Carb icing conditions

Does anyone really use a chart for predicting carb icing??

This came up recently on the Socata TB forum. It seems there is something fundamentally different about European air and it ices up much sooner ;-)

IMO, you need to know your aeroplane and the conditions in which it might produce carb ice, and use the heater appropriately. There's no harm in putting the carb heat on in a low power descent - just make sure you take it off before short final so you have immediate power to go around...

My TB10 has a carb heat gauge - I find it an excellent indicator of possible icing conditions. Other people (possibly on other types) think they are useless.

I'll be honest, I cant picture those charts in my head, nor do I reference them before any flight. At the moment, I apply carb heat just before lining up, every 10 minutes or so, at a waypoint (just a habit from the learning days), and when doing a low power descent. Unless you have gauges or detect engine roughness, is there anything else you can do?

I know almost nothing about the TB10 but I recall reading somewhere that it is not too liable to icing because the carb inlet air is warmed a bit by the exhaust.

Carb icing is probably a big factor in unexplained engine stoppages, and the evidence is never there when you look for it. It's probably responsible for quite a few deaths.

Carb ice is normal with an O200 using mogas in Scotland. Often it will form on start-up, when there's no heat available, and the engine will stop. After a few fire-ups, the exhaust is hot enough to keep it running. I sometimes apply carb heat as I open the throttle on take-off, then go to cold air after reaching full rpm. I've had it when the charts indicate it's too cold to happen - but on a Konsin treated wet runway. Taxi-ing on wet grass is also conducive to it. Once the engine is hot, carb heat will shift it, provided it is applied early enough. I know, but never bother with, the charts - but i do notice the temp-dew point difference. The carb icing potential can vary a lot during a 1 hour flight below 3000'. I tried going to cold air on short final - but reverted to keeping hot air until after landing or full throttle for go-around, after the engine spluttered as I applied throttle to turn on the runway after landing. I was taught to push in carb heat and throttle simultaneously for a go-around. The time difference is negligable.

Unless you have gauges or detect engine roughness, is there anything else you can do?

During my IR training on a PA28, I was taught to also apply carb heat when entering clouds...

TThierry, there is a problem with the FAA diagram in your first post. It shows 100% humidity as dewpoint being 10 C above ambient temp, which of course is nonsense. So that one is NOT to believe.

Apart from that, the I donot find it too surprising that different diagrams are in circulation. After all, icing is engine/airframe specific, and the "true" risk diagram will depend on e.g. the temperature drop in the venturi.

In my local flying club the diagram is hanging on the wall and it gets consulted frequently. I think it drives home the main point well: carb ice is most likely in medium ambient temperatures, and is not just a winter phenomenon as som pilots would otherwise believe.

I like carb thermometers. They make it sensible to sometimes apply partial carb heat, and they show exactly the effectiveness of the carb heat.

During my IR training on a PA28, I was taught to also apply carb heat when entering clouds...

Thats a good point and actually I realised I do that subconsciously anyhow. The absolute last place I want to find or have to deal with carb ice is just after having entered cloud and already increased the workload.

Unless you have gauges or detect engine roughness, is there anything else you can do?

Fuel injection? :)