Aircraft equipment problem creates need for flight assist.

Attributes
ACN	264637
Time
Date	199402
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : amn airport : lan
State Reference	MI
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : lan
Operator	general aviation : personal
Make Model Name	Cessna 150
Operating Under FAR Part	Part 91
Flight Phase	cruise other other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private pilot : commercial
Experience	flight time last 90 days : 50 flight time total : 510 flight time type : 150
ASRS Report	264637
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather
Independent Detector	other flight crewa
Resolutory Action	controller : provided flight assist flight crew : overcame equipment problem flight crew : declared emergency
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

I departed cad in good VFR WX. I was flying to the mop VOR and then south to lan. Upon passing to the west of mop I could see snow showers in the distance. I had received a WX brief so I knew they existed and thought I may arrive at the same time. Approximately 10 mi south of alma, mi, I began to experience serious engine roughness. Enough for me to seek radar vectors to the nearest airport from lan approach. They gave me vectors for alma while I was in MVFR and was adjusting mixture, throttle, and carburetor heat in an attempt to keep the engine running. I managed to reach 2300 RPM in the ce-150 and advised lan approach that I could make lan. So, they gave me vectors for the lan ILS runway 10R final approach course. At approximately 15 mi north of the ionia airport, I experienced engine roughness again, somewhat more violent. I was now in IMC with snow. I once again asked for vectors to the nearest airport. They gave me vectors for ionia and I began to head for it. I managed to adjust the engine controls enough to hold altitude and 2000 RPM. I called lan approach again and told them I felt I could make lan. They gave me vectors for the lan ILS runway 10R approach, and I informed them that we probably only had 1 chance to make the approach and I only would be capable of shooting the localizer approach. I told them that I would like to keep the approach in tight and that I would like a radar/surveillance approach. They said that would be no problem. The lan approach/tower staff was, as usual, great and cooperative. I flew the surveillance approach and spotted the approach lights and was cleared to land on 10R at lan. I landed with the engine seeming to run well at normal power and idle. The tower never asked me to contact them, but I know the tower staff and I went and spoke with them. They said that I did a nice job and that nothing went wrong as far as the textbook is concerned. I feel that I had a serious encounter with carburetor ice, or my magnetos or plugs were seriously malfunctioning/not performing up to standards. I am having new mags put on and the spark plugs and wires inspected. The exhaust and carburetor are also being completely inspected.

Original NASA ASRS Text

Title: ACFT EQUIP PROB CREATES NEED FOR FLT ASSIST.

Narrative: I DEPARTED CAD IN GOOD VFR WX. I WAS FLYING TO THE MOP VOR AND THEN S TO LAN. UPON PASSING TO THE W OF MOP I COULD SEE SNOW SHOWERS IN THE DISTANCE. I HAD RECEIVED A WX BRIEF SO I KNEW THEY EXISTED AND THOUGHT I MAY ARRIVE AT THE SAME TIME. APPROX 10 MI S OF ALMA, MI, I BEGAN TO EXPERIENCE SERIOUS ENG ROUGHNESS. ENOUGH FOR ME TO SEEK RADAR VECTORS TO THE NEAREST ARPT FROM LAN APCH. THEY GAVE ME VECTORS FOR ALMA WHILE I WAS IN MVFR AND WAS ADJUSTING MIXTURE, THROTTLE, AND CARB HEAT IN AN ATTEMPT TO KEEP THE ENG RUNNING. I MANAGED TO REACH 2300 RPM IN THE CE-150 AND ADVISED LAN APCH THAT I COULD MAKE LAN. SO, THEY GAVE ME VECTORS FOR THE LAN ILS RWY 10R FINAL APCH COURSE. AT APPROX 15 MI N OF THE IONIA ARPT, I EXPERIENCED ENG ROUGHNESS AGAIN, SOMEWHAT MORE VIOLENT. I WAS NOW IN IMC WITH SNOW. I ONCE AGAIN ASKED FOR VECTORS TO THE NEAREST ARPT. THEY GAVE ME VECTORS FOR IONIA AND I BEGAN TO HEAD FOR IT. I MANAGED TO ADJUST THE ENG CTLS ENOUGH TO HOLD ALT AND 2000 RPM. I CALLED LAN APCH AGAIN AND TOLD THEM I FELT I COULD MAKE LAN. THEY GAVE ME VECTORS FOR THE LAN ILS RWY 10R APCH, AND I INFORMED THEM THAT WE PROBABLY ONLY HAD 1 CHANCE TO MAKE THE APCH AND I ONLY WOULD BE CAPABLE OF SHOOTING THE LOC APCH. I TOLD THEM THAT I WOULD LIKE TO KEEP THE APCH IN TIGHT AND THAT I WOULD LIKE A RADAR/SURVEILLANCE APCH. THEY SAID THAT WOULD BE NO PROB. THE LAN APCH/TWR STAFF WAS, AS USUAL, GREAT AND COOPERATIVE. I FLEW THE SURVEILLANCE APCH AND SPOTTED THE APCH LIGHTS AND WAS CLRED TO LAND ON 10R AT LAN. I LANDED WITH THE ENG SEEMING TO RUN WELL AT NORMAL PWR AND IDLE. THE TWR NEVER ASKED ME TO CONTACT THEM, BUT I KNOW THE TWR STAFF AND I WENT AND SPOKE WITH THEM. THEY SAID THAT I DID A NICE JOB AND THAT NOTHING WENT WRONG AS FAR AS THE TEXTBOOK IS CONCERNED. I FEEL THAT I HAD A SERIOUS ENCOUNTER WITH CARB ICE, OR MY MAGNETOS OR PLUGS WERE SERIOUSLY MALFUNCTIONING/NOT PERFORMING UP TO STANDARDS. I AM HAVING NEW MAGS PUT ON AND THE SPARK PLUGS AND WIRES INSPECTED. THE EXHAUST AND CARB ARE ALSO BEING COMPLETELY INSPECTED.

Data retrieved from NASA's ASRS site as of July 2007 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.