Narrative:

I filed my IFR flight plan for 8000 feet. Soon after establishing cruise altitude I realized I was still IMC and requested 10;000 ft to be above cloud level. I was cleared by ATC to 10;000 ft. The controller asked for a PIREP. I reported temp -7; wind and no turbulence with buildup ahead of me. He informed me of moderate precip 20 miles ahead. I requested permission to deviate west to avoid build up. He approved deviation with instructions to inform ATC when back on course. I deviated to the west then received a vector to 300 degrees to avoid restricted airspace. I acknowledged; deviated to 300 degrees. During this time I was intermittently in and out of cloud tops for a few seconds. The new vector heading sent me into a cloud I estimate about 1/2 mile wide and 500 feet above my elevation. Upon entering the cloud I immediately began to accumulate ice on my windshield and wing struts. I had already switched on my pitot 30 min earlier but almost immediately experienced a 15 knot decrease in my airspeed. I immediately turned off my autopilot and requested to immediately increase my altitude to 12;000 feet. I had no visibility or turbulence. I had no response from ATC and decided to increase my altitude to 12;000 to avoid further icing. The rate of climb was poor; but I was able to achieve about 300 feet/minute. I called ATC again with no response of my change in altitude. About 1 min later ATC responded 'turn immediately to 360 degrees' which I immediately responded and turned. I was still in IMC; but ice accumulation was not as significant and I was still able to achieve a positive rate of climb. I again informed ATC I was in icing conditions and needed 12000 ft altitude to exit the IMC conditions. I now heard ATC advise an [air carrier] flight to immediately turn; the [air carrier] pilot stated he saw my plane on TCAS and deviated away from me. I have tis on my G1000 equipped plane and saw the [air carrier] flight at my altitude come to about 2 miles from my location before deviating. [ATC] then instructed me to contact center; I switched to their frequency and at about 11;500 ft I exited IMC on top.I was able to maintain a cruise speed about 10 knots less than my usual speed. I shed the ice 40 min later when descending. Center instructed me to phone them about my clearance deviation upon landing. The ATC supervisor listened to my account of the episode and informed me the controller was on a landline during the time I called him twice about my icing predicament and climb to get out of IMC/icing conditions. He acknowledged he understood my clearance deviation for icing. In my opinion everything worked well for this situation. If my immediate deviation did not improve my icing problem I would have declared an emergency and continued my plan of climbing out of IMC/icing conditions. The time between my deviation and actually speaking with ATC was about 45-60 seconds. Of course; at the time the duration of radio silence from ATC seemed excessive. The controller deviated me and the [air carrier] flight appropriately to avoid close contact. If he had not been on a landline I suspect he would have given me a vector to avoid the conflict entirely.

Google
 

Original NASA ASRS Text

Title: C182 pilot reported climbing from his assigned altitude to get out of icing conditions prompting an air carrier flight to deviate in response to a TCAS alert.

Narrative: I filed my IFR flight plan for 8000 feet. Soon after establishing cruise altitude I realized I was still IMC and requested 10;000 ft to be above cloud level. I was cleared by ATC to 10;000 ft. The Controller asked for a PIREP. I reported temp -7; wind and no turbulence with buildup ahead of me. He informed me of moderate precip 20 miles ahead. I requested permission to deviate west to avoid build up. He approved deviation with instructions to inform ATC when back on course. I deviated to the west then received a vector to 300 degrees to avoid restricted airspace. I acknowledged; deviated to 300 degrees. During this time I was intermittently in and out of cloud tops for a few seconds. The new vector heading sent me into a cloud I estimate about 1/2 mile wide and 500 feet above my elevation. Upon entering the cloud I immediately began to accumulate ice on my windshield and wing struts. I had already switched on my pitot 30 min earlier but almost immediately experienced a 15 knot decrease in my airspeed. I immediately turned off my autopilot and requested to immediately increase my altitude to 12;000 feet. I had no visibility or turbulence. I had no response from ATC and decided to increase my altitude to 12;000 to avoid further icing. The rate of climb was poor; but I was able to achieve about 300 feet/minute. I called ATC again with no response of my change in altitude. About 1 min later ATC responded 'turn immediately to 360 degrees' which I immediately responded and turned. I was still in IMC; but ice accumulation was not as significant and I was still able to achieve a positive rate of climb. I again informed ATC I was in icing conditions and needed 12000 ft altitude to exit the IMC conditions. I now heard ATC advise an [air carrier] flight to immediately turn; the [air carrier] pilot stated he saw my plane on TCAS and deviated away from me. I have TIS on my G1000 equipped plane and saw the [air carrier] flight at my altitude come to about 2 miles from my location before deviating. [ATC] then instructed me to contact Center; I switched to their frequency and at about 11;500 ft I exited IMC on top.I was able to maintain a cruise speed about 10 knots less than my usual speed. I shed the ice 40 min later when descending. Center instructed me to phone them about my clearance deviation upon landing. The ATC supervisor listened to my account of the episode and informed me the Controller was on a landline during the time I called him twice about my icing predicament and climb to get out of IMC/icing conditions. He acknowledged he understood my clearance deviation for icing. In my opinion everything worked well for this situation. If my immediate deviation did not improve my icing problem I would have declared an emergency and continued my plan of climbing out of IMC/icing conditions. The time between my deviation and actually speaking with ATC was about 45-60 seconds. Of course; at the time the duration of radio silence from ATC seemed excessive. The Controller deviated me and the [air carrier] flight appropriately to avoid close contact. If he had not been on a landline I suspect he would have given me a vector to avoid the conflict entirely.

Data retrieved from NASA's ASRS site 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.