Air Traffic Control Fully Certified
Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
General Declared Emergency
Human Factors; Weather
A C172 was handed off from Center. The Controller requested 6;500 FT MSL because the pilot reported icing. On initial contact; I asked the pilot if he was still receiving ice and he said he was. I attempted to vector the aircraft on the most expeditious route to lower MVA's. When the aircraft was in the 4;500 FT MVA; he said he was continuing to accumulate ice; estimated to be 3/8 inch by now. The pilot said he was having trouble holding altitude and airspeed. I decided to declare an emergency situation without advising the pilot of this fact. Working closely with the EOVM; I descended the aircraft to the 3;500 FT MVA a couple miles prior to that MVA boundary; hoping that the icing would abate. It did not. At this point; I decided to attempt vectors to a visual approach; however; when the aircraft was one mile southwest of the airport; he was still in IMC and still accumulating ice. While the pilot remained relatively calm; I sensed he was becoming more concerned about the icing; his deteriorating airspeed; and his inability to hold assigned altitude. I asked if he had pitot and carb heat. He said he did and they were both on. I vectored the aircraft about 1/2 mile from the outer marker; assigning 2;800 FT; the glide slope intercept altitude. I cleared the C172 for the ILS approach; and he started to turn inbound. I received a landing clearance from the Tower and cleared the aircraft to land; instructing him to remain on my frequency. He seemed to follow the approach for about two miles; then appeared to stray to the east of the final. The pilot asked if he was on course and I told him he was straying eastward. The aircraft was now on about a three mile final; and I decided to give him an emergency ASR approach; assigning vectors and step-down altitudes to 1;800 FT. When the aircraft was on short final at 1;800 FT; he said he had just broken out of IMC and had the runway in sight. The pilot landed safely; and I instructed him to change to Ground Control. I was later informed ground personnel reported the aircraft had approximately 1 inch ice on all surfaces. Continue to attempt to educate the aviation community about the dangers of icing; especially to light aircraft with no icing protection.
Considering wind aloft and temperature information; mistakenly thought temps were low enough to avoid ice accumulation. About halfway into the flight noticed the beginning of some icing. Initially asked to climb higher; due to lack of performance decided on lower to 6;500 FT. Kept ATC informed on ice accumulation as various vectors and altitudes were tried to get out of the icing conditions. Ice continued to accumulate as we approached the destination. Reported up to one inch ice accumulation but may have over estimated. Ended up needing vectors to a final approach course and tension and workload increased within 3 miles of destination. Nerves made it difficult to objectively evaluate aircraft performance but it seemed to be decreasing; requiring full throttle to maintain airspeed and altitude for the last 30 miles. Poor education about icing conditions and a lack of experience led to this situation. Inaccurate assumptions almost led to an accident.
TRACON Controller described an icing event; declaring an emergency for the aircraft and providing an emergency type ASR approach to accomplish uneventful descent below IMC.