Forced landing caused by carburetor icing.

Attributes
ACN	284504
Time
Date	199409
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : 2g9
State Reference	PA
Altitude	msl bound lower : 6500 msl bound upper : 6500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	general aviation : instructional
Make Model Name	Cessna 150
Operating Under FAR Part	Part 91
Flight Phase	cruise other other other
Route In Use	enroute : on vectors
Flight Plan	VFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 40 flight time total : 300 flight time type : 35
ASRS Report	284504
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	controller : provided flight assist flight crew : declared emergency none taken : unable other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I took off solo from I62 to 79N on sat/xx/94 in a cessna 150M. The aircraft was tied down at open field with tanks half full. In the morning of the incident I delayed my departure because of heavy frost on aircraft. After it was melted, I refueled and took off at XX30 EST. There was no visible moisture. I climbed to 4500 ft, leveled and leaned the mixture. Then around XY30 I climbed to 6500 ft at just short of full power and the mixture left at the previous position. Leveled off at 6500 ft with enough terrain clearance. Then I tried to adjust the mixture. As soon as I pushed the mixture full rich to see RPM change, engine became rough. Immediately throttle was set to full power, but it did not help. The RPM gradually worsened with fluctuation. At 1500 RPM I began descent. The throttle was at full power position and the mixture at full rich until touchdown. As the radio was set to maximum gross weight ct, I called it but had no response. I then called on 121.5 that due to rough engine I am attempting an off-field landing. It was 4000 ft AGL so the transponder was left at 1200. After 3 calls on 121.5, an airline above responded and recommended ZDC, which handed me to ZOB. ZOB requested me to squawk 7700 and gave me radar vector to 2g9. The problem was discussed with FBO at 2g9 and at I62. We concluded it was not water in the tank but carburetor icing. I did a careful preflight check and thereafter had no engine roughness until landing at I62. I think it's better to have center frequencys in the ct frequency list in the sectional. Callback conversation with reporter revealed the following information: pilot was called to verify if he had used any carburetor heat during the time of engine roughness. He had not used any heat as the skies had no visible moisture. In his mind he could not have carburetor ice. Although he had waited for ice to melt (or frost) from his aircraft before departing, it might have been a clue for a more experienced pilot.

Original NASA ASRS Text

Title: FORCED LNDG CAUSED BY CARB ICING.

Narrative: I TOOK OFF SOLO FROM I62 TO 79N ON SAT/XX/94 IN A CESSNA 150M. THE ACFT WAS TIED DOWN AT OPEN FIELD WITH TANKS HALF FULL. IN THE MORNING OF THE INCIDENT I DELAYED MY DEP BECAUSE OF HVY FROST ON ACFT. AFTER IT WAS MELTED, I REFUELED AND TOOK OFF AT XX30 EST. THERE WAS NO VISIBLE MOISTURE. I CLBED TO 4500 FT, LEVELED AND LEANED THE MIXTURE. THEN AROUND XY30 I CLBED TO 6500 FT AT JUST SHORT OF FULL PWR AND THE MIXTURE L AT THE PREVIOUS POS. LEVELED OFF AT 6500 FT WITH ENOUGH TERRAIN CLRNC. THEN I TRIED TO ADJUST THE MIXTURE. AS SOON AS I PUSHED THE MIXTURE FULL RICH TO SEE RPM CHANGE, ENG BECAME ROUGH. IMMEDIATELY THROTTLE WAS SET TO FULL PWR, BUT IT DID NOT HELP. THE RPM GRADUALLY WORSENED WITH FLUCTUATION. AT 1500 RPM I BEGAN DSCNT. THE THROTTLE WAS AT FULL PWR POS AND THE MIXTURE AT FULL RICH UNTIL TOUCHDOWN. AS THE RADIO WAS SET TO MAX GROSS WT CT, I CALLED IT BUT HAD NO RESPONSE. I THEN CALLED ON 121.5 THAT DUE TO ROUGH ENG I AM ATTEMPTING AN OFF-FIELD LNDG. IT WAS 4000 FT AGL SO THE XPONDER WAS LEFT AT 1200. AFTER 3 CALLS ON 121.5, AN AIRLINE ABOVE RESPONDED AND RECOMMENDED ZDC, WHICH HANDED ME TO ZOB. ZOB REQUESTED ME TO SQUAWK 7700 AND GAVE ME RADAR VECTOR TO 2G9. THE PROB WAS DISCUSSED WITH FBO AT 2G9 AND AT I62. WE CONCLUDED IT WAS NOT WATER IN THE TANK BUT CARB ICING. I DID A CAREFUL PREFLT CHK AND THEREAFTER HAD NO ENG ROUGHNESS UNTIL LNDG AT I62. I THINK IT'S BETTER TO HAVE CTR FREQS IN THE CT FREQ LIST IN THE SECTIONAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: PLT WAS CALLED TO VERIFY IF HE HAD USED ANY CARB HEAT DURING THE TIME OF ENG ROUGHNESS. HE HAD NOT USED ANY HEAT AS THE SKIES HAD NO VISIBLE MOISTURE. IN HIS MIND HE COULD NOT HAVE CARB ICE. ALTHOUGH HE HAD WAITED FOR ICE TO MELT (OR FROST) FROM HIS ACFT BEFORE DEPARTING, IT MIGHT HAVE BEEN A CLUE FOR A MORE EXPERIENCED PLT.

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.