Narrative:

I was on an IFR cross country flight with 1 of my instrument students from sus to cou in IMC with tops at 3500-4000 ft. After being cleared to 4000 ft, we climbed out of the clouds and stayed on top for several min. Because there was no forecast or PIREPS for icing conditions along our route, I requested descent to 3000 ft so my student could get more experience in actual. After several min in the clouds, we started accumulating rime ice on the wings and windshield. At the same time, the engine began running rough, so we immediately applied carburetor heat and were cleared back up to 4000 ft. This was my first encounter with icing conditions and I didn't know exactly what to expect, but I knew we would have to go back into the ice during our approach into cou. When we were handed off to cou approach, we were cleared for the ILS runway 2 approach. Because my student and I were both shook up over the icing situation and because his aircraft is the only one I fly without ADF equipment, I overlooked the footnote at the bottom of the approach that read 'ADF or DME required.' (this aircraft doesn't have ADF or DME.) after crossing the couvor, we descended to 2700 ft on the cou transition for the ILS and were told to report zodia outbound. As soon as we entered the clouds, we began accumulating ice, but this time at a faster rate. When we reached zodia, the marker beacon aural tone was very weak and the blue light never appeared. Because we did receive a tone, we reported zodia outbound and began the procedure turn. When we turned back inbound, we never received the marker or the localizer, so we declared a missed approach and was instructed to proceed to cou VOR. While en route to the VOR, I requested and received clearance back to spirit, our filed alternate. As we began back to spirity, the engine began to run rough, but this time it was accompanied by a slight vibration. I decided that we should land as soon as possible so I requested the VOR runway 20 into cou. We were instructed to hold over the VOR at 4000 ft. While holding on top, I noticed that the ice wasn't coming off the airframe like it had on the first encounter, and when we descended for the VOR 20 approach we accumulated even more ice. We were, however able to successfully complete the approach and land without incident. Contributing factors: no forecast for icing conditions -- had icing been in the forecast, we would never have taken the flight. After we reported icing, numerous other aircraft in the area also reported ice encounters. Forecasters should not hesitate to include icing in their forecasts. Misreading the approach chart -- both myself and my student missed the footnote at the bottom of the chart which requires the use of ADF or DME equipment (neither of which is usually required on an ILS approach). Usually, when special equipment such as DME is required, it is so stated in big bold letters at the top and bottom of the approach chart (ILS/DME or VOR/DME). Therefore, I feel that the statement (ILS/DME or ADF) or similar phraseology should be printed in big bold letters at the top and bottom of this approach chart. Airframe icing -- after subsequent flts with the aircraft in VFR conditions, I have come to the conclusion that the problems occurring with both the NAVAID reception and the rough running/vibrating engine were the direct result of the icing encounter. Ice accumulation on the antennas can disrupt NAVAID reception and ice accumulation on the airframe and propeller can cause vibrations. This can be supported by the fact that after we landed, we heard over the tower frequency a twin cessna that reported losing his DME equipment and also having trouble receiving the localizer. I included in this report a copy of the ILS runway 2 at cou along with a copy of an approach that requires DME (and so indicates in big bold letters) to help illustrate how easy it is to miss the footnote at the bottom of the ILS runway 2 requiring ADF or DME. I feel that all charts that require ADF, DME or any other equipment (such as radar) should so indicate in big bold letters at the top and bottom of the chart.

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Original NASA ASRS Text

Title: SMA ENCOUNTERS ICING ON APCH. MAKES GAR AND RETURN TO LAND.

