Thread: flying in over 90% humidity at arround 0 C

Its the first time i fly in the winter since i got my licence in september this year,so i wanted to see how is it.Since the weather is very bad,for about 6 weeks we can not fly here do to freezing fog,when i got an window of a couple of hours with a bit of sun i did it.Now i know that is not indicated to fly in those conditions but i wanted to se how my CTSW will react. The maneuvering of the plane was very slow and i had the feeling that the plane was very heavy,i was flying alone with about 15 gallons of gas.
Few days earlier with temperature 15 C under i flew and i had the best flight in my life,then the humidity % was about 40%.
Could someone try to explain me why the plane reacted so different ?

Density altitude is defined as the altitude at which a given air density is found in the standard atmosphere. For a given altitude, density altitude changes with changes in pressure, air temperature, and humidity. An increase in pressure increases air density, so it decreases density altitude. An increase in temperature decreases air density, so it increases density altitude. An increase in humidity decreases air density, so itincreases density altitude. Changes in pressure and temperature have the greatest effect on density altitude, and changes in humidity have the least effect.

here is a density altitude calculator that considers humidity http://wahiduddin.net/calc/calc_da_rh.htm play with it and you can see that the effect is minor.

if you haven't flow much lately maybe it was only perception.

yes it could have been my perceptien cause i only flew one hour in 6 weeks and there was also little bit of wind.there was definitely no ice on the wings although the conditions ware favorable for that,any way i did not feel confortable

yes could be

Gica, was your RPM lower than normal and dropping? It could be carb ice. Next time you fly in similar conditions, observe the RPM and try to pull the carb heat knob. See if the RPM (and aircraft performance) improves as a result.

On a recent flight from Cincinnati to Danbury I had conditions similar to the ones you describe at one point during the flight. I noticed the climb performance and airspeed descrease, and then I noticed the RPM drop below 5000 (I was at WOT and I generally get about 5300 RPM). I pulled on the carb heat knob and the RPM built back up slowly, as did the performance.

I am told that Rotax is not generally susceptible to carb icing, and the carb heat on the CT is only an alternate air source beneath the cowling. But carb ice does happen sometimes and having warmer air on the intake appears to alleviate the problem.

hallo Hedger

I know that carb ice is the big danger when i fly in those whether conditions thats why to prevent it i flew with the carb heat pulled like 20 % all the time exepting by take off and still i had that felling very strong.Have you ever flew in 40 degrees centigrees heat with booth tanks full and two heavy people in the plane? The plane would react very slow to each stick command, exactly the same feeling i had now,i can not understand why do you?