ZZZ.  From the time the pilot told me that there was a problem to the time the pilot landed was only about 3 minutes.  I will make it a part of my mental checklist to amend the clearance in cases of emergencies.
Controller reports of an aircraft that loses an engine; declares an emergency; and then lands at a new destination.  Controller was concerned because he didn't give the aircraft a clearance to the new destination.