Narrative: I WAS ON AN IFR XCOUNTRY FLT WITH 1 OF MY INST STUDENTS FROM SUS TO COU IN IMC WITH TOPS AT 3500-4000 FT. AFTER BEING CLRED TO 4000 FT, WE CLBED OUT OF THE CLOUDS AND STAYED ON TOP FOR SEVERAL MIN. BECAUSE THERE WAS NO FORECAST OR PIREPS FOR ICING CONDITIONS ALONG OUR RTE, I REQUESTED DSCNT TO 3000 FT SO MY STUDENT COULD GET MORE EXPERIENCE IN ACTUAL. AFTER SEVERAL MIN IN THE CLOUDS, WE STARTED ACCUMULATING RIME ICE ON THE WINGS AND WINDSHIELD. AT THE SAME TIME, THE ENG BEGAN RUNNING ROUGH, SO WE IMMEDIATELY APPLIED CARB HEAT AND WERE CLRED BACK UP TO 4000 FT. THIS WAS MY FIRST ENCOUNTER WITH ICING CONDITIONS AND I DIDN'T KNOW EXACTLY WHAT TO EXPECT, BUT I KNEW WE WOULD HAVE TO GO BACK INTO THE ICE DURING OUR APCH INTO COU. WHEN WE WERE HANDED OFF TO COU APCH, WE WERE CLRED FOR THE ILS RWY 2 APCH. BECAUSE MY STUDENT AND I WERE BOTH SHOOK UP OVER THE ICING SIT AND BECAUSE HIS ACFT IS THE ONLY ONE I FLY WITHOUT ADF EQUIP, I OVERLOOKED THE FOOTNOTE AT THE BOTTOM OF THE APCH THAT READ 'ADF OR DME REQUIRED.' (THIS ACFT DOESN'T HAVE ADF OR DME.) AFTER XING THE COUVOR, WE DSNDED TO 2700 FT ON THE COU TRANSITION FOR THE ILS AND WERE TOLD TO RPT ZODIA OUTBOUND. AS SOON AS WE ENTERED THE CLOUDS, WE BEGAN ACCUMULATING ICE, BUT THIS TIME AT A FASTER RATE. WHEN WE REACHED ZODIA, THE MARKER BEACON AURAL TONE WAS VERY WEAK AND THE BLUE LIGHT NEVER APPEARED. BECAUSE WE DID RECEIVE A TONE, WE RPTED ZODIA OUTBOUND AND BEGAN THE PROC TURN. WHEN WE TURNED BACK INBOUND, WE NEVER RECEIVED THE MARKER OR THE LOC, SO WE DECLARED A MISSED APCH AND WAS INSTRUCTED TO PROCEED TO COU VOR. WHILE ENRTE TO THE VOR, I REQUESTED AND RECEIVED CLRNC BACK TO SPIRIT, OUR FILED ALTERNATE. AS WE BEGAN BACK TO SPIRITY, THE ENG BEGAN TO RUN ROUGH, BUT THIS TIME IT WAS ACCOMPANIED BY A SLIGHT VIBRATION. I DECIDED THAT WE SHOULD LAND AS SOON AS POSSIBLE SO I REQUESTED THE VOR RWY 20 INTO COU. WE WERE INSTRUCTED TO HOLD OVER THE VOR AT 4000 FT. WHILE HOLDING ON TOP, I NOTICED THAT THE ICE WASN'T COMING OFF THE AIRFRAME LIKE IT HAD ON THE FIRST ENCOUNTER, AND WHEN WE DSNDED FOR THE VOR 20 APCH WE ACCUMULATED EVEN MORE ICE. WE WERE, HOWEVER ABLE TO SUCCESSFULLY COMPLETE THE APCH AND LAND WITHOUT INCIDENT. CONTRIBUTING FACTORS: NO FORECAST FOR ICING CONDITIONS -- HAD ICING BEEN IN THE FORECAST, WE WOULD NEVER HAVE TAKEN THE FLT. AFTER WE RPTED ICING, NUMEROUS OTHER ACFT IN THE AREA ALSO RPTED ICE ENCOUNTERS. FORECASTERS SHOULD NOT HESITATE TO INCLUDE ICING IN THEIR FORECASTS. MISREADING THE APCH CHART -- BOTH MYSELF AND MY STUDENT MISSED THE FOOTNOTE AT THE BOTTOM OF THE CHART WHICH REQUIRES THE USE OF ADF OR DME EQUIP (NEITHER OF WHICH IS USUALLY REQUIRED ON AN ILS APCH). USUALLY, WHEN SPECIAL EQUIP SUCH AS DME IS REQUIRED, IT IS SO STATED IN BIG BOLD LETTERS AT THE TOP AND BOTTOM OF THE APCH CHART (ILS/DME OR VOR/DME). THEREFORE, I FEEL THAT THE STATEMENT (ILS/DME OR ADF) OR SIMILAR PHRASEOLOGY SHOULD BE PRINTED IN BIG BOLD LETTERS AT THE TOP AND BOTTOM OF THIS APCH CHART. AIRFRAME ICING -- AFTER SUBSEQUENT FLTS WITH THE ACFT IN VFR CONDITIONS, I HAVE COME TO THE CONCLUSION THAT THE PROBS OCCURRING WITH BOTH THE NAVAID RECEPTION AND THE ROUGH RUNNING/VIBRATING ENG WERE THE DIRECT RESULT OF THE ICING ENCOUNTER. ICE ACCUMULATION ON THE ANTENNAS CAN DISRUPT NAVAID RECEPTION AND ICE ACCUMULATION ON THE AIRFRAME AND PROP CAN CAUSE VIBRATIONS. THIS CAN BE SUPPORTED BY THE FACT THAT AFTER WE LANDED, WE HEARD OVER THE TWR FREQ A TWIN CESSNA THAT RPTED LOSING HIS DME EQUIP AND ALSO HAVING TROUBLE RECEIVING THE LOC. I INCLUDED IN THIS RPT A COPY OF THE ILS RWY 2 AT COU ALONG WITH A COPY OF AN APCH THAT REQUIRES DME (AND SO INDICATES IN BIG BOLD LETTERS) TO HELP ILLUSTRATE HOW EASY IT IS TO MISS THE FOOTNOTE AT THE BOTTOM OF THE ILS RWY 2 REQUIRING ADF OR DME. I FEEL THAT ALL CHARTS THAT REQUIRE ADF, DME OR ANY OTHER EQUIP (SUCH AS RADAR) SHOULD SO INDICATE IN BIG BOLD LETTERS AT THE TOP AND BOTTOM OF THE CHART.

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.