TazzyTazzy
Pre-takeoff checklist
- Joined
- Sep 17, 2013
- Messages
- 359
- Display Name
Display name:
Mitch
Happy new year everyone. I have a carb icing and safety of flight question in a 172N. I want to do this flight tonight, and based on weather from last night, tonight's weather should be about the same. As a newbie (100 hrs), I haven't flown in weather this cold yet. So, lets say I want to do a night VFR flight.
Assume that I take off in 45f degree weather at around sunset, with a dew point at 41 (86% relative humidity). Then, by the time I land or do some stop & go to keep night currency after my flight the metar is showing:
KABC 050555Z AUTO 02003KT 10SM CLR 02/00 A3044 RMK AO1
This puts the relative humidity at 91% with no forecast fog and typically doesn't get fog - I'd like to avoid visibility debate for this. Last night was clear in these conditions and forecast to be the same and clear tonight.
Looking up charts and such, it seems I'm getting into the severe carb icing range. Would this be considered an unsafe flight?
What procedures should I do that I wouldn't do otherwise in conditions not expected for carb ice. Do I use carb heat all the time? What about take off and forming carb ice on take off/climb out? Using carb heat will affect the performance of the engine, but it's pretty cold air and might still be colder than air on a hot 105f degree day (I guess).
On run-up, I pull carb heat and note the RPM drop. I'll still do that, but what if the engine chokes and cleans up after (I know that's a sign of melted ice that engine is sucking down), but then do I keep the carb heat on if there was ice? Do I leave it on until roll out?
I live in the Sacramento, it's not supposed to be this cold darn it. I never trained in these conditions, just covered some in flight school, but not experienced these temps while I trained so I didn't think about these details.
What other factors do I need to consider, other than a couple of blankets and hand warmers and such if needed in an emergency. I know I'll need to check for frost.
Thanks.
Assume that I take off in 45f degree weather at around sunset, with a dew point at 41 (86% relative humidity). Then, by the time I land or do some stop & go to keep night currency after my flight the metar is showing:
KABC 050555Z AUTO 02003KT 10SM CLR 02/00 A3044 RMK AO1
This puts the relative humidity at 91% with no forecast fog and typically doesn't get fog - I'd like to avoid visibility debate for this. Last night was clear in these conditions and forecast to be the same and clear tonight.
Looking up charts and such, it seems I'm getting into the severe carb icing range. Would this be considered an unsafe flight?
What procedures should I do that I wouldn't do otherwise in conditions not expected for carb ice. Do I use carb heat all the time? What about take off and forming carb ice on take off/climb out? Using carb heat will affect the performance of the engine, but it's pretty cold air and might still be colder than air on a hot 105f degree day (I guess).
On run-up, I pull carb heat and note the RPM drop. I'll still do that, but what if the engine chokes and cleans up after (I know that's a sign of melted ice that engine is sucking down), but then do I keep the carb heat on if there was ice? Do I leave it on until roll out?
I live in the Sacramento, it's not supposed to be this cold darn it. I never trained in these conditions, just covered some in flight school, but not experienced these temps while I trained so I didn't think about these details.
What other factors do I need to consider, other than a couple of blankets and hand warmers and such if needed in an emergency. I know I'll need to check for frost.
Thanks.