PC-12
Air Traffic Control Fully Certified
Communication Breakdown; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Aircraft; Human Factors
I vectored a PC12 for an ILS Approach to Runway 29R. I turned the aircraft on to final approximately 4 miles outside the final approach fix at 2;000 FT and cleared him for the approach. I gave him a frequency change to Tower; and immediately after; I noticed that the aircraft was making a left turn off the final approach into higher terrain and descending to 1;700 FT. I called Tower to find out if they were talking to the aircraft; they said he hadn't called. I alerted the Supervisor to the problem; and continued to try and contact the PC12; without any success. I called Tower again to see if he had called yet; he had not. I then made a broadcast in the blind 'PC12 is dangerously low; approaching higher terrain; and should climb immediately'. The PC12 came back on frequency advising that he was climbing. At the same time I had an AS65 at 3;000 FT in the same vicinity; and another aircraft behind the AS65 at 4;000 FT. The PC12 kept climbing through 3;000 FT; and soon as I was able I turned the aircraft away from the AS65. I was not able to maintain standard separation; due to the incident; and the pilot's actions. I had the pilot of the PC12 call us after he landed; he was very thankful for my actions; and said that he had a malfunction of the auto-pilot and was banking and descending without realizing it. Have the pilot not try to fix the auto pilot while on final approach.
TRACON Controller described a loss of separation event when traffic on final for an ILS approach suddenly turned off the final in a descent and failed to respond to repeated radio calls.