Narrative:

Oak WX XA45Z east 2500 ft overcast, 7 mi rain showers, temperature 56 degrees, dew point 56 degrees, wind 140 degrees, 13 KTS, altimeter 29.99 ft. Depart time at oak was at XB42 local. WX at takeoff was very light rain, temperature 60 degrees, light south winds, runway 11 in use, nothing to indicate a need for engine anti-ice. Takeoff and climb were normal. At approximately 2000 ft, we noticed sleet on the windshield and blades, however ram air temperature was reading plus 13 degrees C with ram air temperature meter indicating normal. Engines and indications were always normal and no problems ever encountered, however engine anti-ice and airfoil were used as a precaution. Here is a case where sleet/ice can be present at a higher ram air temperature, with possibly a low altitude temperature inversion/front along with a slow to react or sticking RAT/thrust rating indicator. A visual of ice has higher priority over ram air temperature and WX brief. Food for thought: can we be damaging or at the least decreasing the life of our engines by not using anti-ice more often in similar sits? Maybe the use of anti-ice with ram air temperature 6 or less with moisture is not conservative enough? Do our procedures need changing as far as ram air temperature is concerned, or ram air temperature 6 degrees, fronts, temperature inversion, etc. Many MD80 crewmembers, myself included, have experienced an engine that seemed to be lagging/slower to respond, whereby the use of momentary engine anti-ice has corrected the problem. Unseen, unexpected ice? Callback conversation with reporter revealed the following information: the reporter has heard nothing from his air carrier except an acknowledgement of his report. The 'RAT' that he refers to is ram air temperature, and 'tri' is thrust rating indicator.

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Original NASA ASRS Text

Title: AN ACR MD80 CAPT GOT ENG AND AIRFRAME ICING AT PLUS 13 DEG C.

Narrative: OAK WX XA45Z E 2500 FT OVCST, 7 MI RAIN SHOWERS, TEMP 56 DEGS, DEW POINT 56 DEGS, WIND 140 DEGS, 13 KTS, ALTIMETER 29.99 FT. DEPART TIME AT OAK WAS AT XB42 LCL. WX AT TKOF WAS VERY LIGHT RAIN, TEMP 60 DEGS, LIGHT S WINDS, RWY 11 IN USE, NOTHING TO INDICATE A NEED FOR ENG ANTI-ICE. TKOF AND CLB WERE NORMAL. AT APPROX 2000 FT, WE NOTICED SLEET ON THE WINDSHIELD AND BLADES, HOWEVER RAM AIR TEMP WAS READING PLUS 13 DEGS C WITH RAM AIR TEMP METER INDICATING NORMAL. ENGS AND INDICATIONS WERE ALWAYS NORMAL AND NO PROBS EVER ENCOUNTERED, HOWEVER ENG ANTI-ICE AND AIRFOIL WERE USED AS A PRECAUTION. HERE IS A CASE WHERE SLEET/ICE CAN BE PRESENT AT A HIGHER RAM AIR TEMP, WITH POSSIBLY A LOW ALT TEMP INVERSION/FRONT ALONG WITH A SLOW TO REACT OR STICKING RAT/THRUST RATING INDICATOR. A VISUAL OF ICE HAS HIGHER PRIORITY OVER RAM AIR TEMP AND WX BRIEF. FOOD FOR THOUGHT: CAN WE BE DAMAGING OR AT THE LEAST DECREASING THE LIFE OF OUR ENGS BY NOT USING ANTI-ICE MORE OFTEN IN SIMILAR SITS? MAYBE THE USE OF ANTI-ICE WITH RAM AIR TEMP 6 OR LESS WITH MOISTURE IS NOT CONSERVATIVE ENOUGH? DO OUR PROCS NEED CHANGING AS FAR AS RAM AIR TEMP IS CONCERNED, OR RAM AIR TEMP 6 DEGS, FRONTS, TEMP INVERSION, ETC. MANY MD80 CREWMEMBERS, MYSELF INCLUDED, HAVE EXPERIENCED AN ENG THAT SEEMED TO BE LAGGING/SLOWER TO RESPOND, WHEREBY THE USE OF MOMENTARY ENG ANTI-ICE HAS CORRECTED THE PROB. UNSEEN, UNEXPECTED ICE? CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR HAS HEARD NOTHING FROM HIS ACR EXCEPT AN ACKNOWLEDGEMENT OF HIS RPT. THE 'RAT' THAT HE REFERS TO IS RAM AIR TEMP, AND 'TRI' IS THRUST RATING INDICATOR.

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.